Carlo Marcelis - Academia.edu (original) (raw)

Papers by Carlo Marcelis

European Journal of Medical Genetics, 2015

Tricho-rhino-phalangeal syndrome (TRPS) is characterized by craniofacial and skeletal abnormaliti... more Tricho-rhino-phalangeal syndrome (TRPS) is characterized by craniofacial and skeletal abnormalities, and subdivided in TRPS I, caused by mutations in TRPS1, and TRPS II, caused by a contiguous gene deletion affecting (amongst others) TRPS1 and EXT1. We performed a collaborative international study to delineate phenotype, natural history, variability, and genotypeephenotype correlations in more detail.

From data collected via a large international collaborative study, we have constructed a growth c... more From data collected via a large international collaborative study, we have constructed a growth chart for patients with molecularly confirmed congenital spondylo-epiphyseal dysplasia (SEDC) and other COL2A1 related dysplasias. The growth chart is based on longitudinal height measurements of 79 patients with glycine substitutions in the triple-helical domain of COL2A1. In addition, measurements of 27 patients with other molecular defects, such as arginine to cysteine substitutions, splice mutations, and mutations in the C-terminal propeptide have been plotted on the chart. Height of the patients progressively deviate from that of normal children: compared to normal WHO charts, the mean length/height is -2.6 SD at birth, -4.2 SD at 5 years, and -5.8 SD in adulthood. The mean adult height (male and female combined) of patients with glycine substitutions in the triple-helical region is 138.2 cm but there is a large variation. Patients with glycine to cysteine substitutions tend to cluster within the upper part of the chart, while patients with glycine to serine or valine substitutions are situated between +1 SD and -1 SD. Patients with carboxy-terminal glycine substitutions tend to be shorter than patients with amino-terminal substitutions, while patients with splice mutations are relatively tall. However, there are exceptions and specific mutations can have a strong or a relatively mild negative effect on growth. The observation of significant difference in adult height between affected members of the same family indicates that height remains a multifactorial trait even in the presence of a mutation with a strong dominant effect.

Objectives: Osteoporosis with fractures as an X-linked trait, was first reported as a rare type o... more Objectives: Osteoporosis with fractures as an X-linked trait, was first reported as a rare type of OI by Sillence in 1980. OI is genetically heterogeneous with an estimated 90% due to dominant mutations in the COL1A1 or COL1A2 gene and approximately 10% due to recessive mutations and other unknown causes. Our goal is to discover new genetic causes of OI and related disorders. Methods: We investigated all referred cases that had been clearly labelled as OI (all types) but where no genetic cause had been identified by sequence analysis of all known OI genes. Depending on the pedigree, specific genetic methods including exome sequencing were used to identify the causative gene. Results: In one large family with a referral diagnosis of OI type I, normal collagen type I electrophoresis and absence of COL1A1/2 mutations, X-linked inheritance appeared likely based on the pedigree. Exome sequencing of the X chromosome identified a putative pathogenic frameshift mutation in a candidate gene ...

Osteoporosis with its consequences, i.e., fractures, is major health problem in ageing societies.... more Osteoporosis with its consequences, i.e., fractures, is major health problem in ageing societies. As osteoporosis is a prevalent disorder, understanding its etiological factors is very important. We recently identified novel pathogenic variants in PLS3 (encoding Plastin 3 (PLS3), a filamentous-actin bundling protein) as a cause of X-linked osteoporosis and osteoporotic fractures in five Dutch families (van Dijk et al. NEJM 2013:369(16):1529-36). These loss-of-function variants cause decreased bone mineral density and increased risk of fracture in hemizygous young men whereas the clinical picture in heterozygous women ranged from asymptomatic to early-onset osteoporosis. It was highly unexpected that mutations in this gene would cause osteoporosis and fractures as it had never been described as a candidate gene for osteoporosis nor was it known to play a role in bone formation. However, results of in vivo analyses in zebrafish strongly supported a role for PLS3 as a bone regulatory p...

Birth defects research. Part C, Embryo today : reviews, 2014

Congenital anorectal malformations (ARMs) are one of the most frequently observed birth defects o... more Congenital anorectal malformations (ARMs) are one of the most frequently observed birth defects of the digestive system. However, their etiology remains elusive. Therefore, we aim to summarize and critically appraise all existing literature on the genetic and nongenetic etiology of nonsyndromic ARM and to conclude with unifying hypotheses and directions for future research. A structured literature search on English language human studies was conducted in PubMed and Embase up to October 1, 2013, resulting in 112 included articles. Research on the identification of genes underlying nonsyndromic ARM is remarkably scarce. Most studies were focused on screening of candidate genes for mutations or single-nucleotide polymorphisms, which did not yield any substantial evidence. Nongenetic factors fairly consistently found to be associated with ARM are assisted reproductive techniques, multiple pregnancy, preterm delivery, low birth weight, maternal overweight or obesity, and preexisting diab...

European Journal of Pediatrics, 2014

Anorectal malformations (ARM) are rare congenital malformations of the gastrointestinal tract. Ap... more Anorectal malformations (ARM) are rare congenital malformations of the gastrointestinal tract. Approximately 60 % of the patients have additional congenital malformations, such as hypospadias. A recently published article showed that deletion of one single gene, dickkopf WNT signaling pathway inhibitor-1 (Dkk1), resulted in an imperforate anus with rectourinary fistula and preputial hypospadias in mice. To determine whether DKK1 also plays a role in the etiology of ARM and hypospadias in humans, we sequenced the four exons of the DKK1 gene in 17 patients affected with both ARM and hypospadias. No new potential disease-causing variant was identified. However, we detected a known non-synonymous variant in one patient, which was predicted in silico to be damaging, and the corresponding unaffected amino acid is highly conserved. Conclusion: In this human study, a potential interesting non-synonymous variant was found in the DKK1 gene. Whether this variant plays a contributory role in the genesis of ARM or hypospadias would require a much larger study.

although the majority displayed various degrees of developmental delay and speech disturbances. O... more although the majority displayed various degrees of developmental delay and speech disturbances. Other clinical features included behavioral problems, hypotonia, and dysmorphic facial features. Notably, none of the patients was diagnosed with a congenital heart defect. We found a high degree of inherited duplications. Additional copy number changes of unclear clinical significance were identified in 5 of our patients, and it is possible that these may contribute to the phenotypic expression in these patients as has been suggested recently in a 2-hit 'digenic' model for 16p12.1 deletions. The varied phenotypic expression and incomplete penetrance observed for distal 22q11.2 duplications makes it exceedingly difficult to ascribe pathogenicity for these duplications. Given the observed enrichment of the duplication in patient samples versus healthy controls, it is likely that distal 22q11.2 duplications represent a susceptibility/risk locus for speech and mild developmental delay.

Birth Defects Research Part A: Clinical and Molecular Teratology, 2014

Both genetic and nongenetic factors are suggested to be involved in the etiology of congenital an... more Both genetic and nongenetic factors are suggested to be involved in the etiology of congenital anorectal malformations (ARM). Maternal periconceptional use of folic acid supplements were inconsistently suggested to play a role in the prevention of ARM. Therefore, we investigated independent associations and interactions of maternal periconceptional folic acid supplement use and the infant and maternal MTHFR (methylenetetrahydrofolate reductase) C677T polymorphisms with the risk of ARM and subgroups of ARM. A case-control study was conducted among 371 nonsyndromic ARM cases and 714 population-based controls born between 1990 and 2012 using maternal questionnaires and DNA samples from mother and child. Cases were treated for ARM at departments of Pediatric Surgery of the Radboud university medical center, Sophia Children's Hospital-Erasmus MC Rotterdam, and the University Medical Center Groningen in The Netherlands and hospitals throughout Germany. No association with folic acid use was present (odds ratio = 1.1; 95% confidence interval: 0.8-1.4) for ARM as a group. Infant and maternal MTHFR C677T polymorphisms were weakly associated with isolated ARM in particular. Lack of folic acid supplement use in combination with infants or mothers carrying the MTHFR C677T polymorphism did not seem to increase the risk of ARM or subgroups of ARM. The relative excess risks due to interaction did not clearly indicate interaction on an additive scale either. This first study investigating interactions between periconceptional folic acid supplement use and infant and maternal MTHFR C677T polymorphisms in the etiology of ARM did not provide evidence for a role of this gene-environment interaction.

Pediatric Surgery International, 2010

Purpose The recently established International Consortium on Anorectal Malformations aims to iden... more Purpose The recently established International Consortium on Anorectal Malformations aims to identify genetic and environmental risk factors in the etiology of syndromic and nonsyndromic anorectal malformations (ARM) by promoting collaboration through data sharing and combined research activities.

Orphanet Journal of Rare Diseases, 2011

Background: The kyphoscoliotic type of Ehlers-Danlos syndrome (EDS VIA) (OMIM 225400) is a rare i... more Background: The kyphoscoliotic type of Ehlers-Danlos syndrome (EDS VIA) (OMIM 225400) is a rare inheritable connective tissue disorder characterized by a deficiency of collagen lysyl hydroxylase 1 (LH1; EC 1.14.11.4) due to mutations in PLOD1. Biochemically this results in underhydroxylation of collagen lysyl residues and, hence, an abnormal pattern of lysyl pyridinoline (LP) and hydroxylysyl pyridinoline (HP) crosslinks excreted in the urine. Clinically the disorder is characterized by hypotonia and kyphoscoliosis at birth, joint hypermobility, and skin hyperelasticity and fragility. Severe hypotonia usually leads to delay in gross motor development, whereas cognitive development is reported to be normal. Methods: We describe the clinical, biochemical and molecular characterisation, as well as electron microscopy findings of skin, in 15 patients newly diagnosed with this rare type of Ehlers-Danlos syndrome.

New England Journal of Medicine, 2013

Kidney International, 2013

Journal of Medical Genetics, 2008

Patients with a microscopically visible deletion of the distal part of the long arm of chromosome... more Patients with a microscopically visible deletion of the distal part of the long arm of chromosome 1 have a recognisable phenotype, including mental retardation, microcephaly, growth retardation, a distinct facial appearance and various midline defects including corpus callosum abnormalities, cardiac, gastro-oesophageal and urogenital defects, as well as various central nervous system anomalies. Patients with a submicroscopic, subtelomeric 1qter deletion have a similar phenotype, suggesting that the main phenotype of these patients is caused by haploinsufficiency of genes in this region. To describe the clinical presentation of 13 new patients with a submicroscopic deletion of 1q43q44, of which nine were interstitial, and to report on the molecular characterisation of the deletion size. The clinical presentation of these patients has clear similarities with previously reported cases with a terminal 1q deletion. Corpus callosum abnormalities were present in 10 of our patients. The AKT3 gene has been reported as an important candidate gene causing this abnormality. However, through detailed molecular analysis of the deletion sizes in our patient cohort, we were able to delineate the critical region for corpus callosum abnormalities to a 360 kb genomic segment which contains four possible candidate genes, but excluding the AKT3 gene.

Journal of Medical Genetics, 2009

Journal of Medical Genetics, 2010

Mutations in TRPV4, a gene that encodes a Ca(2+) permeable non-selective cation channel, have rec... more Mutations in TRPV4, a gene that encodes a Ca(2+) permeable non-selective cation channel, have recently been found in a spectrum of skeletal dysplasias that includes brachyolmia, spondylometaphyseal dysplasia, Kozlowski type (SMDK) and metatropic dysplasia (MD). Only a total of seven missense mutations were detected, however. The full spectrum of TRPV4 mutations and their phenotypes remained unclear. To examine TRPV4 mutation spectrum and phenotype-genotype association, we searched for TRPV4 mutations by PCR-direct sequencing from genomic DNA in 22 MD and 20 SMDK probands. TRPV4 mutations were found in all but one MD subject. In total, 19 different heterozygous mutations were identified in 41 subjects; two were recurrent and 17 were novel. In MD, a recurrent P799L mutation was identified in nine subjects, as well as 10 novel mutations including F471del, the first deletion mutation of TRPV4. In SMDK, a recurrent R594H mutation was identified in 12 subjects and seven novel mutations. An association between the position of mutations and the disease phenotype was also observed. Thus, P799 in exon 15 is a hot codon for MD mutations, as four different amino acid substitutions have been observed at this codon; while R594 in exon 11 is a hotspot for SMDK mutations. The TRPV4 mutation spectrum in MD and SMDK, which showed genotype-phenotype correlation and potential functional significance of mutations that are non-randomly distributed over the gene, was presented in this study. The results would help diagnostic laboratories establish efficient screening strategies for genetic diagnosis of the TRPV4 dysplasia family diseases.

Journal of Cellular and Molecular Medicine, 2009

Mutations in the LMNA gene [MIM 150330] cause a wide variety of inherited disorders called lamino... more Mutations in the LMNA gene [MIM 150330] cause a wide variety of inherited disorders called laminopathies that affect bone, fat, heart, nervous system, skeletal muscle and skin (reviewed in ). Lamins are intermediate filament proteins with N-and C-terminal regions flanking an ␣-helical rod domain. This structure

Human Mutation, 2013

The advent of massive parallel sequencing is rapidly changing the strategies employed for the gen... more The advent of massive parallel sequencing is rapidly changing the strategies employed for the genetic diagnosis and research of rare diseases that involve a large number of genes. So far it is not clear whether these approaches perform significantly better than conventional single gene testing as requested by clinicians. The current yield of this traditional diagnostic approach depends on a complex of factors that include gene-specific phenotype traits, and the relative frequency of the involvement of specific genes. To gauge the impact of the paradigm shift that is occurring in molecular diagnostics, we assessed traditional Sanger-based sequencing (in 2011) and exome sequencing followed by targeted bioinformatics analysis (in 2012) for five different conditions that are highly heterogeneous, and for which our center provides molecular diagnosis. We find that exome sequencing has a much higher diagnostic yield than Sanger sequencing for deafness, blindness, mitochondrial disease, and movement disorders. For microsatellite-stable colorectal cancer, this was low under both strategies. Even if all genes that could have been ordered by physicians had been tested, the larger number of genes captured by the exome would still have led to a clearly superior diagnostic yield at a fraction of the cost.

Human Mutation, 2008

Feingold syndrome (FS) is the most frequent cause of familial syndromic gastrointestinal atresia ... more Feingold syndrome (FS) is the most frequent cause of familial syndromic gastrointestinal atresia and follows autosomal dominant inheritance. FS is caused by germline mutations in or deletions of the MYCN gene. Previously, 12 different heterozygous MYCN mutations and two deletions containing multiple genes including MYCN were described. All these mutations result in haploinsufficiency of both the canonical MYCN protein and the shorter isoform, DMYCN. We report 11 novel mutations including seven mutations in exon 2 that result in a premature termination codon (PTC) in the long MYCN transcript. Moreover, we have identified a PTC in exon 1 that only affects the DMYCN isoform, without a phenotypic effect. This suggests that mutations in only DMYCN do not contribute to the FS. Additionally, we found three novel deletions encompassing MYCN. Together with our previous report we now have a total of four missense mutations in the DNA binding domain, 19 PTCs of which six render the transcript subject to nonsense-mediated decay (NMD), and five larger deletions in a total of 77 patients. We have reviewed the clinical features of these patients, and found that digital anomalies, e.g., brachymesophalangy and toe syndactyly, are the most consistent features, present in 100% and 97% of the patients, respectively. Small head circumference was present in 89% of the cases. Gastrointestinal atresia remains the most important major congenital anomaly (55%), but cardiac and renal anomalies are also frequent. We suggest that the presence of brachymesophalangy and toe syndactyly in combination with microcephaly is enough to justify MYCN analysis. Hum Mutat 29(9), 1125-1132, 2008. r r 2008 Wiley-Liss, Inc.

European Journal of Medical Genetics, 2015

Tricho-rhino-phalangeal syndrome (TRPS) is characterized by craniofacial and skeletal abnormaliti... more Tricho-rhino-phalangeal syndrome (TRPS) is characterized by craniofacial and skeletal abnormalities, and subdivided in TRPS I, caused by mutations in TRPS1, and TRPS II, caused by a contiguous gene deletion affecting (amongst others) TRPS1 and EXT1. We performed a collaborative international study to delineate phenotype, natural history, variability, and genotypeephenotype correlations in more detail.

From data collected via a large international collaborative study, we have constructed a growth c... more From data collected via a large international collaborative study, we have constructed a growth chart for patients with molecularly confirmed congenital spondylo-epiphyseal dysplasia (SEDC) and other COL2A1 related dysplasias. The growth chart is based on longitudinal height measurements of 79 patients with glycine substitutions in the triple-helical domain of COL2A1. In addition, measurements of 27 patients with other molecular defects, such as arginine to cysteine substitutions, splice mutations, and mutations in the C-terminal propeptide have been plotted on the chart. Height of the patients progressively deviate from that of normal children: compared to normal WHO charts, the mean length/height is -2.6 SD at birth, -4.2 SD at 5 years, and -5.8 SD in adulthood. The mean adult height (male and female combined) of patients with glycine substitutions in the triple-helical region is 138.2 cm but there is a large variation. Patients with glycine to cysteine substitutions tend to cluster within the upper part of the chart, while patients with glycine to serine or valine substitutions are situated between +1 SD and -1 SD. Patients with carboxy-terminal glycine substitutions tend to be shorter than patients with amino-terminal substitutions, while patients with splice mutations are relatively tall. However, there are exceptions and specific mutations can have a strong or a relatively mild negative effect on growth. The observation of significant difference in adult height between affected members of the same family indicates that height remains a multifactorial trait even in the presence of a mutation with a strong dominant effect.

Objectives: Osteoporosis with fractures as an X-linked trait, was first reported as a rare type o... more Objectives: Osteoporosis with fractures as an X-linked trait, was first reported as a rare type of OI by Sillence in 1980. OI is genetically heterogeneous with an estimated 90% due to dominant mutations in the COL1A1 or COL1A2 gene and approximately 10% due to recessive mutations and other unknown causes. Our goal is to discover new genetic causes of OI and related disorders. Methods: We investigated all referred cases that had been clearly labelled as OI (all types) but where no genetic cause had been identified by sequence analysis of all known OI genes. Depending on the pedigree, specific genetic methods including exome sequencing were used to identify the causative gene. Results: In one large family with a referral diagnosis of OI type I, normal collagen type I electrophoresis and absence of COL1A1/2 mutations, X-linked inheritance appeared likely based on the pedigree. Exome sequencing of the X chromosome identified a putative pathogenic frameshift mutation in a candidate gene ...

Osteoporosis with its consequences, i.e., fractures, is major health problem in ageing societies.... more Osteoporosis with its consequences, i.e., fractures, is major health problem in ageing societies. As osteoporosis is a prevalent disorder, understanding its etiological factors is very important. We recently identified novel pathogenic variants in PLS3 (encoding Plastin 3 (PLS3), a filamentous-actin bundling protein) as a cause of X-linked osteoporosis and osteoporotic fractures in five Dutch families (van Dijk et al. NEJM 2013:369(16):1529-36). These loss-of-function variants cause decreased bone mineral density and increased risk of fracture in hemizygous young men whereas the clinical picture in heterozygous women ranged from asymptomatic to early-onset osteoporosis. It was highly unexpected that mutations in this gene would cause osteoporosis and fractures as it had never been described as a candidate gene for osteoporosis nor was it known to play a role in bone formation. However, results of in vivo analyses in zebrafish strongly supported a role for PLS3 as a bone regulatory p...

Birth defects research. Part C, Embryo today : reviews, 2014

Congenital anorectal malformations (ARMs) are one of the most frequently observed birth defects o... more Congenital anorectal malformations (ARMs) are one of the most frequently observed birth defects of the digestive system. However, their etiology remains elusive. Therefore, we aim to summarize and critically appraise all existing literature on the genetic and nongenetic etiology of nonsyndromic ARM and to conclude with unifying hypotheses and directions for future research. A structured literature search on English language human studies was conducted in PubMed and Embase up to October 1, 2013, resulting in 112 included articles. Research on the identification of genes underlying nonsyndromic ARM is remarkably scarce. Most studies were focused on screening of candidate genes for mutations or single-nucleotide polymorphisms, which did not yield any substantial evidence. Nongenetic factors fairly consistently found to be associated with ARM are assisted reproductive techniques, multiple pregnancy, preterm delivery, low birth weight, maternal overweight or obesity, and preexisting diab...

European Journal of Pediatrics, 2014

Anorectal malformations (ARM) are rare congenital malformations of the gastrointestinal tract. Ap... more Anorectal malformations (ARM) are rare congenital malformations of the gastrointestinal tract. Approximately 60 % of the patients have additional congenital malformations, such as hypospadias. A recently published article showed that deletion of one single gene, dickkopf WNT signaling pathway inhibitor-1 (Dkk1), resulted in an imperforate anus with rectourinary fistula and preputial hypospadias in mice. To determine whether DKK1 also plays a role in the etiology of ARM and hypospadias in humans, we sequenced the four exons of the DKK1 gene in 17 patients affected with both ARM and hypospadias. No new potential disease-causing variant was identified. However, we detected a known non-synonymous variant in one patient, which was predicted in silico to be damaging, and the corresponding unaffected amino acid is highly conserved. Conclusion: In this human study, a potential interesting non-synonymous variant was found in the DKK1 gene. Whether this variant plays a contributory role in the genesis of ARM or hypospadias would require a much larger study.

although the majority displayed various degrees of developmental delay and speech disturbances. O... more although the majority displayed various degrees of developmental delay and speech disturbances. Other clinical features included behavioral problems, hypotonia, and dysmorphic facial features. Notably, none of the patients was diagnosed with a congenital heart defect. We found a high degree of inherited duplications. Additional copy number changes of unclear clinical significance were identified in 5 of our patients, and it is possible that these may contribute to the phenotypic expression in these patients as has been suggested recently in a 2-hit 'digenic' model for 16p12.1 deletions. The varied phenotypic expression and incomplete penetrance observed for distal 22q11.2 duplications makes it exceedingly difficult to ascribe pathogenicity for these duplications. Given the observed enrichment of the duplication in patient samples versus healthy controls, it is likely that distal 22q11.2 duplications represent a susceptibility/risk locus for speech and mild developmental delay.

Birth Defects Research Part A: Clinical and Molecular Teratology, 2014

Both genetic and nongenetic factors are suggested to be involved in the etiology of congenital an... more Both genetic and nongenetic factors are suggested to be involved in the etiology of congenital anorectal malformations (ARM). Maternal periconceptional use of folic acid supplements were inconsistently suggested to play a role in the prevention of ARM. Therefore, we investigated independent associations and interactions of maternal periconceptional folic acid supplement use and the infant and maternal MTHFR (methylenetetrahydrofolate reductase) C677T polymorphisms with the risk of ARM and subgroups of ARM. A case-control study was conducted among 371 nonsyndromic ARM cases and 714 population-based controls born between 1990 and 2012 using maternal questionnaires and DNA samples from mother and child. Cases were treated for ARM at departments of Pediatric Surgery of the Radboud university medical center, Sophia Children's Hospital-Erasmus MC Rotterdam, and the University Medical Center Groningen in The Netherlands and hospitals throughout Germany. No association with folic acid use was present (odds ratio = 1.1; 95% confidence interval: 0.8-1.4) for ARM as a group. Infant and maternal MTHFR C677T polymorphisms were weakly associated with isolated ARM in particular. Lack of folic acid supplement use in combination with infants or mothers carrying the MTHFR C677T polymorphism did not seem to increase the risk of ARM or subgroups of ARM. The relative excess risks due to interaction did not clearly indicate interaction on an additive scale either. This first study investigating interactions between periconceptional folic acid supplement use and infant and maternal MTHFR C677T polymorphisms in the etiology of ARM did not provide evidence for a role of this gene-environment interaction.

Pediatric Surgery International, 2010

Purpose The recently established International Consortium on Anorectal Malformations aims to iden... more Purpose The recently established International Consortium on Anorectal Malformations aims to identify genetic and environmental risk factors in the etiology of syndromic and nonsyndromic anorectal malformations (ARM) by promoting collaboration through data sharing and combined research activities.

Orphanet Journal of Rare Diseases, 2011

Background: The kyphoscoliotic type of Ehlers-Danlos syndrome (EDS VIA) (OMIM 225400) is a rare i... more Background: The kyphoscoliotic type of Ehlers-Danlos syndrome (EDS VIA) (OMIM 225400) is a rare inheritable connective tissue disorder characterized by a deficiency of collagen lysyl hydroxylase 1 (LH1; EC 1.14.11.4) due to mutations in PLOD1. Biochemically this results in underhydroxylation of collagen lysyl residues and, hence, an abnormal pattern of lysyl pyridinoline (LP) and hydroxylysyl pyridinoline (HP) crosslinks excreted in the urine. Clinically the disorder is characterized by hypotonia and kyphoscoliosis at birth, joint hypermobility, and skin hyperelasticity and fragility. Severe hypotonia usually leads to delay in gross motor development, whereas cognitive development is reported to be normal. Methods: We describe the clinical, biochemical and molecular characterisation, as well as electron microscopy findings of skin, in 15 patients newly diagnosed with this rare type of Ehlers-Danlos syndrome.

New England Journal of Medicine, 2013

Kidney International, 2013

Journal of Medical Genetics, 2008

Patients with a microscopically visible deletion of the distal part of the long arm of chromosome... more Patients with a microscopically visible deletion of the distal part of the long arm of chromosome 1 have a recognisable phenotype, including mental retardation, microcephaly, growth retardation, a distinct facial appearance and various midline defects including corpus callosum abnormalities, cardiac, gastro-oesophageal and urogenital defects, as well as various central nervous system anomalies. Patients with a submicroscopic, subtelomeric 1qter deletion have a similar phenotype, suggesting that the main phenotype of these patients is caused by haploinsufficiency of genes in this region. To describe the clinical presentation of 13 new patients with a submicroscopic deletion of 1q43q44, of which nine were interstitial, and to report on the molecular characterisation of the deletion size. The clinical presentation of these patients has clear similarities with previously reported cases with a terminal 1q deletion. Corpus callosum abnormalities were present in 10 of our patients. The AKT3 gene has been reported as an important candidate gene causing this abnormality. However, through detailed molecular analysis of the deletion sizes in our patient cohort, we were able to delineate the critical region for corpus callosum abnormalities to a 360 kb genomic segment which contains four possible candidate genes, but excluding the AKT3 gene.

Journal of Medical Genetics, 2009

Journal of Medical Genetics, 2010

Mutations in TRPV4, a gene that encodes a Ca(2+) permeable non-selective cation channel, have rec... more Mutations in TRPV4, a gene that encodes a Ca(2+) permeable non-selective cation channel, have recently been found in a spectrum of skeletal dysplasias that includes brachyolmia, spondylometaphyseal dysplasia, Kozlowski type (SMDK) and metatropic dysplasia (MD). Only a total of seven missense mutations were detected, however. The full spectrum of TRPV4 mutations and their phenotypes remained unclear. To examine TRPV4 mutation spectrum and phenotype-genotype association, we searched for TRPV4 mutations by PCR-direct sequencing from genomic DNA in 22 MD and 20 SMDK probands. TRPV4 mutations were found in all but one MD subject. In total, 19 different heterozygous mutations were identified in 41 subjects; two were recurrent and 17 were novel. In MD, a recurrent P799L mutation was identified in nine subjects, as well as 10 novel mutations including F471del, the first deletion mutation of TRPV4. In SMDK, a recurrent R594H mutation was identified in 12 subjects and seven novel mutations. An association between the position of mutations and the disease phenotype was also observed. Thus, P799 in exon 15 is a hot codon for MD mutations, as four different amino acid substitutions have been observed at this codon; while R594 in exon 11 is a hotspot for SMDK mutations. The TRPV4 mutation spectrum in MD and SMDK, which showed genotype-phenotype correlation and potential functional significance of mutations that are non-randomly distributed over the gene, was presented in this study. The results would help diagnostic laboratories establish efficient screening strategies for genetic diagnosis of the TRPV4 dysplasia family diseases.

Journal of Cellular and Molecular Medicine, 2009

Mutations in the LMNA gene [MIM 150330] cause a wide variety of inherited disorders called lamino... more Mutations in the LMNA gene [MIM 150330] cause a wide variety of inherited disorders called laminopathies that affect bone, fat, heart, nervous system, skeletal muscle and skin (reviewed in ). Lamins are intermediate filament proteins with N-and C-terminal regions flanking an ␣-helical rod domain. This structure

Human Mutation, 2013

The advent of massive parallel sequencing is rapidly changing the strategies employed for the gen... more The advent of massive parallel sequencing is rapidly changing the strategies employed for the genetic diagnosis and research of rare diseases that involve a large number of genes. So far it is not clear whether these approaches perform significantly better than conventional single gene testing as requested by clinicians. The current yield of this traditional diagnostic approach depends on a complex of factors that include gene-specific phenotype traits, and the relative frequency of the involvement of specific genes. To gauge the impact of the paradigm shift that is occurring in molecular diagnostics, we assessed traditional Sanger-based sequencing (in 2011) and exome sequencing followed by targeted bioinformatics analysis (in 2012) for five different conditions that are highly heterogeneous, and for which our center provides molecular diagnosis. We find that exome sequencing has a much higher diagnostic yield than Sanger sequencing for deafness, blindness, mitochondrial disease, and movement disorders. For microsatellite-stable colorectal cancer, this was low under both strategies. Even if all genes that could have been ordered by physicians had been tested, the larger number of genes captured by the exome would still have led to a clearly superior diagnostic yield at a fraction of the cost.

Human Mutation, 2008

Feingold syndrome (FS) is the most frequent cause of familial syndromic gastrointestinal atresia ... more Feingold syndrome (FS) is the most frequent cause of familial syndromic gastrointestinal atresia and follows autosomal dominant inheritance. FS is caused by germline mutations in or deletions of the MYCN gene. Previously, 12 different heterozygous MYCN mutations and two deletions containing multiple genes including MYCN were described. All these mutations result in haploinsufficiency of both the canonical MYCN protein and the shorter isoform, DMYCN. We report 11 novel mutations including seven mutations in exon 2 that result in a premature termination codon (PTC) in the long MYCN transcript. Moreover, we have identified a PTC in exon 1 that only affects the DMYCN isoform, without a phenotypic effect. This suggests that mutations in only DMYCN do not contribute to the FS. Additionally, we found three novel deletions encompassing MYCN. Together with our previous report we now have a total of four missense mutations in the DNA binding domain, 19 PTCs of which six render the transcript subject to nonsense-mediated decay (NMD), and five larger deletions in a total of 77 patients. We have reviewed the clinical features of these patients, and found that digital anomalies, e.g., brachymesophalangy and toe syndactyly, are the most consistent features, present in 100% and 97% of the patients, respectively. Small head circumference was present in 89% of the cases. Gastrointestinal atresia remains the most important major congenital anomaly (55%), but cardiac and renal anomalies are also frequent. We suggest that the presence of brachymesophalangy and toe syndactyly in combination with microcephaly is enough to justify MYCN analysis. Hum Mutat 29(9), 1125-1132, 2008. r r 2008 Wiley-Liss, Inc.