Bert Bakker - Academia.edu (original) (raw)
Papers by Bert Bakker
Brain, 2014
Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorder... more Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorders, such as Alzheimer's disease, frontotemporal dementia and Parkinson's disease, and is also characteristic of neuronal intermediate filament inclusion disease. Intermediate filaments type IV include three neurofilament proteins (light, medium and heavy molecular weight neurofilament subunits) and α-internexin. The phosphorylation of intermediate filament proteins contributes to axonal growth, and is regulated by protein kinase A. Here we describe a family with a novel late-onset neurodegenerative disorder presenting with dementia and/or parkinsonism in 12 affected individuals. The disorder is characterized by a unique neuropathological phenotype displaying abundant neuronal inclusions by haematoxylin and eosin staining throughout the brain with immunoreactivity for intermediate filaments. Combining linkage analysis, exome sequencing and proteomics analysis, we identified a heterozygous c.149T>G (p.Leu50Arg) missense mutation in the gene encoding the protein kinase A type I-beta regulatory subunit (PRKAR1B). The pathogenicity of the mutation is supported by segregation in the family, absence in variant databases, and the specific accumulation of PRKAR1B in the inclusions in our cases associated with a specific biochemical pattern of PRKAR1B. Screening of PRKAR1B in 138 patients with Parkinson's disease and 56 patients with frontotemporal dementia did not identify additional novel pathogenic mutations. Our findings link a pathogenic PRKAR1B mutation to a novel hereditary neurodegenerative disorder and suggest an altered protein kinase A function through a reduced binding of the regulatory subunit to the A-kinase anchoring protein and the catalytic subunit of protein kinase A, which might result in subcellular dislocalization of the catalytic subunit and hyperphosphorylation of intermediate filaments.
Journal of the Neurological Sciences, 2009
The American Journal of Human Genetics, 1999
Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the her... more Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the hereditary multiple exostoses syndrome (EXT). Approximately 15% of all chondrosarcomas arise within the cartilaginous cap of an osteochondroma. EXT is genetically heterogeneous, and two genes, EXT1 and EXT2, located on 8q24 and 11p11-p12, respectively, have been cloned. It is still unclear whether osteochondroma is a developmental disorder or a true neoplasm. Furthermore, it is unclear whether inactivation of both alleles of an EXT gene, according to the tumor-suppressor model, is required for osteochondroma development, or whether a single EXT germline mutation acts in a dominant negative way. We therefore studied loss of heterozygosity and DNA ploidy in eight sporadic and six hereditary osteochondromas. EXT1-and EXT2-mutation analysis was performed in a total of 34 sporadic and hereditary osteochondromas and secondary peripheral chondrosarcomas. We demonstrated osteochondroma to be a true neoplasm, since aneuploidy was found in 4 of 10 osteochondromas. Furthermore, LOH was almost exclusively found at the EXT1 locus in 5 of 14 osteochondromas. Four novel constitutional cDNA alterations were detected in exon 1 of EXT1. Two patients with multiple osteochondromas demonstrated a germline mutation combined with loss of the remaining wild-type allele in three osteochondromas, indicating that, in cartilaginous cells of the growth plate, inactivation of both copies of the EXT1 gene is required for osteochondroma formation in hereditary cases. In contrast, no somatic EXT1 cDNA alterations were found in sporadic osteochondromas. No mutations were found in the EXT2 gene.
Research in Immunology, 1998
The POU homeodomain containing transcriptional activator POU1F1, formerly called Pit1 or GHF-1, i... more The POU homeodomain containing transcriptional activator POU1F1, formerly called Pit1 or GHF-1, is required for the embry- ological determination and postnatal secretory function of the GH-, PRL-, and TSH-producing cells in the anterior pituitary. Several mutations in the gene encoding POU1F1 have been described, re- sulting in a syndrome of combined pituitary hormone deficiency in- volving these three hormones. Most
Human Mutation, 2015
Facioscapulohumeral muscular dystrophy (FSHD) is most often associated with variegated expression... more Facioscapulohumeral muscular dystrophy (FSHD) is most often associated with variegated expression in somatic cells of the normally repressed DUX4 gene within the D4Z4 repeat array. The most common form, FSHD1, is caused by a D4Z4 repeat array contraction to a size of 1-10 units (normal range 10-100 units). The less common form, FSHD2, is characterized by D4Z4 CpG hypomethylation and is most often caused by loss of function mutations in the structural maintenance of chromosomes hinge domain 1 (SMCHD1) gene on chromosome 18p. The chromatin modifier SMCHD1 is necessary to maintain a repressed D4Z4 chromatin state. Here we describe two FSHD2 families with a 1.2 Mb deletion encompassing the SMCHD1 gene. Numerical aberrations of chromosome 18 are relatively common and the majority of 18p deletion syndrome (18p-) cases have, like these FSHD2 families, only one copy of SMCHD1. Our finding therefore raises the possibility that 18p- cases are at risk of developing FSHD. To address this possibility, we combined genome wide array analysis data with D4Z4 CpG methylation and repeat array sizes in individuals with 18p- and conclude that approximately 1:8 18p- cases might be at risk of developing FSHD. This article is protected by copyright. All rights reserved.
Cancer research, Jan 15, 2000
TP53 has been implicated in regulation of the cell cycle, DNA repair, and apoptosis. We studied, ... more TP53 has been implicated in regulation of the cell cycle, DNA repair, and apoptosis. We studied, in primary breast tumors through direct cDNA sequencing of exons 2-11, whether TP53 gene mutations can predict response in patients with advanced disease to either first-line tamoxifen therapy (202 patients, of whom 55% responded) or up-front (poly)chemotherapy (41 patients, of whom 46% responded). TP53 mutations were detected in 90 of 243 (37%) tumors, and one-fourth of these mutations resulted in a premature termination of the protein. The mutations were observed in 32% (65 of 202) of the primary tumors of tamoxifen-treated patients and in 61% (25 of 41) of the primary tumors of the chemotherapy patients. TP53 mutation was significantly associated with a poor response to tamoxifen [31% versus 66%; odds ratio (OR), 0.22; 95% confidence interval (CI), 0.12-0.42; P < 0.0001]. Patients with TP53 gene mutations in codons that directly contact DNA or with mutations in the zinc-binding dom...
Human molecular genetics, 2015
Facioscapulohumeral muscular dystrophy (FSHD: MIM#158900) is a common myopathy with marked but la... more Facioscapulohumeral muscular dystrophy (FSHD: MIM#158900) is a common myopathy with marked but largely unexplained clinical inter- and intra-familial variability. It is caused by contractions of the D4Z4 repeat array on chromosome 4 to 1-10 units (FSHD1), or by mutations in the D4Z4-binding chromatin modifier SMCHD1 (FSHD2). Both situations lead to a partial opening of the D4Z4 chromatin structure and transcription of D4Z4-encoded polyadenylated DUX4 mRNA in muscle. We measured D4Z4 CpG methylation in control, FSHD1 and FSHD2 individuals and found a significant correlation with the D4Z4 repeat array size. After correction for repeat array size, we show that the variability in clinical severity in FSHD1 and FSHD2 individuals is dependent on individual differences in susceptibility to D4Z4 hypomethylation. In FSHD1, for individuals with D4Z4 repeat arrays of 1-6 units, the clinical severity mainly depends on the size of the D4Z4 repeat. However, in individuals with arrays of 7-10 unit...
Strahlentherapie und Onkologie, 1999
A case history of unanticipated radiation-induced bilateral optic neuropathy, 18 months after ind... more A case history of unanticipated radiation-induced bilateral optic neuropathy, 18 months after induction chemotherapy and radiation therapy for a locally advanced nasopharyngeal carcinoma, is presented. Retrospective reanalysis of the radiation therapy technique, with emphasis on the doses received by the optic pathway structures, was performed. These re-calculations revealed unexpectedly high doses in the range 79 to 82 Gy (cumulative external and brachytherapy dose) at the level of the optic nerves, which explained the observed radiation injury. Routine implementation of computed tomography for 3D dose planning purposes is therefore advocated. Review of the current literature confirms the importance of 3D dose planning in avoiding this complication and high-lights the role of MRI in establishing the diagnosis of radiation-induced optic neuropathy.
Journal of Pediatric Endocrinology and Metabolism, 2000
Aarskog syndrome is an X-linked disorder characterized by faciogenital dysplasia and short statur... more Aarskog syndrome is an X-linked disorder characterized by faciogenital dysplasia and short stature. The present study set out to determine the effect of growth hormone (GH) therapy in patients with Aarskog syndrome enrolled in KIGS--the Pharmacia International Growth Database. Twenty-one patients (20 males) were evaluated. Median age at start of treatment was 8.3 years (10-90th percentiles, 5.1-14.1 years) and median height SDS was -2.8 (10-90th percentiles, -2.1 to -3.7). The median dose of GH was 0.22 mg/kg/week (10-90th percentiles, 0.15-0.30 mg/kg/week) given at a median frequency of six (4-7) times per week. Prepubertal patients were followed longitudinally for 1 year (n = 13) or 3 years (n = 7). After 1 year, the median height SDS had improved from -2.8 to -2.3 in 13 patients. After 3 years, height SDS had improved significantly (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) to -1.8 (10-90th percentiles, -2.1 to -1.1) in the seven patients. No adverse events were noted. Although final height data for these patients are still awaited, the present results support the use of GH to promote growth in children with Aarskog syndrome.
Australasian Radiology, 1992
FIGURE 1A -Contiguous axial MR images (TR 4O(hnsec, TE 15msec) through the mediastinum in a 13 ye... more FIGURE 1A -Contiguous axial MR images (TR 4O(hnsec, TE 15msec) through the mediastinum in a 13 year old female with Turner syndrome demonstrating method used to obtain aortic dimension. Aortic diameter is obtained by recording the shortest dimension of the vessel ( ...
Journal of Medical Genetics, 2004
Introduction: It has been estimated that cytogenetically visible rearrangements are present in ,1... more Introduction: It has been estimated that cytogenetically visible rearrangements are present in ,1% of newborns. These chromosomal changes can cause a wide range of deleterious developmental effects, including mental retardation (MR). It is assumed that many other cases exist where the cause is a submicroscopic deletion or duplication. To facilitate the detection of such cases, different techniques have been developed, which have differing efficiency as to the number of loci and patients that can be tested. Methods: We implemented multiplex amplifiable probe hybridisation (MAPH) to test areas known to be rearranged in MR patients (for example, subtelomeric/pericentromeric regions and those affected in microdeletion syndromes) and to look for new regions that might be related to MR. Results: In this study, over 30 000 screens for duplications and deletions were carried out; 162 different loci tested in each of 188 developmentally delayed patients. The analysis resulted in the detection of 19 rearrangements, of which ,65% would not have been detected by conventional cytogenetic analysis. A significant fraction (46%) of the rearrangements found were interstitial, despite the fact that only a limited number of these loci have so far been tested. Discussion: Our results strengthen the arguments for whole genome screening within this population, as it can be assumed that many more interstitial rearrangements would be detected. The strengths of MAPH for this analysis are the simplicity, the high throughput potential, and the high resolution of analysis. This combination should help in the future identification of the specific genes that are responsible for MR.
The Journal of Clinical Endocrinology & Metabolism, 2000
Presented is a cohort study to assess the nature and frequency of thyroid peroxidase (TPO) mutati... more Presented is a cohort study to assess the nature and frequency of thyroid peroxidase (TPO) mutations in 45 patients (35 families) with congenital hypothyroidism due to a total iodide organification defect; incidence is 1:66,000 in The Netherlands. The presentation is consistently similar with a severe form of congenital hypothyroidism and also characterized by a complete and immediate release of accumulated radioiodide from the thyroid after sodium perchlorate administration.
The Journal of Clinical Endocrinology & Metabolism, 2003
The role of GH treatment during total pubertal growth (TPG) is still unclear. We developed a pred... more The role of GH treatment during total pubertal growth (TPG) is still unclear. We developed a prediction model for TPG (centimeters) through a multiple regression analysis of various prepubertal parameters in 303 adolescents with idiopathic GH deficiency from the KIGS database. Prepubertal catch-up growth and near-adult height were achieved, and GH dose was kept constant at approximately 30 micro g/kg.d. The model was validated on a cohort of 36 patients from one center. Four TPG predictors explained 70% of the variability with an error SD of 4.2 cm: gender (TPG in males was &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;11.3 cm vs. that in females), age at onset of puberty (negative), height SD score minus midparental height SD score at puberty onset (negative), and mean GH dose during puberty (positive). Our analysis suggests that TPG in idiopathic GH deficiency is only moderately dependent on GH dose. The use of a higher GH dosage at the onset of puberty should thus depend on the individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s height development. The TPG model aids in the planning of individually optimized and cost-effective GH treatment.
Genetic Vaccines and Therapy, 2010
In recent studies, we showed that TP53 gene mutation or high levels of cytosolic vascular endothe... more In recent studies, we showed that TP53 gene mutation or high levels of cytosolic vascular endothelial growth factor (VEGF) in estrogen receptor (ER)-␣-positive primary breast tumors predict a poor disease outcome for patients treated with first-line tamoxifen for advanced disease. Mutant TP53 may up-regulate VEGF, whereas, on the other hand, wild-type TP53 may decrease VEGF production.
Developmental Neurorehabilitation, 2006
To analyse the auxological data of children with myelomeningocele (MMC) on growth hormone (GH) th... more To analyse the auxological data of children with myelomeningocele (MMC) on growth hormone (GH) therapy whose growth data was documented within KIGS (Pfizer International Growth Database). Longitudinal growth data of a sub-group of pre-pubertal children were studied after a treatment period of 3 years. Eighty patients (38 m, 42 f) with MMC with a median chronological age (CA) of 11.6 years (at latest visit) on GH were registered in the KIGS database. In 52 patients, GH deficiency was documented. GH therapy started with a median dose of 0.23 mg kg(-1) per week. The 3-year longitudinal growth was analysed in 21 patients (13 m, 8 f; median CA 9.2 years, latest visit), all of whom were pre-pubertal at start and during GH therapy. GH therapy started at 7.5 years with a dose of 0.23 mg kg(-1) per week. Birth length SDS (-0.51) and mid-parental height SDS (+0.07) were in the normal range. BMI SDS at start was +0.24, at latest visit -0.03. After a median treatment duration of 3.0 years (latest visit), height SDS improved from -2.97 (start of GH) to -2.01. The sub-group of pre-pubertal MMC patients started GH therapy (dose 0.22 mg kg(-1) per week) at 6.2 years. Growth velocity (GV) SDS increased significantly (at start: -1.77; 1 year: +2.60, 2 years: +2.25, 3 years: +1.24), thus height SDS improved from -3.25 at start to -1.87 at 36 months. BMI SDS was in the normal range and remained unchanged during GH therapy. No major side effects of GH were recorded. GH had positive effects on height SDS in MMC patients. The analysis of the longitudinal growth data of pre-pubertal MMC patients showed a significant increase in GV SDS and improvement of height SDS.
Clinical Endocrinology, 2002
The dynamics of the plasma concentrations of various diagnostic determinants of thyroid function ... more The dynamics of the plasma concentrations of various diagnostic determinants of thyroid function were analysed in children with congenital hypothyroidism (CH) after the start of T4 supplementation. The description of the biochemical dynamics of TSH and free T4 (FT4) during the first period of thyroxine treatment is important to depict the practical outlines of the initial dosage of T4 and dosage adjustments for newborns with variable forms of CH. A retrospective analysis was performed of frequent plasma TSH, total T4 (T4), FT4 and total T3 (T3) measurements in 30 CH neonates during the first weeks of treatment, treated with initial daily T4 dosages ranging from 4.8 to 11.1 microg/kg. A 50% reduction in the initial plasma TSH concentration was achieved after 3-4 days of treatment, independent of CH severity. At a median of 32 days after the start of T4 supplementation, plasma TSH ranged between 0.4 and 4.0 mU/l. The mean interval needed for FT4 to reach the age-related normal values (12-29 pmol/l) was 3 days. The increase in plasma T3 concentrations levelled off within a few days, when T4 reached concentrations of around 100 nmol/l. Plasma T3 and FT4 concentrations reach the normal range a few days after thyroxine treatment is started. By contrast, normalization of plasma TSH concentration takes several weeks. At the time that plasma TSH is normalized, CH neonates show a higher range of plasma FT4 concentrations than the normal range. When TSH normalization is the goal of treatment in CH, the target range for plasma FT4 during treatment in the first months needs to be adapted. During the first month of treatment the plasma TSH concentration is not helpful in assessing the proper T4 supplementation dosage. Once plasma TSH has reached normal values, it becomes a reliable determinant in addition to plasma FT4.
Nature Genetics, 2013
l e t t e r s We report the results of an association study of melanoma that is based on the geno... more l e t t e r s We report the results of an association study of melanoma that is based on the genome-wide imputation of the genotypes of 1,353 cases and 3,566 controls of European origin conducted by the GenoMEL consortium. This revealed an association between several SNPs in intron 8 of the FTO gene, including rs16953002, which replicated using 12,313 cases and 55,667 controls of European ancestry from Europe, the USA and Australia (combined P = 3.6 × 10 −12 , per-allele odds ratio for allele A = 1.16). In addition to identifying a new melanomasusceptibility locus, this is to our knowledge the first study to identify and replicate an association with SNPs in FTO not related to body mass index (BMI). These SNPs are not in intron 1 (the BMI-related region) and exhibit no association with BMI. This suggests FTO's function may be broader than the existing paradigm that FTO variants influence multiple traits only through their associations with BMI and obesity.
Brain, 2014
Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorder... more Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorders, such as Alzheimer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease, frontotemporal dementia and Parkinson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease, and is also characteristic of neuronal intermediate filament inclusion disease. Intermediate filaments type IV include three neurofilament proteins (light, medium and heavy molecular weight neurofilament subunits) and α-internexin. The phosphorylation of intermediate filament proteins contributes to axonal growth, and is regulated by protein kinase A. Here we describe a family with a novel late-onset neurodegenerative disorder presenting with dementia and/or parkinsonism in 12 affected individuals. The disorder is characterized by a unique neuropathological phenotype displaying abundant neuronal inclusions by haematoxylin and eosin staining throughout the brain with immunoreactivity for intermediate filaments. Combining linkage analysis, exome sequencing and proteomics analysis, we identified a heterozygous c.149T&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;G (p.Leu50Arg) missense mutation in the gene encoding the protein kinase A type I-beta regulatory subunit (PRKAR1B). The pathogenicity of the mutation is supported by segregation in the family, absence in variant databases, and the specific accumulation of PRKAR1B in the inclusions in our cases associated with a specific biochemical pattern of PRKAR1B. Screening of PRKAR1B in 138 patients with Parkinson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease and 56 patients with frontotemporal dementia did not identify additional novel pathogenic mutations. Our findings link a pathogenic PRKAR1B mutation to a novel hereditary neurodegenerative disorder and suggest an altered protein kinase A function through a reduced binding of the regulatory subunit to the A-kinase anchoring protein and the catalytic subunit of protein kinase A, which might result in subcellular dislocalization of the catalytic subunit and hyperphosphorylation of intermediate filaments.
Journal of the Neurological Sciences, 2009
The American Journal of Human Genetics, 1999
Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the her... more Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the hereditary multiple exostoses syndrome (EXT). Approximately 15% of all chondrosarcomas arise within the cartilaginous cap of an osteochondroma. EXT is genetically heterogeneous, and two genes, EXT1 and EXT2, located on 8q24 and 11p11-p12, respectively, have been cloned. It is still unclear whether osteochondroma is a developmental disorder or a true neoplasm. Furthermore, it is unclear whether inactivation of both alleles of an EXT gene, according to the tumor-suppressor model, is required for osteochondroma development, or whether a single EXT germline mutation acts in a dominant negative way. We therefore studied loss of heterozygosity and DNA ploidy in eight sporadic and six hereditary osteochondromas. EXT1-and EXT2-mutation analysis was performed in a total of 34 sporadic and hereditary osteochondromas and secondary peripheral chondrosarcomas. We demonstrated osteochondroma to be a true neoplasm, since aneuploidy was found in 4 of 10 osteochondromas. Furthermore, LOH was almost exclusively found at the EXT1 locus in 5 of 14 osteochondromas. Four novel constitutional cDNA alterations were detected in exon 1 of EXT1. Two patients with multiple osteochondromas demonstrated a germline mutation combined with loss of the remaining wild-type allele in three osteochondromas, indicating that, in cartilaginous cells of the growth plate, inactivation of both copies of the EXT1 gene is required for osteochondroma formation in hereditary cases. In contrast, no somatic EXT1 cDNA alterations were found in sporadic osteochondromas. No mutations were found in the EXT2 gene.
Research in Immunology, 1998
The POU homeodomain containing transcriptional activator POU1F1, formerly called Pit1 or GHF-1, i... more The POU homeodomain containing transcriptional activator POU1F1, formerly called Pit1 or GHF-1, is required for the embry- ological determination and postnatal secretory function of the GH-, PRL-, and TSH-producing cells in the anterior pituitary. Several mutations in the gene encoding POU1F1 have been described, re- sulting in a syndrome of combined pituitary hormone deficiency in- volving these three hormones. Most
Human Mutation, 2015
Facioscapulohumeral muscular dystrophy (FSHD) is most often associated with variegated expression... more Facioscapulohumeral muscular dystrophy (FSHD) is most often associated with variegated expression in somatic cells of the normally repressed DUX4 gene within the D4Z4 repeat array. The most common form, FSHD1, is caused by a D4Z4 repeat array contraction to a size of 1-10 units (normal range 10-100 units). The less common form, FSHD2, is characterized by D4Z4 CpG hypomethylation and is most often caused by loss of function mutations in the structural maintenance of chromosomes hinge domain 1 (SMCHD1) gene on chromosome 18p. The chromatin modifier SMCHD1 is necessary to maintain a repressed D4Z4 chromatin state. Here we describe two FSHD2 families with a 1.2 Mb deletion encompassing the SMCHD1 gene. Numerical aberrations of chromosome 18 are relatively common and the majority of 18p deletion syndrome (18p-) cases have, like these FSHD2 families, only one copy of SMCHD1. Our finding therefore raises the possibility that 18p- cases are at risk of developing FSHD. To address this possibility, we combined genome wide array analysis data with D4Z4 CpG methylation and repeat array sizes in individuals with 18p- and conclude that approximately 1:8 18p- cases might be at risk of developing FSHD. This article is protected by copyright. All rights reserved.
Cancer research, Jan 15, 2000
TP53 has been implicated in regulation of the cell cycle, DNA repair, and apoptosis. We studied, ... more TP53 has been implicated in regulation of the cell cycle, DNA repair, and apoptosis. We studied, in primary breast tumors through direct cDNA sequencing of exons 2-11, whether TP53 gene mutations can predict response in patients with advanced disease to either first-line tamoxifen therapy (202 patients, of whom 55% responded) or up-front (poly)chemotherapy (41 patients, of whom 46% responded). TP53 mutations were detected in 90 of 243 (37%) tumors, and one-fourth of these mutations resulted in a premature termination of the protein. The mutations were observed in 32% (65 of 202) of the primary tumors of tamoxifen-treated patients and in 61% (25 of 41) of the primary tumors of the chemotherapy patients. TP53 mutation was significantly associated with a poor response to tamoxifen [31% versus 66%; odds ratio (OR), 0.22; 95% confidence interval (CI), 0.12-0.42; P < 0.0001]. Patients with TP53 gene mutations in codons that directly contact DNA or with mutations in the zinc-binding dom...
Human molecular genetics, 2015
Facioscapulohumeral muscular dystrophy (FSHD: MIM#158900) is a common myopathy with marked but la... more Facioscapulohumeral muscular dystrophy (FSHD: MIM#158900) is a common myopathy with marked but largely unexplained clinical inter- and intra-familial variability. It is caused by contractions of the D4Z4 repeat array on chromosome 4 to 1-10 units (FSHD1), or by mutations in the D4Z4-binding chromatin modifier SMCHD1 (FSHD2). Both situations lead to a partial opening of the D4Z4 chromatin structure and transcription of D4Z4-encoded polyadenylated DUX4 mRNA in muscle. We measured D4Z4 CpG methylation in control, FSHD1 and FSHD2 individuals and found a significant correlation with the D4Z4 repeat array size. After correction for repeat array size, we show that the variability in clinical severity in FSHD1 and FSHD2 individuals is dependent on individual differences in susceptibility to D4Z4 hypomethylation. In FSHD1, for individuals with D4Z4 repeat arrays of 1-6 units, the clinical severity mainly depends on the size of the D4Z4 repeat. However, in individuals with arrays of 7-10 unit...
Strahlentherapie und Onkologie, 1999
A case history of unanticipated radiation-induced bilateral optic neuropathy, 18 months after ind... more A case history of unanticipated radiation-induced bilateral optic neuropathy, 18 months after induction chemotherapy and radiation therapy for a locally advanced nasopharyngeal carcinoma, is presented. Retrospective reanalysis of the radiation therapy technique, with emphasis on the doses received by the optic pathway structures, was performed. These re-calculations revealed unexpectedly high doses in the range 79 to 82 Gy (cumulative external and brachytherapy dose) at the level of the optic nerves, which explained the observed radiation injury. Routine implementation of computed tomography for 3D dose planning purposes is therefore advocated. Review of the current literature confirms the importance of 3D dose planning in avoiding this complication and high-lights the role of MRI in establishing the diagnosis of radiation-induced optic neuropathy.
Journal of Pediatric Endocrinology and Metabolism, 2000
Aarskog syndrome is an X-linked disorder characterized by faciogenital dysplasia and short statur... more Aarskog syndrome is an X-linked disorder characterized by faciogenital dysplasia and short stature. The present study set out to determine the effect of growth hormone (GH) therapy in patients with Aarskog syndrome enrolled in KIGS--the Pharmacia International Growth Database. Twenty-one patients (20 males) were evaluated. Median age at start of treatment was 8.3 years (10-90th percentiles, 5.1-14.1 years) and median height SDS was -2.8 (10-90th percentiles, -2.1 to -3.7). The median dose of GH was 0.22 mg/kg/week (10-90th percentiles, 0.15-0.30 mg/kg/week) given at a median frequency of six (4-7) times per week. Prepubertal patients were followed longitudinally for 1 year (n = 13) or 3 years (n = 7). After 1 year, the median height SDS had improved from -2.8 to -2.3 in 13 patients. After 3 years, height SDS had improved significantly (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) to -1.8 (10-90th percentiles, -2.1 to -1.1) in the seven patients. No adverse events were noted. Although final height data for these patients are still awaited, the present results support the use of GH to promote growth in children with Aarskog syndrome.
Australasian Radiology, 1992
FIGURE 1A -Contiguous axial MR images (TR 4O(hnsec, TE 15msec) through the mediastinum in a 13 ye... more FIGURE 1A -Contiguous axial MR images (TR 4O(hnsec, TE 15msec) through the mediastinum in a 13 year old female with Turner syndrome demonstrating method used to obtain aortic dimension. Aortic diameter is obtained by recording the shortest dimension of the vessel ( ...
Journal of Medical Genetics, 2004
Introduction: It has been estimated that cytogenetically visible rearrangements are present in ,1... more Introduction: It has been estimated that cytogenetically visible rearrangements are present in ,1% of newborns. These chromosomal changes can cause a wide range of deleterious developmental effects, including mental retardation (MR). It is assumed that many other cases exist where the cause is a submicroscopic deletion or duplication. To facilitate the detection of such cases, different techniques have been developed, which have differing efficiency as to the number of loci and patients that can be tested. Methods: We implemented multiplex amplifiable probe hybridisation (MAPH) to test areas known to be rearranged in MR patients (for example, subtelomeric/pericentromeric regions and those affected in microdeletion syndromes) and to look for new regions that might be related to MR. Results: In this study, over 30 000 screens for duplications and deletions were carried out; 162 different loci tested in each of 188 developmentally delayed patients. The analysis resulted in the detection of 19 rearrangements, of which ,65% would not have been detected by conventional cytogenetic analysis. A significant fraction (46%) of the rearrangements found were interstitial, despite the fact that only a limited number of these loci have so far been tested. Discussion: Our results strengthen the arguments for whole genome screening within this population, as it can be assumed that many more interstitial rearrangements would be detected. The strengths of MAPH for this analysis are the simplicity, the high throughput potential, and the high resolution of analysis. This combination should help in the future identification of the specific genes that are responsible for MR.
The Journal of Clinical Endocrinology & Metabolism, 2000
Presented is a cohort study to assess the nature and frequency of thyroid peroxidase (TPO) mutati... more Presented is a cohort study to assess the nature and frequency of thyroid peroxidase (TPO) mutations in 45 patients (35 families) with congenital hypothyroidism due to a total iodide organification defect; incidence is 1:66,000 in The Netherlands. The presentation is consistently similar with a severe form of congenital hypothyroidism and also characterized by a complete and immediate release of accumulated radioiodide from the thyroid after sodium perchlorate administration.
The Journal of Clinical Endocrinology & Metabolism, 2003
The role of GH treatment during total pubertal growth (TPG) is still unclear. We developed a pred... more The role of GH treatment during total pubertal growth (TPG) is still unclear. We developed a prediction model for TPG (centimeters) through a multiple regression analysis of various prepubertal parameters in 303 adolescents with idiopathic GH deficiency from the KIGS database. Prepubertal catch-up growth and near-adult height were achieved, and GH dose was kept constant at approximately 30 micro g/kg.d. The model was validated on a cohort of 36 patients from one center. Four TPG predictors explained 70% of the variability with an error SD of 4.2 cm: gender (TPG in males was &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;11.3 cm vs. that in females), age at onset of puberty (negative), height SD score minus midparental height SD score at puberty onset (negative), and mean GH dose during puberty (positive). Our analysis suggests that TPG in idiopathic GH deficiency is only moderately dependent on GH dose. The use of a higher GH dosage at the onset of puberty should thus depend on the individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s height development. The TPG model aids in the planning of individually optimized and cost-effective GH treatment.
Genetic Vaccines and Therapy, 2010
In recent studies, we showed that TP53 gene mutation or high levels of cytosolic vascular endothe... more In recent studies, we showed that TP53 gene mutation or high levels of cytosolic vascular endothelial growth factor (VEGF) in estrogen receptor (ER)-␣-positive primary breast tumors predict a poor disease outcome for patients treated with first-line tamoxifen for advanced disease. Mutant TP53 may up-regulate VEGF, whereas, on the other hand, wild-type TP53 may decrease VEGF production.
Developmental Neurorehabilitation, 2006
To analyse the auxological data of children with myelomeningocele (MMC) on growth hormone (GH) th... more To analyse the auxological data of children with myelomeningocele (MMC) on growth hormone (GH) therapy whose growth data was documented within KIGS (Pfizer International Growth Database). Longitudinal growth data of a sub-group of pre-pubertal children were studied after a treatment period of 3 years. Eighty patients (38 m, 42 f) with MMC with a median chronological age (CA) of 11.6 years (at latest visit) on GH were registered in the KIGS database. In 52 patients, GH deficiency was documented. GH therapy started with a median dose of 0.23 mg kg(-1) per week. The 3-year longitudinal growth was analysed in 21 patients (13 m, 8 f; median CA 9.2 years, latest visit), all of whom were pre-pubertal at start and during GH therapy. GH therapy started at 7.5 years with a dose of 0.23 mg kg(-1) per week. Birth length SDS (-0.51) and mid-parental height SDS (+0.07) were in the normal range. BMI SDS at start was +0.24, at latest visit -0.03. After a median treatment duration of 3.0 years (latest visit), height SDS improved from -2.97 (start of GH) to -2.01. The sub-group of pre-pubertal MMC patients started GH therapy (dose 0.22 mg kg(-1) per week) at 6.2 years. Growth velocity (GV) SDS increased significantly (at start: -1.77; 1 year: +2.60, 2 years: +2.25, 3 years: +1.24), thus height SDS improved from -3.25 at start to -1.87 at 36 months. BMI SDS was in the normal range and remained unchanged during GH therapy. No major side effects of GH were recorded. GH had positive effects on height SDS in MMC patients. The analysis of the longitudinal growth data of pre-pubertal MMC patients showed a significant increase in GV SDS and improvement of height SDS.
Clinical Endocrinology, 2002
The dynamics of the plasma concentrations of various diagnostic determinants of thyroid function ... more The dynamics of the plasma concentrations of various diagnostic determinants of thyroid function were analysed in children with congenital hypothyroidism (CH) after the start of T4 supplementation. The description of the biochemical dynamics of TSH and free T4 (FT4) during the first period of thyroxine treatment is important to depict the practical outlines of the initial dosage of T4 and dosage adjustments for newborns with variable forms of CH. A retrospective analysis was performed of frequent plasma TSH, total T4 (T4), FT4 and total T3 (T3) measurements in 30 CH neonates during the first weeks of treatment, treated with initial daily T4 dosages ranging from 4.8 to 11.1 microg/kg. A 50% reduction in the initial plasma TSH concentration was achieved after 3-4 days of treatment, independent of CH severity. At a median of 32 days after the start of T4 supplementation, plasma TSH ranged between 0.4 and 4.0 mU/l. The mean interval needed for FT4 to reach the age-related normal values (12-29 pmol/l) was 3 days. The increase in plasma T3 concentrations levelled off within a few days, when T4 reached concentrations of around 100 nmol/l. Plasma T3 and FT4 concentrations reach the normal range a few days after thyroxine treatment is started. By contrast, normalization of plasma TSH concentration takes several weeks. At the time that plasma TSH is normalized, CH neonates show a higher range of plasma FT4 concentrations than the normal range. When TSH normalization is the goal of treatment in CH, the target range for plasma FT4 during treatment in the first months needs to be adapted. During the first month of treatment the plasma TSH concentration is not helpful in assessing the proper T4 supplementation dosage. Once plasma TSH has reached normal values, it becomes a reliable determinant in addition to plasma FT4.
Nature Genetics, 2013
l e t t e r s We report the results of an association study of melanoma that is based on the geno... more l e t t e r s We report the results of an association study of melanoma that is based on the genome-wide imputation of the genotypes of 1,353 cases and 3,566 controls of European origin conducted by the GenoMEL consortium. This revealed an association between several SNPs in intron 8 of the FTO gene, including rs16953002, which replicated using 12,313 cases and 55,667 controls of European ancestry from Europe, the USA and Australia (combined P = 3.6 × 10 −12 , per-allele odds ratio for allele A = 1.16). In addition to identifying a new melanomasusceptibility locus, this is to our knowledge the first study to identify and replicate an association with SNPs in FTO not related to body mass index (BMI). These SNPs are not in intron 1 (the BMI-related region) and exhibit no association with BMI. This suggests FTO's function may be broader than the existing paradigm that FTO variants influence multiple traits only through their associations with BMI and obesity.