David Bunyan - Academia.edu (original) (raw)

Papers by David Bunyan

Research paper thumbnail of Hereditary desmoid disease due to a frameshift mutation at codon 1924 of the APC gene

The American Journal of Human Genetics

Desmoid tumors are slowly growing fibrous tumors highly resistant to therapy and often fatal. Her... more Desmoid tumors are slowly growing fibrous tumors highly resistant to therapy and often fatal. Here, we report hereditary desmoid disease (HDD), a novel autosomal dominant trait with 100% penetrance affecting a three-generation kindred. Desmoid tumors are usually a complication of familial adenomatous polyposis, a predisposition to the early development of premalignant adenomatous polyps in the colorectum due to chainterminating mutations of the APC gene. In general, one or more members in -10% of the FAP families manifest desmoid tumors. Affected individuals from the HDD kindred are characterized by multifocal fibromatosis of the paraspinal muscles, breast, occiput, arms, lower ribs, abdominal wall, and mesentery. Osteomas, epidermal cysts, and other congenital features were also observed. We show that HDD segregates with an unusual germline chain-terminating mutation at the 3' end of the APC gene (codon 1924) with somatic loss of the wild-type allele leading to tumor development.

Research paper thumbnail of A novel FOXP3 mutation causing fetal akinesia and recurrent male miscarriages

Clinical Immunology, 2015

ABSTRACT

Research paper thumbnail of Collagen ( COL4A ) mutations are the most frequent mutations underlying adult focal segmental glomerulosclerosis

Nephrology Dialysis Transplantation, 2015

Multiple genes underlying focal segmental glomerulosclerosis (FSGS) and/or steroid-resistant neph... more Multiple genes underlying focal segmental glomerulosclerosis (FSGS) and/or steroid-resistant nephrotic syndrome (SRNS) have been identified, with the recent inclusion of collagen IV mutations responsible for Alport disease (AD) or thin basement membrane nephropathy (TBMN). We aimed to investigate the distribution of gene mutations in adult patients with primary FSGS/SRNS by targeted next generation sequencing (NGS). Eighty-one adults from 76 families were recruited; 24 families had a history of renal disease. A targeted NGS panel was designed and applied, covering 39 genes implicated in FSGS/SRNS including COL4A3-5. Confirmed pathogenic mutations were found in 10 patients (6 with family history) from 9 families (diagnostic rate 12%). Probably pathogenic mutations were identified in an additional six patients (combined diagnostic rate 20%). Definitely pathogenic mutations were identified in 22% of patients with family history and 10% without. Mutations in COL4A3-5 were present in eight patients from six families, representing 56% of definitely pathogenic mutations, and establishing a diagnosis of AD in six patients and TBMN in two patients. Collagen mutations were identified in 38% of families with familial FSGS, and 3% with sporadic FSGS, with over half the mutations occurring in COL4A5. Patients with collagen mutations were younger at presentation and more likely to have family history, haematuria and glomerular basement membrane abnormalities. We show that collagen IV mutations, including COL4A5, frequently underlie FSGS and should be considered, particularly with a positive family history. Targeted NGS improves diagnostic efficiency by investigating many candidate genes in parallel.

Research paper thumbnail of Different denaturation rates between methylated and non-methylated genomic DNA can result in allele-specific PCR amplification

Open Journal of Genetics, 2011

We analysed a DNA sample from a father and child who were both heterozygous for a 7 base pair ins... more We analysed a DNA sample from a father and child who were both heterozygous for a 7 base pair insertion in the MEST gene differentially-methylated promoter region, previously shown by PCR analysis of bisulphite-treated DNA to be on the methylated allele in the unaffected father and the unmethylated allele in the affected child. PCR from genomic DNA was then carried out using a commercial PCR kit with its recommended initial DNA denaturation step of 2 minutes. Subsequent sequence analysis showed that only the non-methylated allele had been amplified, the father appearing to be homozygous normal and the child appearing to have a homozygous 7 b.p. insertion. The PCR protocol was then modified in order to use a longer DNA denaturation stage prior to the addition of the polymerase enzyme. Upon doing so, both the methylated and non-methylated alleles were then identifiable by sequencing with the mutation appearing in its expected heterozygous form. These results highlight the fact that the methylation status of DNA can affect the denaturation rate prior to PCR and result in allele drop-out, showing that the standard protocols of commercial kits should be used with caution when working with methylated regions of DNA.

Research paper thumbnail of Homozygosity for a novel deletion downstream of the SHOX gene provides evidence for an additional long range regulatory region with a mild phenotypic effect

American journal of medical genetics. Part A, 2014

Léri-Weill dyschondrosteosis is caused by heterozygous mutations in SHOX or its flanking sequence... more Léri-Weill dyschondrosteosis is caused by heterozygous mutations in SHOX or its flanking sequences, including whole or partial gene deletions, point mutations within the coding sequence, and deletions of downstream regulatory elements. The same mutations when biallelic cause the more severe Langer Mesomelic dysplasia. Here, we report on a consanguineous family with a novel deletion downstream of SHOX in which homozygously deleted individuals have a phenotype intermediate between Léri-Weill dyschondrosteosis and Langer Mesomelic dysplasia while heterozygously deleted individuals are mostly asymptomatic. The deleted region is distal to all previously described 3' deletions, suggesting the presence of an additional regulatory element, deletions of which have a milder, variable phenotypic effect.

Research paper thumbnail of X-Linked Dominant Congenital Ptosis Cosegregating with an Interstitial Insertion of a Chromosome 1p21.3 Fragment into a Quasipalindromic Sequence in Xq27.1

Open Journal of Genetics, 2014

Blepharoptosis (ptosis) is defined as the abnormal drooping of the upper eyelid and is a feature ... more Blepharoptosis (ptosis) is defined as the abnormal drooping of the upper eyelid and is a feature of many conditions. It can be in isolated or syndromic form, bilateral or unilateral and congenital or acquired. Previously we have carried out linkage analysis on a family with dominantly inherited congenital bilateral isolated ptosis and found the condition to be linked to a region of approximately 20 megabases of chromosome Xq24-Xq27.1 with a cumulative LOD score of 5.89. We now describe further analysis using array comparative genomic hybridisation (array CGH), fluorescence in situ hybridisation (FISH), long range PCR and sequencing. This has enabled us to identify and characterise at the level of DNA sequence an insertional duplication and rearrangement involving chromosomes 1p21.3 and a small quasipalindromic sequence in Xq27.1, disruption of which has been associated with other phenotypes but which is cosegregating with X-linked congenital bilateral isolated ptosis in this family. This work highlights the significance of the small quasipalindromic sequence in genomic rearrangements involving Xq27.1 and the importance of comprehensive molecular and molecular cytogenetic investigations to fully characterise genomic structural complexity.

Research paper thumbnail of PSEUDODOMINANT INHERITANCE OF SPASTIC ATAXIA OF CHARLEVOIX-SAGUENAY

Research paper thumbnail of Simultaneous MLPA-based multiplex point mutation and deletion analysis of the Dystrophin gene

Molecular Biotechnology, 2007

Research paper thumbnail of Risk of colorectal and endometrial cancers in EPCAM deletion-positive Lynch syndrome: a cohort study

The Lancet Oncology, 2011

Research paper thumbnail of Mutation Spectrum of Dystrophin Gene in Malaysian Patients with Duchenne/Becker Muscular Dystrophy

Journal of Neurogenetics, 2013

We undertook the clinical feature examination and dystrophin analysis using multiplex ligation-de... more We undertook the clinical feature examination and dystrophin analysis using multiplex ligation-dependent probe amplifi cation (MLPA) and direct DNA sequencing of selected exons in a cohort of 35 Malaysian Duchenne/Becker muscular dystrophy (DMD/BMD) patients. We found 27 patients with deletions of one or more exons, 2 patients with one exon duplication, 2 patients with nucleotide deletion, and 4 patients with nonsense mutations (including 1 patient with two nonsense mutations in the same exon). Although most cases showed compliance to the reading frame rule, we found two unrelated DMD patients with an in-frame deletion of the gene. Two novel mutations have been detected in the Dystrophin gene and our results were compatible with other studies where the majority of the mutations (62.8%) are located in the distal hotspot. However, the frequency of the mutations in our patient varied as compared with those found in other populations.

Research paper thumbnail of Cowden syndrome and Bannayan Riley Ruvalcaba syndrome represent one condition with variable expression and age-related penetrance: results of a clinical study of PTEN mutation carriers

Journal of Medical Genetics, 2007

Background: The most commonly reported phenotypes described in patients with PTEN mutations are B... more Background: The most commonly reported phenotypes described in patients with PTEN mutations are Bannayan-Riley-Ruvalcaba syndrome (BRRS), with childhood onset, macrocephaly, lipomas and developmental delay, and Cowden Syndrome (CS), an adult-onset condition recognised by mucocutaneous signs, with a risk of cancers, in particular those of the thyroid and breast. It has been suggested that BRRS and CS are the same condition, but the literature continues to separate them and seek a genotype-phenotype correlation.

Research paper thumbnail of Gross rearrangements of the MECP2 gene are found in both classical and atypical Rett syndrome patients

Journal of Medical Genetics, 2005

Research paper thumbnail of Clinical features in a family with an R460H mutation in transforming growth factor   receptor 2 gene

Journal of Medical Genetics, 2006

Objectives: To describe the clinical findings and natural history in 22 carriers of an R460H muta... more Objectives: To describe the clinical findings and natural history in 22 carriers of an R460H mutation in the transforming growth factor b receptor 2 gene (TGFbR2) from a five-generation kindred ascertained by familial aortic dissection. Methods: 13 of the confirmed carriers were interviewed and examined, and information about the remaining carrier was obtained from medical records. Clinical information about deceased individuals was obtained, when possible, from postmortem reports, death certificates and medical records. Results: There have been eight sudden deaths; the cause of death was aortic dissection in all six cases in which a postmortem examination was performed. Three individuals had undergone aortic replacement surgery. Dissection had occurred throughout the aorta, and in one case in the absence of aortic root dilatation. Subarachnoid haemorrhage, due to a ruptured berry aneurysm, had occurred in two individuals. Four gene carriers and one deceased family member who were investigated had tortuous cerebral blood vessels. One had tortuous vertebral arteries, two had tortuous carotid arteries and one a tortuous abdominal aorta. Two individuals were found to have a brachiocephalic artery aneurysm and a subclavian artery aneurysm, respectively. Conclusions: Despite the predisposition to aortic dilatation and dissection, individuals did not frequently manifest the skeletal features of Marfan syndrome, with the exception of joint hypermobility. No one individual had ocular lens dislocation. Striae and herniae were common. There was some overlap with Ehlers-Danlos syndrome type 4, OMIM 130050, with soft translucent skin, which is easily bruised. Other features were arthralgia, migraine and a tendency to fatigue easily, varicose veins and prominent skin striae. This family provides further evidence that mutations in TGFbR2 cause a distinct syndrome that needs to be distinguished from Marfan syndrome to direct investigation and management of patients and shows the natural history, spectrum of clinical features and variable penetrance of this newly recognised condition.

Research paper thumbnail of Novel heterozygous OTX2 mutations and whole gene deletions in anophthalmia, microphthalmia and coloboma

Human Mutation, 2008

Severe ocular malformations, including anophthalmia-microphthalmia (AM), are responsible for arou... more Severe ocular malformations, including anophthalmia-microphthalmia (AM), are responsible for around 25% of severe visual impairment in childhood. Recurrent interstitial deletions of 14q22-23 are associated with AM and a wide range of extra-ocular phenotypes including brain anomalies. The homeobox gene OTX2 is located at 14q22.3 and has recently been identified as mutated in AM patients. Eight human OTX2 mutations have been reported in subjects with severe eye malformations, including AM, and variable developmental delay. We screened a novel AM cohort for mutations and deletions in OTX2, and identified four new mutations in six individuals and two cases of whole gene deletions. Our data suggest that OTX2 mutations and deletions account for 2-3% of AM cases.

Research paper thumbnail of Germline and somatic mosaicism in a female carrier of Duchenne muscular dystrophy

Research paper thumbnail of Fluorescence in situ hybridisation studies provide evidence for somatic mosaicism in de novo dystrophin gene deletions

Human Genetics, 1995

The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect soma... more The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect somatic mosaicism in mothers of isolated deletion cases of Duchenne/ Becker muscular dystrophy. A control female with known germline and somatic mosaicism was examined, and both the normal cell line and the carrier cell line were detected. Subsequent FISH analysis of three other mothers of boys with apparent de novo dystrophin gene deletions revealed a second patient with a high level of somatic mosaicism, suggesting that a proportion of de novo dystrophin gene deletions occur as mitotic errors early in development rather than as meiotic errors during gametogenesis.

Research paper thumbnail of Epimutation of the TNDM locus and the Beckwith–Wiedemann syndrome centromeric locus in individuals with transient neonatal diabetes mellitus

Human Genetics, 2006

Transient neonatal diabetes mellitus (TNDM) is characterised by intra-uterine growth retardation,... more Transient neonatal diabetes mellitus (TNDM) is characterised by intra-uterine growth retardation, while Beckwith-Wiedemann syndrome (BWS) is a clinically heterogeneous overgrowth syndrome. Both TNDM and BWS may be caused by aberrant loss of methylation (LOM) at imprinted loci on chromosomes 6q24 and 11p15.5 respectively. Here we describe two patients with a clinical diagnosis of TNDM caused by LOM at the maternally methylated imprinted domain on 6q24; in addition, these patients had LOM at the centromeric differentially methylated region of 11p15.5. This shows that imprinting anomalies can affect more than one imprinted locus and may alter the clinical presentation of imprinted disease.

Research paper thumbnail of A small intraexonic deletion within the dystrophin gene suggests a possible mechanism of mutagenesis

Human Genetics, 1997

A case of Duchenne muscular dystrophy is described with an unusual mutation consisting of a 17-bp... more A case of Duchenne muscular dystrophy is described with an unusual mutation consisting of a 17-bp deletion within exon 47 of the dystrophin gene. The sequences on either side of the deletion have a high degree of intrastrand base complementarity. It is hypothesised that the mechanism generating the deletion may have been the formation of a hairpin loop structure in a single strand of DNA followed by enzymatic degradation at unpaired regions within the loop.

Research paper thumbnail of Exome analysis resolves differential diagnosis of familial kidney disease and uncovers a potential confounding variant

Research paper thumbnail of Prevalence of myocilin gene mutations in a novel UK cohort of POAG patients

Eye, 2010

Purpose To identify the prevalence of myocilin gene mutations in a UK glaucoma cohort. Methods Pr... more Purpose To identify the prevalence of myocilin gene mutations in a UK glaucoma cohort. Methods Primary open-angle (POAG) and normal tension glaucoma patients were recruited from the Southampton University Hospital Trust Eye Clinic and satellite regional glaucoma clinics. Phenotype data relating to disease history and other potential risk factors were recorded and blood samples collected for each consenting participant. Point mutation analysis of the myocilin gene was carried out using six overlapping PCR fragments covering the entire coding sequence of the gene. A total of 316 POAG samples were examined of which 7 (2.2 %) tested positive for disease-causing mutations in this gene. One of these seven non-synonymous mutations represented a previously unreported amino-acid substitution of cysteine for arginine at codon 296 (p.R296C) of the myocilin protein.

Research paper thumbnail of Hereditary desmoid disease due to a frameshift mutation at codon 1924 of the APC gene

The American Journal of Human Genetics

Desmoid tumors are slowly growing fibrous tumors highly resistant to therapy and often fatal. Her... more Desmoid tumors are slowly growing fibrous tumors highly resistant to therapy and often fatal. Here, we report hereditary desmoid disease (HDD), a novel autosomal dominant trait with 100% penetrance affecting a three-generation kindred. Desmoid tumors are usually a complication of familial adenomatous polyposis, a predisposition to the early development of premalignant adenomatous polyps in the colorectum due to chainterminating mutations of the APC gene. In general, one or more members in -10% of the FAP families manifest desmoid tumors. Affected individuals from the HDD kindred are characterized by multifocal fibromatosis of the paraspinal muscles, breast, occiput, arms, lower ribs, abdominal wall, and mesentery. Osteomas, epidermal cysts, and other congenital features were also observed. We show that HDD segregates with an unusual germline chain-terminating mutation at the 3' end of the APC gene (codon 1924) with somatic loss of the wild-type allele leading to tumor development.

Research paper thumbnail of A novel FOXP3 mutation causing fetal akinesia and recurrent male miscarriages

Clinical Immunology, 2015

ABSTRACT

Research paper thumbnail of Collagen ( COL4A ) mutations are the most frequent mutations underlying adult focal segmental glomerulosclerosis

Nephrology Dialysis Transplantation, 2015

Multiple genes underlying focal segmental glomerulosclerosis (FSGS) and/or steroid-resistant neph... more Multiple genes underlying focal segmental glomerulosclerosis (FSGS) and/or steroid-resistant nephrotic syndrome (SRNS) have been identified, with the recent inclusion of collagen IV mutations responsible for Alport disease (AD) or thin basement membrane nephropathy (TBMN). We aimed to investigate the distribution of gene mutations in adult patients with primary FSGS/SRNS by targeted next generation sequencing (NGS). Eighty-one adults from 76 families were recruited; 24 families had a history of renal disease. A targeted NGS panel was designed and applied, covering 39 genes implicated in FSGS/SRNS including COL4A3-5. Confirmed pathogenic mutations were found in 10 patients (6 with family history) from 9 families (diagnostic rate 12%). Probably pathogenic mutations were identified in an additional six patients (combined diagnostic rate 20%). Definitely pathogenic mutations were identified in 22% of patients with family history and 10% without. Mutations in COL4A3-5 were present in eight patients from six families, representing 56% of definitely pathogenic mutations, and establishing a diagnosis of AD in six patients and TBMN in two patients. Collagen mutations were identified in 38% of families with familial FSGS, and 3% with sporadic FSGS, with over half the mutations occurring in COL4A5. Patients with collagen mutations were younger at presentation and more likely to have family history, haematuria and glomerular basement membrane abnormalities. We show that collagen IV mutations, including COL4A5, frequently underlie FSGS and should be considered, particularly with a positive family history. Targeted NGS improves diagnostic efficiency by investigating many candidate genes in parallel.

Research paper thumbnail of Different denaturation rates between methylated and non-methylated genomic DNA can result in allele-specific PCR amplification

Open Journal of Genetics, 2011

We analysed a DNA sample from a father and child who were both heterozygous for a 7 base pair ins... more We analysed a DNA sample from a father and child who were both heterozygous for a 7 base pair insertion in the MEST gene differentially-methylated promoter region, previously shown by PCR analysis of bisulphite-treated DNA to be on the methylated allele in the unaffected father and the unmethylated allele in the affected child. PCR from genomic DNA was then carried out using a commercial PCR kit with its recommended initial DNA denaturation step of 2 minutes. Subsequent sequence analysis showed that only the non-methylated allele had been amplified, the father appearing to be homozygous normal and the child appearing to have a homozygous 7 b.p. insertion. The PCR protocol was then modified in order to use a longer DNA denaturation stage prior to the addition of the polymerase enzyme. Upon doing so, both the methylated and non-methylated alleles were then identifiable by sequencing with the mutation appearing in its expected heterozygous form. These results highlight the fact that the methylation status of DNA can affect the denaturation rate prior to PCR and result in allele drop-out, showing that the standard protocols of commercial kits should be used with caution when working with methylated regions of DNA.

Research paper thumbnail of Homozygosity for a novel deletion downstream of the SHOX gene provides evidence for an additional long range regulatory region with a mild phenotypic effect

American journal of medical genetics. Part A, 2014

Léri-Weill dyschondrosteosis is caused by heterozygous mutations in SHOX or its flanking sequence... more Léri-Weill dyschondrosteosis is caused by heterozygous mutations in SHOX or its flanking sequences, including whole or partial gene deletions, point mutations within the coding sequence, and deletions of downstream regulatory elements. The same mutations when biallelic cause the more severe Langer Mesomelic dysplasia. Here, we report on a consanguineous family with a novel deletion downstream of SHOX in which homozygously deleted individuals have a phenotype intermediate between Léri-Weill dyschondrosteosis and Langer Mesomelic dysplasia while heterozygously deleted individuals are mostly asymptomatic. The deleted region is distal to all previously described 3' deletions, suggesting the presence of an additional regulatory element, deletions of which have a milder, variable phenotypic effect.

Research paper thumbnail of X-Linked Dominant Congenital Ptosis Cosegregating with an Interstitial Insertion of a Chromosome 1p21.3 Fragment into a Quasipalindromic Sequence in Xq27.1

Open Journal of Genetics, 2014

Blepharoptosis (ptosis) is defined as the abnormal drooping of the upper eyelid and is a feature ... more Blepharoptosis (ptosis) is defined as the abnormal drooping of the upper eyelid and is a feature of many conditions. It can be in isolated or syndromic form, bilateral or unilateral and congenital or acquired. Previously we have carried out linkage analysis on a family with dominantly inherited congenital bilateral isolated ptosis and found the condition to be linked to a region of approximately 20 megabases of chromosome Xq24-Xq27.1 with a cumulative LOD score of 5.89. We now describe further analysis using array comparative genomic hybridisation (array CGH), fluorescence in situ hybridisation (FISH), long range PCR and sequencing. This has enabled us to identify and characterise at the level of DNA sequence an insertional duplication and rearrangement involving chromosomes 1p21.3 and a small quasipalindromic sequence in Xq27.1, disruption of which has been associated with other phenotypes but which is cosegregating with X-linked congenital bilateral isolated ptosis in this family. This work highlights the significance of the small quasipalindromic sequence in genomic rearrangements involving Xq27.1 and the importance of comprehensive molecular and molecular cytogenetic investigations to fully characterise genomic structural complexity.

Research paper thumbnail of PSEUDODOMINANT INHERITANCE OF SPASTIC ATAXIA OF CHARLEVOIX-SAGUENAY

Research paper thumbnail of Simultaneous MLPA-based multiplex point mutation and deletion analysis of the Dystrophin gene

Molecular Biotechnology, 2007

Research paper thumbnail of Risk of colorectal and endometrial cancers in EPCAM deletion-positive Lynch syndrome: a cohort study

The Lancet Oncology, 2011

Research paper thumbnail of Mutation Spectrum of Dystrophin Gene in Malaysian Patients with Duchenne/Becker Muscular Dystrophy

Journal of Neurogenetics, 2013

We undertook the clinical feature examination and dystrophin analysis using multiplex ligation-de... more We undertook the clinical feature examination and dystrophin analysis using multiplex ligation-dependent probe amplifi cation (MLPA) and direct DNA sequencing of selected exons in a cohort of 35 Malaysian Duchenne/Becker muscular dystrophy (DMD/BMD) patients. We found 27 patients with deletions of one or more exons, 2 patients with one exon duplication, 2 patients with nucleotide deletion, and 4 patients with nonsense mutations (including 1 patient with two nonsense mutations in the same exon). Although most cases showed compliance to the reading frame rule, we found two unrelated DMD patients with an in-frame deletion of the gene. Two novel mutations have been detected in the Dystrophin gene and our results were compatible with other studies where the majority of the mutations (62.8%) are located in the distal hotspot. However, the frequency of the mutations in our patient varied as compared with those found in other populations.

Research paper thumbnail of Cowden syndrome and Bannayan Riley Ruvalcaba syndrome represent one condition with variable expression and age-related penetrance: results of a clinical study of PTEN mutation carriers

Journal of Medical Genetics, 2007

Background: The most commonly reported phenotypes described in patients with PTEN mutations are B... more Background: The most commonly reported phenotypes described in patients with PTEN mutations are Bannayan-Riley-Ruvalcaba syndrome (BRRS), with childhood onset, macrocephaly, lipomas and developmental delay, and Cowden Syndrome (CS), an adult-onset condition recognised by mucocutaneous signs, with a risk of cancers, in particular those of the thyroid and breast. It has been suggested that BRRS and CS are the same condition, but the literature continues to separate them and seek a genotype-phenotype correlation.

Research paper thumbnail of Gross rearrangements of the MECP2 gene are found in both classical and atypical Rett syndrome patients

Journal of Medical Genetics, 2005

Research paper thumbnail of Clinical features in a family with an R460H mutation in transforming growth factor   receptor 2 gene

Journal of Medical Genetics, 2006

Objectives: To describe the clinical findings and natural history in 22 carriers of an R460H muta... more Objectives: To describe the clinical findings and natural history in 22 carriers of an R460H mutation in the transforming growth factor b receptor 2 gene (TGFbR2) from a five-generation kindred ascertained by familial aortic dissection. Methods: 13 of the confirmed carriers were interviewed and examined, and information about the remaining carrier was obtained from medical records. Clinical information about deceased individuals was obtained, when possible, from postmortem reports, death certificates and medical records. Results: There have been eight sudden deaths; the cause of death was aortic dissection in all six cases in which a postmortem examination was performed. Three individuals had undergone aortic replacement surgery. Dissection had occurred throughout the aorta, and in one case in the absence of aortic root dilatation. Subarachnoid haemorrhage, due to a ruptured berry aneurysm, had occurred in two individuals. Four gene carriers and one deceased family member who were investigated had tortuous cerebral blood vessels. One had tortuous vertebral arteries, two had tortuous carotid arteries and one a tortuous abdominal aorta. Two individuals were found to have a brachiocephalic artery aneurysm and a subclavian artery aneurysm, respectively. Conclusions: Despite the predisposition to aortic dilatation and dissection, individuals did not frequently manifest the skeletal features of Marfan syndrome, with the exception of joint hypermobility. No one individual had ocular lens dislocation. Striae and herniae were common. There was some overlap with Ehlers-Danlos syndrome type 4, OMIM 130050, with soft translucent skin, which is easily bruised. Other features were arthralgia, migraine and a tendency to fatigue easily, varicose veins and prominent skin striae. This family provides further evidence that mutations in TGFbR2 cause a distinct syndrome that needs to be distinguished from Marfan syndrome to direct investigation and management of patients and shows the natural history, spectrum of clinical features and variable penetrance of this newly recognised condition.

Research paper thumbnail of Novel heterozygous OTX2 mutations and whole gene deletions in anophthalmia, microphthalmia and coloboma

Human Mutation, 2008

Severe ocular malformations, including anophthalmia-microphthalmia (AM), are responsible for arou... more Severe ocular malformations, including anophthalmia-microphthalmia (AM), are responsible for around 25% of severe visual impairment in childhood. Recurrent interstitial deletions of 14q22-23 are associated with AM and a wide range of extra-ocular phenotypes including brain anomalies. The homeobox gene OTX2 is located at 14q22.3 and has recently been identified as mutated in AM patients. Eight human OTX2 mutations have been reported in subjects with severe eye malformations, including AM, and variable developmental delay. We screened a novel AM cohort for mutations and deletions in OTX2, and identified four new mutations in six individuals and two cases of whole gene deletions. Our data suggest that OTX2 mutations and deletions account for 2-3% of AM cases.

Research paper thumbnail of Germline and somatic mosaicism in a female carrier of Duchenne muscular dystrophy

Research paper thumbnail of Fluorescence in situ hybridisation studies provide evidence for somatic mosaicism in de novo dystrophin gene deletions

Human Genetics, 1995

The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect soma... more The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect somatic mosaicism in mothers of isolated deletion cases of Duchenne/ Becker muscular dystrophy. A control female with known germline and somatic mosaicism was examined, and both the normal cell line and the carrier cell line were detected. Subsequent FISH analysis of three other mothers of boys with apparent de novo dystrophin gene deletions revealed a second patient with a high level of somatic mosaicism, suggesting that a proportion of de novo dystrophin gene deletions occur as mitotic errors early in development rather than as meiotic errors during gametogenesis.

Research paper thumbnail of Epimutation of the TNDM locus and the Beckwith–Wiedemann syndrome centromeric locus in individuals with transient neonatal diabetes mellitus

Human Genetics, 2006

Transient neonatal diabetes mellitus (TNDM) is characterised by intra-uterine growth retardation,... more Transient neonatal diabetes mellitus (TNDM) is characterised by intra-uterine growth retardation, while Beckwith-Wiedemann syndrome (BWS) is a clinically heterogeneous overgrowth syndrome. Both TNDM and BWS may be caused by aberrant loss of methylation (LOM) at imprinted loci on chromosomes 6q24 and 11p15.5 respectively. Here we describe two patients with a clinical diagnosis of TNDM caused by LOM at the maternally methylated imprinted domain on 6q24; in addition, these patients had LOM at the centromeric differentially methylated region of 11p15.5. This shows that imprinting anomalies can affect more than one imprinted locus and may alter the clinical presentation of imprinted disease.

Research paper thumbnail of A small intraexonic deletion within the dystrophin gene suggests a possible mechanism of mutagenesis

Human Genetics, 1997

A case of Duchenne muscular dystrophy is described with an unusual mutation consisting of a 17-bp... more A case of Duchenne muscular dystrophy is described with an unusual mutation consisting of a 17-bp deletion within exon 47 of the dystrophin gene. The sequences on either side of the deletion have a high degree of intrastrand base complementarity. It is hypothesised that the mechanism generating the deletion may have been the formation of a hairpin loop structure in a single strand of DNA followed by enzymatic degradation at unpaired regions within the loop.

Research paper thumbnail of Exome analysis resolves differential diagnosis of familial kidney disease and uncovers a potential confounding variant

Research paper thumbnail of Prevalence of myocilin gene mutations in a novel UK cohort of POAG patients

Eye, 2010

Purpose To identify the prevalence of myocilin gene mutations in a UK glaucoma cohort. Methods Pr... more Purpose To identify the prevalence of myocilin gene mutations in a UK glaucoma cohort. Methods Primary open-angle (POAG) and normal tension glaucoma patients were recruited from the Southampton University Hospital Trust Eye Clinic and satellite regional glaucoma clinics. Phenotype data relating to disease history and other potential risk factors were recorded and blood samples collected for each consenting participant. Point mutation analysis of the myocilin gene was carried out using six overlapping PCR fragments covering the entire coding sequence of the gene. A total of 316 POAG samples were examined of which 7 (2.2 %) tested positive for disease-causing mutations in this gene. One of these seven non-synonymous mutations represented a previously unreported amino-acid substitution of cysteine for arginine at codon 296 (p.R296C) of the myocilin protein.