Publications by authors named "Tracy Lester"

24 Publications

  • Page 1 of 1

SMAD6 variants in craniosynostosis: genotype and phenotype evaluation.

Genet Med 2020 09 5;22(9):1498-1506. Epub 2020 Jun 5.

MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.

Purpose: Enrichment of heterozygous missense and truncating SMAD6 variants was previously reported in nonsyndromic sagittal and metopic synostosis, and interaction of SMAD6 variants with a common polymorphism nearBMP2 (rs1884302) was proposed to contribute to inconsistent penetrance. We determined the occurrence of SMAD6 variants in all types of craniosynostosis, evaluated the impact of different missense variants on SMAD6 function, and tested independently whether rs1884302 genotype significantly modifies the phenotype.

Methods: We performed resequencing of SMAD6 in 795 unsolved patients with any type of craniosynostosis and genotyped rs1884302 in SMAD6-positive individuals and relatives. We examined the inhibitory activity and stability of SMAD6 missense variants.

Results: We found 18 (2.3%) different rare damaging SMAD6 variants, with the highest prevalence in metopic synostosis (5.8%) and an 18.3-fold enrichment of loss-of-function variants comparedwith gnomAD data (P < 10). Combined with eight additional variants, ≥20/26 were transmitted from an unaffected parent but rs1884302 genotype did not predict phenotype.

Conclusion: Pathogenic SMAD6 variants substantially increase the risk of both nonsyndromic and syndromic presentations of craniosynostosis, especially metopic synostosis. Functional analysis is important to evaluate missense variants. Genotyping of rs1884302 is not clinically useful. Mechanisms to explain the remarkable diversity of phenotypes associated with SMAD6 variants remain obscure.
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http://dx.doi.org/10.1038/s41436-020-0817-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7462747PMC
September 2020

Implementation of a genomic medicine multi-disciplinary team approach for rare disease in the clinical setting: a prospective exome sequencing case series.

Genome Med 2019 07 25;11(1):46. Epub 2019 Jul 25.

National Institute for Health Research Biomedical Research Centre, Oxford, UK.

Background: A multi-disciplinary approach to promote engagement, inform decision-making and support clinicians and patients is increasingly advocated to realise the potential of genome-scale sequencing in the clinic for patient benefit. Here we describe the results of establishing a genomic medicine multi-disciplinary team (GM-MDT) for case selection, processing, interpretation and return of results.

Methods: We report a consecutive case series of 132 patients (involving 10 medical specialties with 43.2% cases having a neurological disorder) undergoing exome sequencing over a 10-month period following the establishment of the GM-MDT in a UK NHS tertiary referral hospital. The costs of running the MDT are also reported.

Results: In total 76 cases underwent exome sequencing following triage by the GM-MDT with a clinically reportable molecular diagnosis in 24 (31.6%). GM-MDT composition, operation and rationale for whether to proceed to sequencing are described, together with the health economics (cost per case for the GM-MDT was £399.61), the utility and informativeness of exome sequencing for molecular diagnosis in a range of traits, the impact of choice of sequencing strategy on molecular diagnostic rates and challenge of defining pathogenic variants. In 5 cases (6.6%), an alternative clinical diagnosis was indicated by sequencing results. Examples were also found where findings from initial genetic testing were reconsidered in the light of exome sequencing including TP63 and PRKAG2 (detection of a partial exon deletion and a mosaic missense pathogenic variant respectively); together with tissue-specific mosaicism involving a cytogenetic abnormality following a normal prenatal array comparative genomic hybridization.

Conclusions: This consecutive case series describes the results and experience of a multidisciplinary team format that was found to promote engagement across specialties and facilitate return of results to the responsible clinicians.
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http://dx.doi.org/10.1186/s13073-019-0651-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6659244PMC
July 2019

ERF-related craniosynostosis: The phenotypic and developmental profile of a new craniosynostosis syndrome.

Am J Med Genet A 2019 04 13;179(4):615-627. Epub 2019 Feb 13.

Clinical Genetics Service, Great Ormond Street Hospital, London, United Kingdom.

Mutations in the ERF gene, coding for ETS2 repressor factor, a member of the ETS family of transcription factors cause a recently recognized syndromic form of craniosynostosis (CRS4) with facial dysmorphism, Chiari-1 malformation, speech and language delay, and learning difficulties and/or behavioral problems. The overall prevalence of ERF mutations in patients with syndromic craniosynostosis is around 2%, and 0.7% in clinically nonsyndromic craniosynostosis. Here, we present findings from 16 unrelated probands with ERF-related craniosynostosis, with additional data from 20 family members sharing the mutations. Most of the probands exhibited multisutural (including pan-) synostosis but a pattern involving the sagittal and lambdoid sutures (Mercedes-Benz pattern) predominated. Importantly the craniosynostosis was often postnatal in onset, insidious and progressive with subtle effects on head morphology resulting in a median age at presentation of 42 months among the probands and, in some instances, permanent visual impairment due to unsuspected raised intracranial pressure (ICP). Facial dysmorphism (exhibited by all of the probands and many of the affected relatives) took the form of orbital hypertelorism, mild exorbitism and malar hypoplasia resembling Crouzon syndrome but, importantly, a Class I occlusal relationship. Speech delay, poor gross and/or fine motor control, hyperactivity and poor concentration were common. Cranial vault surgery for raised ICP and/or Chiari-1 malformation was expected when multisutural synostosis was observed. Variable expressivity and nonpenetrance among genetically affected relatives was encountered. These observations form the most complete phenotypic and developmental profile of this recently identified craniosynostosis syndrome yet described and have important implications for surgical intervention and follow-up.
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http://dx.doi.org/10.1002/ajmg.a.61073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491982PMC
April 2019

Prenatal exome sequencing analysis in fetal structural anomalies detected by ultrasonography (PAGE): a cohort study.

Lancet 2019 02 31;393(10173):747-757. Epub 2019 Jan 31.

Department of Clinical Genetics, St Michael's Hospital, University Hospitals Bristol, Bristol, UK.

Background: Fetal structural anomalies, which are detected by ultrasonography, have a range of genetic causes, including chromosomal aneuploidy, copy number variations (CNVs; which are detectable by chromosomal microarrays), and pathogenic sequence variants in developmental genes. Testing for aneuploidy and CNVs is routine during the investigation of fetal structural anomalies, but there is little information on the clinical usefulness of genome-wide next-generation sequencing in the prenatal setting. We therefore aimed to evaluate the proportion of fetuses with structural abnormalities that had identifiable variants in genes associated with developmental disorders when assessed with whole-exome sequencing (WES).

Methods: In this prospective cohort study, two groups in Birmingham and London recruited patients from 34 fetal medicine units in England and Scotland. We used whole-exome sequencing (WES) to evaluate the presence of genetic variants in developmental disorder genes (diagnostic genetic variants) in a cohort of fetuses with structural anomalies and samples from their parents, after exclusion of aneuploidy and large CNVs. Women were eligible for inclusion if they were undergoing invasive testing for identified nuchal translucency or structural anomalies in their fetus, as detected by ultrasound after 11 weeks of gestation. The partners of these women also had to consent to participate. Sequencing results were interpreted with a targeted virtual gene panel for developmental disorders that comprised 1628 genes. Genetic results related to fetal structural anomaly phenotypes were then validated and reported postnatally. The primary endpoint, which was assessed in all fetuses, was the detection of diagnostic genetic variants considered to have caused the fetal developmental anomaly.

Findings: The cohort was recruited between Oct 22, 2014, and June 29, 2017, and clinical data were collected until March 31, 2018. After exclusion of fetuses with aneuploidy and CNVs, 610 fetuses with structural anomalies and 1202 matched parental samples (analysed as 596 fetus-parental trios, including two sets of twins, and 14 fetus-parent dyads) were analysed by WES. After bioinformatic filtering and prioritisation according to allele frequency and effect on protein and inheritance pattern, 321 genetic variants (representing 255 potential diagnoses) were selected as potentially pathogenic genetic variants (diagnostic genetic variants), and these variants were reviewed by a multidisciplinary clinical review panel. A diagnostic genetic variant was identified in 52 (8·5%; 95% CI 6·4-11·0) of 610 fetuses assessed and an additional 24 (3·9%) fetuses had a variant of uncertain significance that had potential clinical usefulness. Detection of diagnostic genetic variants enabled us to distinguish between syndromic and non-syndromic fetal anomalies (eg, congenital heart disease only vs a syndrome with congenital heart disease and learning disability). Diagnostic genetic variants were present in 22 (15·4%) of 143 fetuses with multisystem anomalies (ie, more than one fetal structural anomaly), nine (11·1%) of 81 fetuses with cardiac anomalies, and ten (15·4%) of 65 fetuses with skeletal anomalies; these phenotypes were most commonly associated with diagnostic variants. However, diagnostic genetic variants were least common in fetuses with isolated increased nuchal translucency (≥4·0 mm) in the first trimester (in three [3·2%] of 93 fetuses).

Interpretation: WES facilitates genetic diagnosis of fetal structural anomalies, which enables more accurate predictions of fetal prognosis and risk of recurrence in future pregnancies. However, the overall detection of diagnostic genetic variants in a prospectively ascertained cohort with a broad range of fetal structural anomalies is lower than that suggested by previous smaller-scale studies of fewer phenotypes. WES improved the identification of genetic disorders in fetuses with structural abnormalities; however, before clinical implementation, careful consideration should be given to case selection to maximise clinical usefulness.

Funding: UK Department of Health and Social Care and The Wellcome Trust.
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http://dx.doi.org/10.1016/S0140-6736(18)31940-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6386638PMC
February 2019

A three-generation family with metaphyseal dysplasia, maxillary hypoplasia and brachydactyly (MDMHB) due to intragenic RUNX2 duplication.

Eur J Hum Genet 2018 09 11;26(9):1288-1293. Epub 2018 Jun 11.

North West Thames Regional Genetic Service, London North West Hospitals NHS Trust, Harrow, Middlesex, HA1 3UJ, UK.

Metaphyseal dysplasia with maxillary hypoplasia and brachydactyly (MDMHB) is an autosomal-dominant skeletal dysplasia characterised by metaphyseal flaring of the long bones, enlargement of the medial halves of the clavicles, maxillary hypoplasia, brachydactyly, dental anomalies and mild osteoporosis. To date, only one large French Canadian family and a Finnish woman have been reported with the condition. In both, intragenic duplication encompassing exons 3-5 of the RUNX2 gene was identified. We describe a new, three-generation family with clinical features of MDMHB and an intragenic tandem duplication of RUNX2 exons 3-6. Dental problems were the primary presenting feature in all four affected individuals. We compare the features in our family to those previously reported in MDMHB, review the natural history of this condition and highlight the importance of considering an underlying skeletal dysplasia in patients presenting with significant dental problems and other suggestive features, including disproportionate short stature and/or digital anomalies.
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http://dx.doi.org/10.1038/s41431-018-0166-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6117264PMC
September 2018

2 new cases of pontocerebellar hypoplasia type 10 identified by whole exome sequencing in a Turkish family.

Eur J Med Genet 2018 May 4;61(5):273-279. Epub 2018 Jan 4.

Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.

Pontocerebellar hypoplasia type 10 (PCH10) is a progressive autosomal recessive neurodegenerative disorder that has been recently described in association with cleavage and polyadenylation factor I subunit 1 (CLP1) mutations. To date, all reported cases have the same homozygous missense mutation in the CLP1 gene suggesting a founder mutation. CLP1 is an RNA kinase involved in tRNA splicing and maturation. There is evidence that the mutation is associated with functionally impaired kinase activity and subsequent defective tRNA processing. Through whole exome sequencing, we identified the same mutation in an extended family of Turkish origin. Both children presented with severe psychomotor delay, progressive microcephaly, and constipation. However, intrafamilial phenotypic variability is suggested due to the variability in their brain abnormalities and clinical features.
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http://dx.doi.org/10.1016/j.ejmg.2018.01.002DOI Listing
May 2018

Localized TWIST1 and TWIST2 basic domain substitutions cause four distinct human diseases that can be modeled in Caenorhabditis elegans.

Hum Mol Genet 2017 06;26(11):2118-2132

Department of Biology, The Catholic University of America, Washington, DC 20064, USA.

Twist transcription factors, members of the basic helix-loop-helix family, play crucial roles in mesoderm development in all animals. Humans have two paralogous genes, TWIST1 and TWIST2, and mutations in each gene have been identified in specific craniofacial disorders. Here, we describe a new clinical entity, Sweeney-Cox syndrome, associated with distinct de novo amino acid substitutions (p.Glu117Val and p.Glu117Gly) at a highly conserved glutamic acid residue located in the basic DNA binding domain of TWIST1, in two subjects with frontonasal dysplasia and additional malformations. Although about one hundred different TWIST1 mutations have been reported in patients with the dominant haploinsufficiency Saethre-Chotzen syndrome (typically associated with craniosynostosis), substitutions uniquely affecting the Glu117 codon were not observed previously. Recently, subjects with Barber-Say and Ablepharon-Macrostomia syndromes were found to harbor heterozygous missense substitutions in the paralogous glutamic acid residue in TWIST2 (p.Glu75Ala, p.Glu75Gln and p.Glu75Lys). To study systematically the effects of these substitutions in individual cells of the developing mesoderm, we engineered all five disease-associated alleles into the equivalent Glu29 residue encoded by hlh-8, the single Twist homolog present in Caenorhabditis elegans. This allelic series revealed that different substitutions exhibit graded severity, in terms of both gene expression and cellular phenotype, which we incorporate into a model explaining the various human disease phenotypes. The genetic analysis favors a predominantly dominant-negative mechanism for the action of amino acid substitutions at this highly conserved glutamic acid residue and illustrates the value of systematic mutagenesis of C. elegans for focused investigation of human disease processes.
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http://dx.doi.org/10.1093/hmg/ddx107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438873PMC
June 2017

Diagnostic value of exome and whole genome sequencing in craniosynostosis.

J Med Genet 2017 04 24;54(4):260-268. Epub 2016 Nov 24.

Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

Background: Craniosynostosis, the premature fusion of one or more cranial sutures, occurs in ∼1 in 2250 births, either in isolation or as part of a syndrome. Mutations in at least 57 genes have been associated with craniosynostosis, but only a minority of these are included in routine laboratory genetic testing.

Methods: We used exome or whole genome sequencing to seek a genetic cause in a cohort of 40 subjects with craniosynostosis, selected by clinical or molecular geneticists as being high-priority cases, and in whom prior clinically driven genetic testing had been negative.

Results: We identified likely associated mutations in 15 patients (37.5%), involving 14 different genes. All genes were mutated in single families, except for (two families). We classified the other positive diagnoses as follows: commonly mutated craniosynostosis genes with atypical presentation (, ); other core craniosynostosis genes (, ); genes for which mutations are only rarely associated with craniosynostosis (, , , ); and known disease genes for which a causal relationship with craniosynostosis is currently unknown (, ). In two further families, likely novel disease genes are currently undergoing functional validation. In 5 of the 15 positive cases, the (previously unanticipated) molecular diagnosis had immediate, actionable consequences for either genetic or medical management (mutations in , , , ).

Conclusions: This substantial genetic heterogeneity, and the multiple actionable mutations identified, emphasises the benefits of exome/whole genome sequencing to identify causal mutations in craniosynostosis cases for which routine clinical testing has yielded negative results.
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http://dx.doi.org/10.1136/jmedgenet-2016-104215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5366069PMC
April 2017

Variable phenotype and discrete alterations of immune phenotypes in CTP synthase 1 deficiency: Report of 2 siblings.

J Allergy Clin Immunol 2016 12 14;138(6):1722-1725.e6. Epub 2016 Jul 14.

Clinical Immunology Group, Oxford NIHR Biomedical Research Centre, United Kingdom.

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http://dx.doi.org/10.1016/j.jaci.2016.04.059DOI Listing
December 2016

Apparently synonymous substitutions in FGFR2 affect splicing and result in mild Crouzon syndrome.

BMC Med Genet 2014 Aug 31;15:95. Epub 2014 Aug 31.

Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Headington, Oxford OX3 9DS, UK.

Background: Mutations of fibroblast growth factor receptor 2 (FGFR2) account for a higher proportion of genetic cases of craniosynostosis than any other gene, and are associated with a wide spectrum of severity of clinical problems. Many of these mutations are highly recurrent and their associated features well documented. Crouzon syndrome is typically caused by heterozygous missense mutations in the third immunoglobulin domain of FGFR2.

Case Presentation: Here we describe two families, each segregating a different, previously unreported FGFR2 mutation of the same nucleotide, c.1083A>G and c.1083A>T, both of which encode an apparently synonymous change at the Pro361 codon. We provide experimental evidence that these mutations affect normal FGFR2 splicing and document the clinical consequences, which include a mild Crouzon syndrome phenotype and reduced penetrance of craniosynostosis.

Conclusions: These observations add to a growing list of FGFR2 mutations that affect splicing and provide important clinical information for genetic counselling of families affected by these specific mutations.
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http://dx.doi.org/10.1186/s12881-014-0095-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236556PMC
August 2014

The fibroblast growth factor receptor 2 p.Ala172Phe mutation in Pfeiffer syndrome--history repeating itself.

Am J Med Genet A 2013 May 26;161A(5):1158-63. Epub 2013 Mar 26.

Department of Plastic Surgery, John Radcliffe Hospital, Oxford, UK.

Pfeiffer syndrome is an autosomal dominant condition classically combining craniosynostosis with digital anomalies of the hands and feet. The majority of cases are caused by heterozygous mutations in the third immunoglobulin-like domain (IgIII) of FGFR2, whilst a small number of cases can be attributed to mutations outside this region of the protein. A mild form of Pfeiffer syndrome can rarely be caused by a specific mutation in FGFR1. We report on the clinical and genetic findings in a three generation British family with Pfeiffer syndrome caused by a heterozygous missense mutation, p.Ala172Phe, located in the IgII domain of FGFR2. This is the first reported case of this particular mutation since Pfeiffer's index case, originally described in a German family in 1964, on which basis the syndrome was eponymously named. Genetic analysis demonstrated the two families to be unrelated. Similarities in phenotypes between the two families are discussed. Independent genetic origins, but phenotypic similarities in the two families add to the evidence supporting the theory of selfish spermatogonial selective advantage for this rare gain-of-function FGFR2 mutation.
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http://dx.doi.org/10.1002/ajmg.a.35842DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3652025PMC
May 2013

Reduced dosage of ERF causes complex craniosynostosis in humans and mice and links ERK1/2 signaling to regulation of osteogenesis.

Nat Genet 2013 Mar 27;45(3):308-13. Epub 2013 Jan 27.

Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

The extracellular signal-related kinases 1 and 2 (ERK1/2) are key proteins mediating mitogen-activated protein kinase signaling downstream of RAS: phosphorylation of ERK1/2 leads to nuclear uptake and modulation of multiple targets. Here, we show that reduced dosage of ERF, which encodes an inhibitory ETS transcription factor directly bound by ERK1/2 (refs. 2,3,4,5,6,7), causes complex craniosynostosis (premature fusion of the cranial sutures) in humans and mice. Features of this newly recognized clinical disorder include multiple-suture synostosis, craniofacial dysmorphism, Chiari malformation and language delay. Mice with functional Erf levels reduced to ∼30% of normal exhibit postnatal multiple-suture synostosis; by contrast, embryonic calvarial development appears mildly delayed. Using chromatin immunoprecipitation in mouse embryonic fibroblasts and high-throughput sequencing, we find that ERF binds preferentially to elements away from promoters that contain RUNX or AP-1 motifs. This work identifies ERF as a novel regulator of osteogenic stimulation by RAS-ERK signaling, potentially by competing with activating ETS factors in multifactor transcriptional complexes.
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http://dx.doi.org/10.1038/ng.2539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683605PMC
March 2013

Pure de novo partial trisomy 6p in a girl with craniosynostosis.

Am J Med Genet A 2013 Feb 10;161A(2):343-51. Epub 2013 Jan 10.

Department of Genetics, Institute of Child Health, Athens, Greece.

Duplications of chromosome 6p are rarely reported. We present the case of a girl with a de novo trisomy 6p12.3-p21.1 who showed clinical features characteristic of this syndrome, notably facial anomalies, psychomotor delay, and recurrent respiratory tract infections. The most striking feature, however, was craniosynostosis, manifested by the premature fusion of the right coronal and sagittal sutures. A review of the literature revealed that the presence of abnormal fontanelles and sutures is relatively common among patients with proximal trisomy 6p. Exclusion of the most frequently occurring craniosynostosis mutations, as well as of further chromosomal anomalies in our case, suggest the presence of a gene regulating suture formation within this region. Based on recent findings, we hypothesize that the runt-related transcription factor 2 (RUNX2) may be a reasonable candidate gene for craniosynostosis in such patients.
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http://dx.doi.org/10.1002/ajmg.a.35727DOI Listing
February 2013

The spectrum of mutations that underlie the neuromuscular junction synaptopathy in DOK7 congenital myasthenic syndrome.

Hum Mol Genet 2012 Sep 1;21(17):3765-75. Epub 2012 Jun 1.

Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK.

Congenital myasthenic syndromes (CMS) are a group of inherited diseases that affect synaptic transmission at the neuromuscular junction and result in fatiguable muscle weakness. A subgroup of CMS patients have a recessively inherited limb-girdle pattern of weakness caused by mutations in DOK7. DOK7 encodes DOK7, an adaptor protein that is expressed in the skeletal muscle and heart and that is essential for the development and maintenance of the neuromuscular junction. We have screened the DOK7 gene for mutations by polymerase chain reaction amplification and bi-directional sequencing of exonic and promoter regions and performed acetylcholine receptor (AChR) clustering assays and used exon trapping to determine the pathogenicity of detected variants. Approximately 18% of genetically diagnosed CMSs in the UK have mutations in DOK7, with mutations in this gene identified in more than 60 kinships to date. Thirty-four different pathogenic mutations were identified as well as 27 variants likely to be non-pathogenic. An exon 7 frameshift duplication c.1124_1127dupTGCC is commonly found in at least one allele. We analyse the effect of the common frameshift c.1124_1127dupTGCC and show that 10/11 suspected missense mutations have a deleterious effect on AChR clustering. We identify for the first time homozygous or compound heterozygous mutations that are localized 5' to exon 7. In addition, three silent variants in the N-terminal half of DOK7 are predicted to alter the splicing of the DOK7 RNA transcript. The DOK7 gene is highly polymorphic, and within these many variants, we define a spectrum of mutations that can underlie DOK7 CMS that will inform in managing this disorder.
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http://dx.doi.org/10.1093/hmg/dds198DOI Listing
September 2012

Gross deletions in TCOF1 are a cause of Treacher-Collins-Franceschetti syndrome.

Eur J Hum Genet 2012 Jul 8;20(7):769-77. Epub 2012 Feb 8.

Clinical Molecular Genetics Laboratory, Churchill Hospital, Oxford, UK.

Treacher-Collins-Franceschetti syndrome (TCS) is an autosomal dominant craniofacial disorder characterised by midface hypoplasia, micrognathia, downslanting palpebral fissures, eyelid colobomata, and ear deformities that often lead to conductive deafness. A total of 182 patients with signs consistent with a diagnosis of TCS were screened by DNA sequence and dosage analysis of the TCOF1 gene. In all, 92 cases were found to have a pathogenic mutation by sequencing and 5 to have a partial gene deletion. A further case had a novel in-frame deletion in the alternatively spliced exon 6A of uncertain pathogenicity. The majority of the pathogenic sequence changes were found to predict premature protein termination, however, four novel missense changes in the LIS1 homology motif at the 5' end of the gene were identified. The partial gene deletions of different sizes represent ~5.2% of all the pathogenic TCOF1 mutations identified, indicating that gene rearrangements account for a significant proportion of TCS cases. This is the first report of gene rearrangements resulting in TCS. These findings expand the TCOF1 mutation spectrum indicating that dosage analysis should be performed together with sequence analysis, a strategy that is predicted to have a sensitivity of 71% for patients in whom TCS is strongly suspected.
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http://dx.doi.org/10.1038/ejhg.2012.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376267PMC
July 2012

Atypical Crouzon syndrome with a novel Cys62Arg mutation in FGFR2 presenting with sagittal synostosis.

Cleft Palate Craniofac J 2012 May 25;49(3):373-7. Epub 2011 Nov 25.

Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.

The management of a 1-year-old boy with Crouzonoid features is presented with a description of molecular genetic investigations that revealed a previously unreported mutation of the fibroblast growth factor receptor 2 (FGFR2) gene encoding the amino acid substitution p.Cys62Arg within the immunoglobin-like (IgI) domain. The patient presented in atypical fashion with severe sagittal synostosis but only mild exorbitism and hypertelorism. Owing to the progressively increasing size of the cranial occipital bullet, a total calvarial modeling procedure was performed at 8 months of age to correct the craniofacial deformity. Standard genetic testing of the major mutational "hotspots" associated with craniosynostosis was initially negative. However, further testing for atypical sites of mutation revealed a heterozygous nucleotide substitution (c.184T>C) in exon 3 of FGFR2. This mutation has not been previously reported and is only the second to be identified in the IgI domain; it was not present in either parent, indicating that it had arisen de novo. The child remains well 6 months postoperatively but will be monitored more closely compared with the usual protocol for nonsyndromic sagittal synostosis owing to the potential for increased risk of secondary complications. Key learning points from this case include the need for careful phenotypic evaluation of children presenting with apparently isolated sagittal synostosis and genetic testing for atypical mutations if the usual hotspots are negative.
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http://dx.doi.org/10.1597/11-185DOI Listing
May 2012

Duplication of the EFNB1 gene in familial hypertelorism: imbalance in ephrin-B1 expression and abnormal phenotypes in humans and mice.

Hum Mutat 2011 Aug 12;32(8):930-8. Epub 2011 Jul 12.

Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.

Familial hypertelorism, characterized by widely spaced eyes, classically shows autosomal dominant inheritance (Teebi type), but some pedigrees are compatible with X-linkage. No mechanism has been described previously, but clinical similarity has been noted to craniofrontonasal syndrome (CFNS), which is caused by mutations in the X-linked EFNB1 gene. Here we report a family in which females in three generations presented with hypertelorism, but lacked either craniosynostosis or a grooved nasal tip, excluding CFNS. DNA sequencing of EFNB1 was normal, but further analysis revealed a duplication of 937 kb including EFNB1 and two flanking genes: PJA1 and STARD8. We found that the X chromosome bearing the duplication produces ∼1.6-fold more EFNB1 transcript than the normal X chromosome and propose that, in the context of X-inactivation, this difference in expression level of EFNB1 results in abnormal cell sorting leading to hypertelorism. To support this hypothesis, we provide evidence from a mouse model carrying a targeted human EFNB1 cDNA, that abnormal cell sorting occurs in the cranial region. Hence, we propose that X-linked cases resembling Teebi hypertelorism may have a similar mechanism to CFNS, and that cellular mosaicism for different levels of ephrin-B1 (as well as simple presence/absence) leads to craniofacial abnormalities.
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http://dx.doi.org/10.1002/humu.21521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170877PMC
August 2011

Prevalence and complications of single-gene and chromosomal disorders in craniosynostosis.

Pediatrics 2010 Aug 19;126(2):e391-400. Epub 2010 Jul 19.

Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK.

Objectives: We describe the first cohort-based analysis of the impact of genetic disorders in craniosynostosis. We aimed to refine the understanding of prognoses and pathogenesis and to provide rational criteria for clinical genetic testing.

Methods: We undertook targeted molecular genetic and cytogenetic testing for 326 children who required surgery because of craniosynostosis, were born in 1993-2002, presented to a single craniofacial unit, and were monitored until the end of 2007.

Results: Eighty-four children (and 64 relatives) had pathologic genetic alterations (86% single-gene mutations and 14% chromosomal abnormalities). The FGFR3 P250R mutation was the single largest contributor (24%) to the genetic group. Genetic diagnoses accounted for 21% of all craniosynostosis cases and were associated with increased rates of many complications. Children with an initial clinical diagnosis of nonsyndromic craniosynostosis were more likely to have a causative mutation if the synostoses were unicoronal or bicoronal (10 of 48 cases) than if they were sagittal or metopic (0 of 55 cases; P = .0003). Repeat craniofacial surgery was required for 58% of children with single-gene mutations but only 17% of those with chromosomal abnormalities (P = .01).

Conclusions: Clinical genetic assessment is critical for the treatment of children with craniosynostosis. Genetic testing of nonsyndromic cases (at least for FGFR3 P250R and FGFR2 exons IIIa/c) should be targeted to patients with coronal or multisuture synostoses. Single-gene disorders that disrupt physiologic signaling in the cranial sutures often require reoperation, whereas chromosomal abnormalities follow a more-indolent course, which suggests a different, secondary origin of the associated craniosynostosis.
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http://dx.doi.org/10.1542/peds.2009-3491DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3535761PMC
August 2010

Germline and somatic mosaicism for FGFR2 mutation in the mother of a child with Crouzon syndrome: Implications for genetic testing in "paternal age-effect" syndromes.

Am J Med Genet A 2010 Aug;152A(8):2067-73

Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

Crouzon syndrome is a dominantly inherited disorder characterized by craniosynostosis and facial dysostosis, caused by mutations in the fibroblast growth factor receptor 2 (FGFR2) gene; it belongs to a class of disorders that mostly arise as de novo mutations and exhibit a near-exclusive paternal origin of mutation and elevated paternal age ("paternal age effect"). However, even if this is the major mode of origin of mutations in paternal age-effect disorders, germline mosaicism may also occur. Here we describe the first molecularly documented evidence of germline and somatic mosaicism for FGFR2 mutation, identified in the mother of a child with Crouzon syndrome caused by a heterozygous c.1007A>G (p.Asp336Gly) substitution. Levels of maternal somatic mosaicism for this mutation, estimated by pyrosequencing, ranged from 3.3% in hair roots to 14.1% in blood. Our observation underlines the importance of parental molecular testing for accurate genetic counseling of the risk of recurrence for Crouzon, and other paternal age-effect syndromes.
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http://dx.doi.org/10.1002/ajmg.a.33513DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2988406PMC
August 2010

Reoperation for intracranial hypertension in TWIST1-confirmed Saethre-Chotzen syndrome: a 15-year review.

Plast Reconstr Surg 2009 Jun;123(6):1801-1810

Oxford, United Kingdom From the Oxford Craniofacial Unit and the Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, and the Oxford Medical Genetics Laboratories, Churchill Hospital.

Background: Saethre-Chotzen syndrome is a syndromic craniosynostosis defined by a genetic mutation affecting the TWIST1 gene on chromosome 7p21. It is typically associated with unicoronal or bicoronal synostosis, eyelid ptosis, dysmorphic external ears, and other variable facial and limb abnormalities. Surgical management of the craniosynostosis addresses the calvarial deformity and may relieve or reduce the risk of intracranial hypertension. The aim of this study was to assess surgical intervention, with particular consideration of the reoperation rate for intracranial hypertension, in Saethre-Chotzen syndrome patients.

Methods: A retrospective case note analysis was performed on all patients with a confirmed TWIST1 gene abnormality who attended the Oxford Craniofacial Unit over a 15-year period. Each patient's mutation and clinical features were recorded. Surgical intervention and sequelae were examined in greater detail.

Results: Thirty-four patients with genetically confirmed Saethre-Chotzen syndrome were identified. All had craniosynostosis (bicoronal, 76 percent; unicoronal, 18 percent; bicoronal and sagittal, 6 percent), and the majority had eyelid ptosis, low frontal hairline, and external ear anomalies. Thirty-one patients had received surgical intervention. Nine of 26 patients (35 percent) with at least 12 months of follow-up after primary intervention and eight of 19 patients (42 percent) with at least 5 years of follow-up developed intracranial hypertension necessitating secondary calvarial surgery.

Conclusions: Despite standard surgical intervention, patients with Saethre-Chotzen syndrome have a high rate (35 to 42 percent) of recurrent intracranial hypertension necessitating further surgical expansion. All patients with either bicoronal synostosis or unicoronal synostosis with syndromic features should be screened for TWIST1 mutations, as this confers a greater risk than nonsyndromic synostosis of the same sutures. Regular follow-up throughout the childhood years is essential.
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http://dx.doi.org/10.1097/PRS.0b013e3181a3f391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2719244PMC
June 2009

Clinical dividends from the molecular genetic diagnosis of craniosynostosis.

Am J Med Genet A 2007 Aug;143A(16):1941-9

Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.

A dozen years have passed since the first genetic lesion was identified in a family with craniosynostosis, the premature fusion of the cranial sutures. Subsequently, mutations in the FGFR2, FGFR3, TWIST1, and EFNB1 genes have been shown to account for approximately 25% of craniosynostosis, whilst several additional genes make minor contributions. Using specific examples, we show how these discoveries have enabled refinement of information on diagnosis, recurrence risk, prognosis for mental development, and surgical planning. However, phenotypic variability can present a significant challenge to the clinical interpretation of molecular genetic tests. In particular, the difficulty of analyzing the complex interaction of genetic background and prenatal environment in determining clinical features, limits the value of identifying low penetrance mutations.
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http://dx.doi.org/10.1002/ajmg.a.31905DOI Listing
August 2007

Clinical dividends from the molecular genetic diagnosis of craniosynostosis.

Am J Med Genet A 2006 Dec;140(23):2631-9

Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.

A dozen years have passed since the first genetic lesion was identified in a family with craniosynostosis, the premature fusion of the cranial sutures. Subsequently, mutations in the FGFR2, FGFR3, TWIST1, and EFNB1 genes have been shown to account for approximately 25% of craniosynostosis, whilst several additional genes make minor contributions. Using specific examples, we show how these discoveries have enabled refinement of information on diagnosis, recurrence risk, prognosis for mental development, and surgical planning. However, phenotypic variability can present a significant challenge to the clinical interpretation of molecular genetic tests. In particular, the difficulty of analyzing the complex interaction of genetic background and prenatal environment in determining clinical features, limits the value of identifying low penetrance mutations.
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http://dx.doi.org/10.1002/ajmg.a.31366DOI Listing
December 2006