Split-hand/foot malformation 3 resulting from microduplications in 10q24 region in five patients from India

Split-hand/foot malformation (SHFM) is a genetically heterogeneous congenital limb reduction defect characterized by the deficiencies of central rays of the autopod. Tandem duplications at 10q24 locus account for approximately 20% of all SHFM cases. Here, we report five affected individuals from four unrelated Indian families with SHFM3 caused by microduplication of 10q24 locus showing varied clinical presentations. This report substantiates and extends the current understanding of this rare, multifaceted, and complex condition.

"Laurin-Sandrow Syndrome - a review of the literature and classification system"

INTRODUCTION

Laurin-Sandrow syndrome also known as tetramelic mirror-image polydactyly is a rare congenital disorder characterized classically by polysyndactyly of the hands, mirror feet and nose anomalies (hypoplasia of the nasal alae and short columella) often associated with ulnar and/or fibular duplication. As a pathologic entity, it is heterogeneous, the patients displaying a variety of symptoms. This review aims to analyze the different aspects of the condition, such as clinical findings and methods of treatment to summarize the principal features of Laurin-Sandrow syndrome.

MATERIALS AND METHODS

The review is based on searches on PubMed, Web of Science and Researchgate of the following terms: "Laurin-Sandrow syndrome", "mirror hands", "mirror feet", "tetramelic mirror-image polydactyly", "fibular dimelia" and "ulnar dimelia". Clinical cases, reviews and original articles were included.

RESULTS

As a consequence of our findings, we suggest a modification of the Al-Qattan classification system for Mirror Hand-Multiple Hand Spectrum.

CONCLUSION

Even though it has an extremely low incidence, a thorough understanding of the syndrome enables the surgeon to choose the appropriate treatment with the ultimate goal to improve the patient's life quality.

[Genetic analysis of a Chinese pedigree affected with congenital split-hand/foot malformation]

OBJECTIVE

To analyze the molecular genetics of a Chinese pedigree with congenital hand foot cleft.

METHODS

Single nucleotide polymorphism microarray (SNP array) was used to analyze the whole genome copy number variation.

RESULTS

SNP array analysis showed that there was a 433 kb repeat in 10q24.31-10q24.32 region, which contained LBX1, BTRC, POLL, OPCD and FBXW4 genes.

CONCLUSION

Microduplication of chromosome 10q24.31-10q24.32 may be the cause of congenital hand foot cleft in this pedigree.

Deletion of CTCF sites in the SHH locus alters enhancer-promoter interactions and leads to acheiropodia

Acheiropodia, congenital limb truncation, is associated with homozygous deletions in the LMBR1 gene around ZRS, an enhancer regulating SHH during limb development. How these deletions lead to this phenotype is unknown. Using whole-genome sequencing, we fine-mapped the acheiropodia-associated region to 12 kb and show that it does not function as an enhancer. CTCF and RAD21 ChIP-seq together with 4C-seq and DNA FISH identify three CTCF sites within the acheiropodia-deleted region that mediate the interaction between the ZRS and the SHH promoter. This interaction is substituted with other CTCF sites centromeric to the ZRS in the disease state. Mouse knockouts of the orthologous 12 kb sequence have no apparent abnormalities, showcasing the challenges in modelling CTCF alterations in animal models due to inherent motif differences between species. Our results show that alterations in CTCF motifs can lead to a Mendelian condition due to altered enhancer-promoter interactions.

Calmodulin Directly Interacts with the Cx43 Carboxyl-Terminus and Cytoplasmic Loop Containing Three ODDD-Linked Mutants (M147T, R148Q, and T154A) that Retain α-Helical Structure, but Exhibit Loss-of-Function and Cellular Trafficking Defects

The autosomal-dominant pleiotropic disorder called oculodentodigital dysplasia (ODDD) is caused by mutations in the gap junction protein Cx43. Of the 73 mutations identified to date, over one-third are localized in the cytoplasmic loop (Cx43CL) domain. Here, we determined the mechanism by which three ODDD mutations (M147T, R148Q, and T154A), all of which localize within the predicted 1-5-10 calmodulin-binding motif of the Cx43CL, manifest the disease. Nuclear magnetic resonance (NMR) and circular dichroism revealed that the three ODDD mutations had little-to-no effect on the ability of the Cx43CL to form α-helical structure as well as bind calmodulin. Combination of microscopy and a dye-transfer assay uncovered these mutations increased the intracellular level of Cx43 and those that trafficked to the plasma membrane did not form functional channels. NMR also identify that CaM can directly interact with the Cx43CT domain. The Cx43CT residues involved in the CaM interaction overlap with tyrosines phosphorylated by Pyk2 and Src. In vitro and in cyto data provide evidence that the importance of the CaM interaction with the Cx43CT may lie in restricting Pyk2 and Src phosphorylation, and their subsequent downstream effects.

Two novel GJA1 variants in oculodentodigital dysplasia

Background

Oculodentodigital dysplasia (ODDD) is a rare disorder with pleiotropic effects involving multiple body systems, caused by mutations in the gap junction protein alpha 1 (GJA1) gene. GJA1 gene encodes a polytopic connexin membrane protein, Cx43, that is a component of connexon membrane channels.

Methods

We describe two unrelated female probands referred for a genetic review in view of a dysmorphic clinical phenotype.

Results

Two novel missense mutations in GJA1 that substitute conserved amino acids in the first and second transmembrane domains (NM_000165.5: c.77T>C p.Leu26Pro and NM_000165.5:c.287T>G p.Val96Gly) were detected through targeted sequencing of GJA1. These variants were detected in the heterozygous state in the two Maltese probands and segregated with the disease phenotype.

Conclusion

This report further expands the mutational spectrum of ODDD.

New insights into DNA methylation signatures: SMARCA2 variants in Nicolaides-Baraitser syndrome

BACKGROUND

Nicolaides-Baraitser syndrome (NCBRS) is a neurodevelopmental disorder caused by pathogenic sequence variants in SMARCA2 which encodes the catalytic component of the chromatin remodeling BAF complex. Pathogenic variants in genes that encode epigenetic regulators have been associated with genome-wide changes in DNA methylation (DNAm) in affected individuals termed DNAm signatures.

METHODS

Genome-wide DNAm was assessed in whole-blood samples from the individuals with pathogenic SMARCA2 variants and NCBRS diagnosis (n = 8) compared to neurotypical controls (n = 23) using the Illumina MethylationEPIC array. Differential methylated CpGs between groups (DNAm signature) were identified and used to generate a model enabling classification variants of uncertain significance (VUS; n = 9) in SMARCA2 as "pathogenic" or "benign". A validation cohort of NCBRS cases (n = 8) and controls (n = 96) demonstrated 100% model sensitivity and specificity.

RESULTS

We identified a DNAm signature of 429 differentially methylated CpG sites in individuals with NCBRS. The genes to which these CpG sites map are involved in cell differentiation, calcium signaling, and neuronal function consistent with NCBRS pathophysiology. DNAm model classifications of VUS were concordant with the clinical phenotype; those within the SMARCA2 ATPase/helicase domain classified as "pathogenic". A patient with a mild neurodevelopmental NCBRS phenotype and a VUS distal to the ATPase/helicase domain did not score as pathogenic, clustering away from cases and controls. She demonstrated an intermediate DNAm profile consisting of one subset of signature CpGs with methylation levels characteristic of controls and another characteristic of NCBRS cases; each mapped to genes with ontologies consistent with the patient's unique clinical presentation.

CONCLUSIONS

Here we find that a DNAm signature of SMARCA2 pathogenic variants in NCBRS maps to CpGs relevant to disorder pathophysiology, classifies VUS, and is sensitive to the position of the variant in SMARCA2. The patient with an intermediate model score demonstrating a unique genotype-epigenotype-phenotype correlation underscores the potential utility of this signature as a functionally relevant VUS classification system scalable beyond binary "benign" versus "pathogenic" scoring. This is a novel feature of DNAm signatures that could enable phenotypic predictions from genotype data. Our findings also demonstrate that DNAm signatures can be domain-specific, highlighting the precision with which they can reflect genotypic variation.

GJA1 Variants Cause Spastic Paraplegia Associated with Cerebral Hypomyelination

Oculodentodigital dysplasia is an autosomal dominant disorder due to GJA1 variants characterized by dysmorphic features. Neurologic symptoms have been described in some patients but without a clear neuroimaging pattern. To understand the pathophysiology underlying neurologic deficits in oculodentodigital dysplasia, we studied 8 consecutive patients presenting with hereditary spastic paraplegia due to GJA1 variants. Clinical disease severity was highly variable. Cerebral MR imaging revealed variable white matter abnormalities, consistent with a hypomyelination pattern, and bilateral hypointense signal of the basal ganglia on T2-weighted images and/or magnetic susceptibility sequences, as seen in neurodegeneration with brain iron accumulation diseases. Patients with the more prominent basal ganglia abnormalities were the most disabled ones. This study suggests that GJA1-related hereditary spastic paraplegia is a complex neurodegenerative disease affecting both the myelin and the basal ganglia. GJA1 variants should be considered in patients with hereditary spastic paraplegia presenting with brain hypomyelination, especially if associated with neurodegeneration and a brain iron accumulation pattern.

Oculodentodigital Dysplasia with a Novel Mutation in GJA1 Diagnosed by Targeted Gene Panel Sequencing: A Case Report and Literature Review

Oculodentodigital dysplasia (ODDD; MIM #164200), a rare genetic disorder characterized by abnormal craniofacial, dental, ocular, and digital features, is caused by mutations in the gap junction alpha-1 (GJA1) gene. We report a case of a 6-year-old male who presented with dysmorphic facial features (short palpebral fissure, thin nose with hypoplastic alae nasi, and flat face), bilateral syndactyly, abnormal dentition, and proportionate short stature with growth hormone deficiency. A novel de novo heterozygous missense mutation (c.221A>C, p.H74P) in GJA1 was identified by targeted gene panel sequencing. This is the first case report of a novel ODDD-causing mutation in GJA1 confirmed by genetic analysis in Korea.

Novel mutations in HINT1 gene cause the autosomal recessive axonal neuropathy with neuromyotonia

Autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) is a rare form of hereditary neuropathy. Mutations in HINT1 gene have been identified to be the cause of this disorder. We report two unrelated patients who presented gait impairment, progressive distal muscle weakness and atrophy, neuromyotonia and foot deformities. Electrophysiological studies showed axonal motor neuropathy and neuromyotonic discharges. Using Next-generation sequencing, we identified two homozygous mutations, NM_005340.6: c.112T > C; p.(Cys38Arg) and NM_005340.6: c.289G > A; p.(Val97Met) in HINT1 gene. Based on the clinical presentation and molecular genetic analyses, ARAN-NM was diagnosed in both patients and NM_005340.6: c.112T > C; p.(Cys38Arg) and NM_005340.6: c.289G > A; p.(Val97Met) in HINT1 gene were believe to be causative for the disorder.

Autosomal Recessive Oculodentodigital Dysplasia: A Case Report and Review of the Literature

Oculodentodigital dysplasia (ODDD) is a rare condition characterized by a typical facial appearance and variable findings of the eyes, teeth, and fingers. ODDD is caused by mutations in the GJA1 gene in chromosome 6q22 and inherited in an autosomal dominant manner in the majority of the patients. However, in recent clinical reports, autosomal recessive ODDD cases due to by GJA1 mutations were also described. Here, we report on a 14-year-old boy with microphthalmia, microcornea, narrow nasal bridge, hypoplastic alae nasi, prominent columnella, hypodontia, dental caries, and partial syndactyly of the 2nd and 3rd toes. These clinical findings were concordant with the diagnosis of ODDD, and a novel homozygous mutation (c.442C>T, p.Arg148Ter) was determined in the GJA1 gene leading to a premature stop codon. His phenotypically normal parents were found to be carriers of the same mutation. This is the third family in the literature in which ODDD segregates in an autosomal recessive manner.

Autosomal dominant stapes fixation, syndactyly, and symphalangism in a family with NOG mutation: Long term follow-up on surgical treatment

OBJECTIVE

Evaluation of clinical findings and audiological outcome after surgery in a Danish family with autosomal dominant facio-audio-symphalangism syndrome with stapes fixation, syndactyly and symphalangism.

METHODS

Retrospective report on eight affected family members in a Danish family. Clinical investigation included X-ray, audiology and in one case video-recorded surgery. Main outcome measure was audiologic results after stapedectomy. Sanger DNA sequencing of NOG was performed on peripheral blood.

RESULTS

Audiologic analysis showed that seven of eight affected family members had bilateral conductive hearing loss. Three patients were treated with stapedectomy, on one or both ears, due to fixation of stapes. All the affected members had syndactyly and symphalangism. A not previously reported mutation in the NOG gene (c.688_699del, p.Cys230_Cys232delins11) was found to segregate with the stapes fixation, syndactyly, and symphalangism. p.Cys230_Cysdelins11 was classified as likely pathogenic according to guidelines from the American College of Medical Genetics and Genomics.

CONCLUSION

The clinical presentation of the reported mutation corresponds with previous case reports of families with NOG mutation. In this family, surgery with stapedectomy had lasting effect without renewed fixation of the stapes in a follow up period of 18 months-38 years.

[A phenotypic description of 26 patients with Ritscher-Schinzel syndrome (cranio-cerebello-cardiac dysplasia or 3C syndrome)]

INTRODUCTION

Ritscher-Schinzel syndrome (also known as cranio-cerebello-cardiac dysplasia or 3C syndrome) is a rare genetic syndrome that is mainly characterised by the association of cardiac and craniofacial anomalies together with others affecting the posterior fossa.

PATIENTS AND METHODS

We report on 26 patients with Ritscher-Schinzel syndrome at a hospital in Medellin, in the Department of Antioquia, Colombia.

RESULTS

Males account for 69% of this cohort. The mean age of the cohort was 30 months, and 42% were under the age of one year at the time of diagnosis. All of them presented ocular disorders, and megalocornea was the most frequent ocular manifestation (69%), whereas low-set ears (80.7%) and septal heart defects (68.7%) were the most common facial and cardiac malformations, respectively. The most frequent malformations of the posterior fossa were megacisterna magna (31.8%) and Dandy-Walker malformation (27%). 84% of the cases had delayed neurodevelopment or intellectual disability. Skeletal manifestations were frequent: the group consisting of camptodactyly, single palmar crease, overlapping fingers, vertical talus and nail hypoplasia were found in hands and feet in 96% of the cases.

CONCLUSIONS

Ritscher-Schinzel syndrome is a heterogeneous syndrome from the genetic and clinical point of view. These results suggest that the skeletal and ocular abnormalities that were observed can facilitate the phenotypic diagnosis. However, it is necessary to conduct further studies that allow us to gain a deeper knowledge of its prevalence and help identify other genes involved in this syndrome.

Oculo-Dento-Digital Dysplasia (ODDD) Due to a GJA1 Mutation: Report of a Case with Emphasis on Dental Manifestations

Oculo-dento-digital dysplasia (ODDD) is a congenital disorder manifesting with multiple phenotypic abnormalities involving the face, eyes, teeth, and limbs in addition to neurologic symptomatology. This report aims to present a female patient with ODDD who was referred due to extensive oral restorative needs. The presence of hypoplastic enamel triggered further evaluation. Characteristic facies with hypoplastic alae nasi and syndactyly offered greater insight into the phenotype of the syndrome. Clinical suspicion was confirmed by genetic sequencing revealing heterozygous mutation in GJA1. It is important to be aware of genetic disorders associated with characteristic dental malformations to offer appropriate counseling and treatment.

A Chromosome 7 Pericentric Inversion Defined at Single-Nucleotide Resolution Using Diagnostic Whole Genome Sequencing in a Patient with Hand-Foot-Genital Syndrome

Next generation sequencing methodologies are facilitating the rapid characterisation of novel structural variants at nucleotide resolution. These approaches are particularly applicable to variants initially identified using alternative molecular methods. We report a child born with bilateral postaxial syndactyly of the feet and bilateral fifth finger clinodactyly. This was presumed to be an autosomal recessive syndrome, due to the family history of consanguinity. Karyotype analysis revealed a homozygous pericentric inversion of chromosome 7 (46,XX,inv(7)(p15q21)x2) which was confirmed to be heterozygous in both unaffected parents. Since the resolution of the karyotype was insufficient to identify any putatively causative gene, we undertook medium-coverage whole genome sequencing using paired-end reads, in order to elucidate the molecular breakpoints. In a two-step analysis, we first narrowed down the region by identifying discordant read-pairs, and then determined the precise molecular breakpoint by analysing the mapping locations of “soft-clipped” breakpoint-spanning reads. PCR and Sanger sequencing confirmed the identified breakpoints, both of which were located in intergenic regions. Significantly, the 7p15 breakpoint was located 523 kb upstream of HOXA13, the locus for hand-foot-genital syndrome. By inference from studies of HOXA locus control in the mouse, we suggest that the inversion has delocalised a HOXA13 enhancer to produce the phenotype observed in our patient. This study demonstrates how modern genetic diagnostic approach can characterise structural variants at nucleotide resolution and provide potential insights into functional regulation.

Mammalian cadherins DCHS1-FAT4 affect functional cerebral architecture

Cortical development is a complex process where a multitude of factors, including cadherins, plays an important role and where disruptions are known to have far reaching effects in neural development and cortical patterning. Cadherins play a central role in structural left-right differentiation during brain and body development, but their effect on a functional level remains elusive. We addressed this question by examining functional cerebral asymmetries in a patient with Van Maldergem Syndrome (VMS) (MIM#601390), which is caused by mutations in DCHS1-FAT4 cadherins, using a dichotic listening task. Using neurophysiological (EEG) data, we show that when key regulators during mammalian cerebral cortical development are disrupted due to DCHS1-FAT4 mutations, functional cerebral asymmetries are stronger. Basic perceptual processing of biaurally presented auditory stimuli was unaffected. This suggests that the strength and emergence of functional cerebral asymmetries is a direct function of proliferation and differentiation of neuronal stem cells. Moreover, these results support the recent assumption that the molecular mechanisms establishing early left-right differentiation are an important factor in the ontogenesis of functional lateralization.

A 1.6-Mb microdeletion in chromosome 17q22 leads to NOG-related symphalangism spectrum disorder without intellectual disability

Microdeletions in chromosome 17q22, where the NOG gene resides, have been reported leading to the NOG-related symphalangism spectrum disorder (NOG-SSD), intellectual disability and other developmental abnormalities. In this study we reported a dominant Chinese Han family segregating with typical NOG-SSD symptoms including proximal symphalangism, conductive hearing loss, amblyopia and strabismus, but not intellectual disability. Sanger sequencing identified no pathogenic mutation in the coding regions of candidate genes NOG, GDF5 and FGF9. SNP genotyping in the genomic region surrounding NOG identified loss of heterozygosity in the affected family members. By array comparative genomic hybridization and quantitative real-time polymerase chain reaction, we identified and mapped the breakpoints of a novel 1.6-Mb microdeletion in chromosome 17q22 that included NOG and twelve other genes. It is the first microdeletion reported in chromosome 17q22 that is associated with NOG-SSD only but not with intellectual disability. Our results may help identifying the dosage sensitive genes for intellectual disability and other developmental abnormalities in chromosome 17q22. Our study also suggested that genomic deletions in chromosome 17q22 should be screened in the NOG-SSD patients in which no pathogenic mutation is identified by conventional sequencing methods.

Hearing loss in syndromic craniosynostoses: otologic manifestations and clinical findings

OBJECTIVE

This review addresses hearing loss as it occurs and has been reported in Muenke syndrome as well as six additional FGFR related craniosynostosis syndromes (Apert syndrome, Pfeiffer syndrome, Crouzon syndrome, Beare-Stevenson syndrome, Crouzon syndrome with acanthosis nigricans, and Jackson-Weiss syndrome.

DATA SOURCES

Pub-Med, Medline, Cochrane Database, Science Direct, NLM Catalog.

REVIEW METHODS

A Medline search was conducted to find all reported cases of the 7 FGFR related syndromic craniosynostosis. Special attention was paid to literature that reported hearing findings and the audiology literature.

RESULTS

Hearing loss occurs in variable percentage as a component part of all FGFR related craniosynostosis syndromes. Our literature review revealed the following incidences of hearing loss in FGFR craniosynostoses: 61% in Muenke syndrome, 80% in Apert Syndrome, 92% in Pfeiffer syndrome, 74% in Crouzon syndrome, 68% in Jackson Weiss syndrome, 4% in Beare Stevenson syndrome and 14% in Crouzon syndrome with Acanthosis Nigricans. The majority of the hearing loss is a conductive hearing loss, with the exception of Muenke syndrome where the majority of patients have a sensorineural hearing loss and Crouzon syndrome where almost half of patients have a pure or component of sensorineural hearing loss.

CONCLUSION

This manuscript presents a diagnostic and management algorithm for patients with syndromic craniosynostosis. It will aid clinicians in treating these patients and further, the recognition of a possible syndrome in patients with hearing loss who also have syndromic features.

Phenotype and genotype in Nicolaides-Baraitser syndrome

Nicolaides-Baraitser syndrome (NCBRS) is an intellectual disability (ID)/multiple congenital anomalies syndrome caused by non-truncating mutations in the ATPase region of SMARCA2, which codes for one of the two alternative catalytic subunits of the BAF chromatin remodeling complex. We analyzed 61 molecularly confirmed cases, including all previously reported patients (n = 47) and 14 additional unpublished individuals. NCBRS is clinically and genetically homogeneous. The cardinal features (ID, short stature, microcephaly, typical face, sparse hair, brachydactyly, prominent interphalangeal joints, behavioral problems and seizures), are almost universally present. There is variability however, as ID can range from severe to mild, and sparse hair may be present only in certain age groups. There may be a correlation between the severity of the ID and presence of seizures, absent speech, short stature and microcephaly. SMARCA2 mutations causing NCBRS are likely to act through a dominant-negative effect. There may be some genotype-phenotype correlations (mutations at domain VI with severe ID and seizures; mutations affecting residues Pro883, Leu946, and Ala1201 with mild phenotypes) but numbers are still too small to draw definitive conclusions.

Numerous BAF complex genes are mutated in Coffin-Siris syndrome

Coffin-Siris syndrome (CSS; OMIM#135900) is a rare congenital anomaly syndrome characterized by intellectual disability, coarse face, hypertrichosis, and absence/hypoplasia of the fifth digits' nails. As the majority of patients are sporadic, an autosomal dominant inheritance model has been postulated. Recently, whole exome sequencing (WES) emerged as a comprehensive analytical method for rare variants. We applied WES on five CSS patients and found two de novo mutations in SMARCB1. SMARCB1 was completely sequenced in 23 CSS patients and the mutations were found in two more patients. As SMARCB1 encodes a subunit of the BAF complex functioning as a chromatin remodeling factor, mutations in 15 other subunit genes may cause CSS and thus were analyzed in 23 CSS patients. We identified heterozygous mutations in either of six genes (SMARCA4, SMARCB1, SMARCA2, SMARCE1, ARID1A, and ARID1B) in 20 out of 23 CSS patients. The patient with a SMARCA2 mutation was re-evaluated and identified as having Nicolaides-Baraitser syndrome (OMIM#601358), which is similar to but different from CSS. Additionally, 49 more CSS patients were analyzed as a second cohort. Together with the first cohort, 37 out of 71 (22 plus 49) patients were found to have a mutation in either one of five BAF complex genes. Furthermore, two CSS patients were reported to have a PHF6 abnormality, which can also cause Borjeson-Forssman-Lehmann syndrome (OMIM#301900), an X-linked intellectual disability syndrome with epilepsy and endocrine abnormalities. The current list of mutated genes in CSS is far from being complete and analysis of more patients is required.

A novel autosomal recessive GJA1 missense mutation linked to Craniometaphyseal dysplasia

Craniometaphyseal dysplasia (CMD) is a rare sclerosing skeletal disorder with progressive hyperostosis of craniofacial bones. CMD can be inherited in an autosomal dominant (AD) trait or occur after de novo mutations in the pyrophosphate transporter ANKH. Although the autosomal recessive (AR) form of CMD had been mapped to 6q21-22 the mutation has been elusive. In this study, we performed whole-exome sequencing for one subject with AR CMD and identified a novel missense mutation (c.716G>A, p.Arg239Gln) in the C-terminus of the gap junction protein alpha-1 (GJA1) coding for connexin 43 (Cx43). We confirmed this mutation in 6 individuals from 3 additional families. The homozygous mutation cosegregated only with affected family members. Connexin 43 is a major component of gap junctions in osteoblasts, osteocytes, osteoclasts and chondrocytes. Gap junctions are responsible for the diffusion of low molecular weight molecules between cells. Mutations in Cx43 cause several dominant and recessive disorders involving developmental abnormalities of bone such as dominant and recessive oculodentodigital dysplasia (ODDD; MIM #164200, 257850) and isolated syndactyly type III (MIM #186100), the characteristic digital anomaly in ODDD. However, characteristic ocular and dental features of ODDD as well as syndactyly are absent in patients with the recessive Arg239Gln Cx43 mutation. Bone remodeling mechanisms disrupted by this novel Cx43 mutation remain to be elucidated.

Talocalcaneal coalition in Muenke syndrome: report of a patient, review of the literature in FGFR-related craniosynostoses, and consideration of mechanism

Muenke syndrome is an autosomal dominant craniosynostosis syndrome resulting from a defining point mutation in the Fibroblast Growth Factor Receptor3 (FGFR3) gene. Muenke syndrome is characterized by coronal craniosynostosis (bilateral more often than unilateral), hearing loss, developmental delay, and carpal and/or tarsal bone coalition. Tarsal coalition is a distinct feature of Muenke syndrome and has been reported since the initial description of the disorder in the 1990s. Although talocalcaneal coalition is the most common tarsal coalition in the general population, it has never previously been reported in a patient with Muenke syndrome. We present a 7-year-old female patient with Muenke syndrome and symptomatic talocalcaneal coalition. She presented at the age of 7 with limping, tenderness and pain in her right foot following a fall and strain of her right foot. She was treated with ibuprofen, shoe inserts, a CAM walker boot, and stretching exercises without much improvement in symptoms. A computed tomography (CT) scan revealed bilateral talocalcaneal coalitions involving the middle facet. She underwent resection of the talocalcaneal coalitions, remaining pain-free post-operatively with an improvement in her range of motion, gait, and mobility. This report expands the phenotype of tarsal coalition in Muenke syndrome to include talocalcaneal coalition. A literature review revealed a high incidence of tarsal coalition in all FGFR related craniosynostosis syndromes when compared to the general population, a difference that is statistically significant. The most common articulation involved in all syndromic craniosynostoses associated with FGFR mutations is the calcaneocuboid articulation.

Oro-facial-digital syndrome type II

Oro-facial-digital syndrome type II (OFD-II) is characterized by frenulated tongue, midline cleft lip, high arched or cleft palate, micrognathia, syndactyly and polydactyly, bilateral reduplicated hallux, conductive hearing loss, choroidal coloboma and normal intelligence. There are nine forms of oro-facial-digital syndromes with different modes of inheritance. A young female with features of oro-facio-digital syndrome type-II is being reported.

Madelung-like deformity in pseudohypoparathyroidism type 1b

CONTEXT

Pseudohypoparathyroidism (PHP) types 1a and 1b are distinguished by clinical, biochemical, and molecular features. We report extended kindred with PHP 1b in which many affected members also had growth plate defects, including brachydactyly and a Madelung-like deformity.

DESIGN

Analyses included clinical examination, assessment of mineral metabolism, thyroid function, skeletal radiography, and analysis of the GNAS and STX16 genes.

SETTING

Patients were studied in an academic medical center.

RESULTS

We studied 37 members of a family in which PHP 1b occurred in 23 individuals. Ten of 17 affected patients who were examined had brachydactyly E, including two subjects with Madelung-like defects. Five of 16 subjects had subclinical hypothyroidism; no subject showed sc ossification or short stature. None of the unaffected members had brachydactyly or an elevated serum level of PTH or TSH. Levels of immunoactive erythrocyte Gα(s) were normal in two affected subjects tested. Linkage analysis indicated linkage between PTH resistance and the GNAS gene locus; however, no mutations were identified in GNAS exons 1-13. Methylation analysis of genomic DNA from affected subjects showed loss of maternal epigenotype in exon 1A with normal methylation of the differentially methylated regions for XLGαs and NESP55, and PCR demonstrated heterozygosity for a 3.0-kb deletion in the STX16 gene.

CONCLUSION

The segregation of brachydactyly with PHP 1b in this family indicates that an imprinting defect in GNAS can lead to growth plate defects, including brachydactyly and Madelung deformity. These features suggest that GNAS signaling plays a more extensive role in chondrocyte maturation than previously thought.

Type II familial synpolydactyly: report on two families with an emphasis on variations of expression

Type II familial synpolydactyly is rare and is known to have variable expression. However, no previous papers have attempted to review these variations. The aim of this paper was to review these variations and show several of these variable expressions in two families. The classic features of type II familial synpolydactyly are bilateral synpolydactyly of the third web spaces of the hands and bilateral synpolydactyly of the fourth web spaces of the feet. Several members of the two families reported in this paper showed the following variations: the third web spaces of the hands showing syndactyly without the polydactyly, normal feet, concurrent polydactyly of the little finger, concurrent clinodactyly of the little finger and the 'homozygous' phenotype. It was concluded that variable expressions of type II familial synpolydactyly are common and awareness of such variations is important to clinicians.

Temtamy preaxial brachydactyly syndrome is caused by loss-of-function mutations in chondroitin synthase 1, a potential target of BMP signaling

Altered Bone Morphogenetic Protein (BMP) signaling leads to multiple developmental defects, including brachydactyly and deafness. Here we identify chondroitin synthase 1 (CHSY1) as a potential mediator of BMP effects. We show that loss of human CHSY1 function causes autosomal-recessive Temtamy preaxial brachydactyly syndrome (TPBS), mainly characterized by limb malformations, short stature, and hearing loss. After mapping the TPBS locus to chromosome 15q26-qterm, we identified causative mutations in five consanguineous TPBS families. In zebrafish, antisense-mediated chsy1 knockdown causes defects in multiple developmental processes, some of which are likely to also be causative in the etiology of TPBS. In the inner ears of zebrafish larvae, chsy1 is expressed similarly to the BMP inhibitor dan and in a complementary fashion to bmp2b. Furthermore, unrestricted Bmp2b signaling or loss of Dan activity leads to reduced chsy1 expression and, during epithelial morphogenesis, defects similar to those that occur upon Chsy1 inactivation, indicating that Bmp signaling affects inner-ear development by repressing chsy1. In addition, we obtained strikingly similar zebrafish phenotypes after chsy1 overexpression, which might explain why, in humans, brachydactyly can be caused by mutations leading either to loss or to gain of BMP signaling.

Loss of CHSY1, a secreted FRINGE enzyme, causes syndromic brachydactyly in humans via increased NOTCH signaling

We delineated a syndromic recessive preaxial brachydactyly with partial duplication of proximal phalanges to 16.8 Mb over 4 chromosomes. High-throughput sequencing of all 177 candidate genes detected a truncating frameshift mutation in the gene CHSY1 encoding a chondroitin synthase with a Fringe domain. CHSY1 was secreted from patients' fibroblasts and was required for synthesis of chondroitin sulfate moieties. Noticeably, its absence triggered massive production of JAG1 and subsequent NOTCH activation, which could only be reversed with a wild-type but not a Fringe catalytically dead CHSY1 construct. In vitro, depletion of CHSY1 by RNAi knockdown resulted in enhanced osteogenesis in fetal osteoblasts and remarkable upregulation of JAG2 in glioblastoma cells. In vivo, chsy1 knockdown in zebrafish embryos partially phenocopied the human disorder; it increased NOTCH output and impaired skeletal, pectoral-fin, and retinal development. We conclude that CHSY1 is a secreted FRINGE enzyme required for adjustment of NOTCH signaling throughout human and fish embryogenesis and particularly during limb patterning.

Brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome (OMIM 609945): case report and review of the literature

Brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome (OMIM 609945) is a rare congenital disorder. Only seven patients have been reported to date, and the etiology of this syndrome is unknown. Autosomal dominant inheritance with variable expression has been suggested based on the presence of minor features in some parents and the fact that neither parental consanguinity nor pairs of affected siblings were observed. We report on the first patient with this syndrome who was born to consanguineous parents. Neither the mother nor the father, who were first cousins, had clinical features suggestive of a manifestation of brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome. The patient had no siblings, and the family history was unremarkable. Clinical problems included brachydactyly of hands and feet, splaying of fingers and toes, preaxial polydactyly of feet, bilateral tibial aplasia, shortened radius and ulna, and characteristic facial dysmorphic signs. The detailed description of this patient adds to our knowledge of the clinical manifestations of brachyphalangy, polydactyly and tibial aplasia/hypoplasia syndrome and will eventually also contribute to the elucidation of the underlying gene defects.

Genotype-phenotype correlation in eight new patients with a deletion encompassing 2q31.1

Microdeletions of the 2q31.1 region are rare. We present the clinical and molecular findings of eight previously unreported patients with overlapping deletions in 2q31.1. The patients have a variable clinical phenotype and present with developmental delay (7/8), growth retardation (5/8), seizures (2/8) and a craniofacial dysmorphism consisting of microcephaly (4/8), short palpebral fissures (7/8), broad eyebrows with lateral flare (7/8), low-set ears with thickened helices and lobules (5/8), and micrognathia (6/8). Additional congenital anomalies were noted, including limb abnormalities (8/8), heart defects (3/8), genital anomalies (3/8), and craniosynostosis (1/8). Six of these microdeletions, ranging in size from 1.24 to 8.35 Mb, were identified by array CGH, one larger deletion (19.7 Mb) was detected by conventional karyotyping and further characterized by array CGH analysis. The smallest region of overlap in all eight patients spans at most 88 kb and includes only the WIPF1 gene. This gene codes for the WAS/WASL interacting protein family member 1. The patients described here do not present with clinical signs of the Wiskott-Aldrich syndrome and the deletion of this single gene does not allow explaining the phenotype in our patients. It is likely that the deletion of different but overlapping sets of genes from 2q31 is responsible for the clinical variability in these patients. To further dissect the complex phenotype associated with deletions in 2q31, additional patients with overlapping phenotypes should be examined with array CGH. This should help to link particular phenotypes to specific genes, and add to our understanding of the underlying developmental processes.

[Prevalence of congenital split hand/split foot malformation in Chinese population]

OBJECTIVE

To study the epidemiological and clinical features of congenital split hand/split foot malformation (SHFM) in Chinese population.

METHODS

Data used in this study were provided by the Chinese Birth Defects Monitoring Network. The SHFM cases were categorized into two groups: isolated (SHFM only and SHFM with other limb defects) and syndromic (SHFM with non-limb defects). Prevalence rates were calculated by residential area (urban versus rural) and by gender. Further analyses were conducted to identify the characteristics of SHFM with related to gestational age, birth weight, perinatal outcome and affected limbs.

RESULTS

A total of 736 newborn babies were identified with SHFM among 4,489,692 births, with a prevalence of 1.64/10,000. The prevalence of isolated SHFM and syndromic SHFM were 0.64 and 1.00 per 10,000 births, respectively. The prevalence of SHFM in male and female babies were 1.79 and 1.25 per 10,000 births, respectively. The prevalence of SHFM in urban and rural areas were 1.51 and 1.86 per 10,000 births, respectively. Preterm birth and low birth weight accounted for 30.20% and 43.93% of the SHFM cases, respectively. The perinatal mortality for the SHFM, isolated SHFM, and syndromic SHFM were 50.27%, 24.74%, and 66.59%, respectively. SHFM occurred more often in upper limbs.

CONCLUSION

The prevalence of SHFM in Chinese population is greater than foreign populations. The high perinatal mortality rate of SHFM is associated with the severity of accompanied malformations.

Characterization of the complex 7q21.3 rearrangement in a patient with bilateral split-foot malformation and hearing loss

We report on complex rearrangements of the 7q21.3 region in a female patient with bilateral split-foot malformation and hearing loss. G-banding karyotype was 46,XX,t(7;15)(q21;q15),t(9;14)(q21;q11.2)dn. By fluorescence, in situ hybridization (FISH), Southern hybridization, and inverse PCR, the 7q21.3 translocation breakpoint was determined at the nucleotide level. The breakpoint did not disrupt any genes, but was mapped to 38-kb telomeric to the DSS1 gene, and 258- and 272-kb centromeric to the DLX6 and DLX5 genes, respectively. It remains possible that the translocation would disrupt the interaction between these genes and their regulatory elements. Interestingly, microarray analysis also revealed an interstitial deletion close to (but not continuous to) the 7q21.3 breakpoint, indicating complex rearrangements within the split-hand/foot malformation 1 (SHFM1) locus in this patient. Furthermore, a 4.6-Mb deletion at 15q21.1-q21.2 adjacent to the 15q15 breakpoint was also identified. Cloning of the deletion junction at 7q21.3 revealed that the 0.8-Mb deletion was located 750-kb telomeric to the translocation breakpoint, encompassing TAC1, ASNS, OCM, and a part of LMTK2. Because TAC1, ASNS, and OCM genes were located on the reported copy number variation regions, it was less likely that the three genes were related to the split-foot malformation. LMTK2 appeared to be a potential candidate gene for SHFM1, but no LMTK2 mutations were found in 29 individuals with SHFM. Further LMTK2 analysis of SHFM patients together with hearing loss is warranted.

Cranio-osteoarthropathy: a rare variant of hypertrophic osteoarthropathy

AIM

To highlight the clinical features and diagnosis of cranio-osteoarthropathy, an extremely rare disease.

METHODS

Case report and literature review.

RESULT

A 2.3-year-old child presented with mild swelling of his distal phalanges at the age of 5 months that became pronounced gradually. His parents were consanguineous and his 14-year-old sister had albinism. Physical examination showed normal height and weight. A mild prominent nose, patent cranial sutures and anterior and posterior fontanel, clubbing of the digits without cyanosis, finger joint laxity, large nails, and mild knock-knee were noted. Radiographs showed wormian bones, patent cranial sutures, anterior and posterior fontanels, periostosis and wide diaphyses of long bone, abnormal curvature tibia.

CONCLUSION

Cranio-osteoarthropathy is an extremely rare occurrence and may be an autosomal-recessive inheritance. This diagnosis should be considered while a patient presented digital clubbing, periosteal new bone formation and decreased neurocranium ossification.

[Postaxial polydactyly of the foot: the six members of a family affected]

Foot polydactyly constitutes one of the most frequent congenital malformations. Any of its forms (preaxial, postaxial and central) can be associated with other syndromes or congenital disease. We report the case of a family in which all its members (a mother and her five children) showed a postaxial bilateral polydactylism, except a patient in whom the presentation was unilateral. Another one was associating in addition a postaxial unilateral polydactylism of the hand. All the patients with exception of the mother needed surgical treatment. It is not common to find in the literature relating to the postaxial polydactyly of the foot, families with a number so raised of cases, being the incidence of 100% in this case. Due to the high prevalence of this disease, it is important to standardize an anatomical classification in order to elaborate suitable surgical protocols.

Monosomy 5p and trisomy 12p in a boy with familial balanced translocation

We report on a boy with monosomy 5p involving the Cri-du-Chat critical region and trisomy 12p detected by subtelomere study. Familial studies showed that the boy's mother and paternal grandfather had a balanced reciprocal translocation between the short arm of chromosomes 5 and 12. The boy had an overlap of features of both chromosomal conditions, even though the Cri-du-Chat phenotype was more prominent.

Central ray deficiency with extensive syndactyly: a dilemma for classification

Split Hand Foot Malformation (SHFM) (cleft hand/foot, central ray deficiency) is a complex, highly variable anomaly involving the hands and/or feet. A clinical epidemiologic study of split hand/foot (central ray deficiency) of the Manitoba population identified a subset of patients who did not present with either typical or atypical split hand. Clinically, some patients presented with "mitten hand" syndactyly; the deficiency was not recognized before imaging. In this paper, we identify additional similarly affected literature cases, review existing classifications of split hand and syndactyly and attempt to classify these patients. This group presents a challenge for classification and genetic counseling. General classifications permit inclusion of patients with diverse phenotypes; however, details are overlooked. Osseous fusions and disorganization of osseous components complicate classification. Many of these patients had findings that overlapped different subtypes within existing classifications. This cohort highlights the importance of imaging patients with distal limb anomalies. An effective classification scheme should include relevant clinical and radiographic findings in order to assist clinicians following these patients.

Brachydactyly

Brachydactyly ("short digits") is a general term that refers to disproportionately short fingers and toes, and forms part of the group of limb malformations characterized by bone dysostosis. The various types of isolated brachydactyly are rare, except for types A3 and D. Brachydactyly can occur either as an isolated malformation or as a part of a complex malformation syndrome. To date, many different forms of brachydactyly have been identified. Some forms also result in short stature. In isolated brachydactyly, subtle changes elsewhere may be present. Brachydactyly may also be accompanied by other hand malformations, such as syndactyly, polydactyly, reduction defects, or symphalangism. For the majority of isolated brachydactylies and some syndromic forms of brachydactyly, the causative gene defect has been identified. In isolated brachydactyly, the inheritance is mostly autosomal dominant with variable expressivity and penetrtance. Diagnosis is clinical, anthropometric and radiological. Prenatal diagnosis is usually not indicated for isolated forms of brachydactyly, but may be appropriate in syndromic forms. Molecular studies of chorionic villus samples at 11 weeks of gestation and by amniocentesis after the 14th week of gestation can provide antenatal diagnosis if the causative mutation in the family is known. The nature of genetic counseling depends both on the pattern of inheritance of the type of brachydactyly present in the family and on the presence or absence of accompanying symptoms. There is no specific management or treatment that is applicable to all forms of brachydactyly. Plastic surgery is only indicated if the brachydactyly affects hand function or for cosmetic reasons, but is typically not needed. Physical therapy and ergotherapy may ameliorate hand function. Prognosis for the brachydactylies is strongly dependent on the nature of the brachydactyly, and may vary from excellent to severely influencing hand function. If brachydactyly forms part of a syndromic entity, prognosis often depends on the nature of the associated anomalies.

Merosin-deficient congenital muscular dystrophy type 1A

Merosin-deficient congenital muscular dystrophy type 1A (MDC1A) is the most common form of congenital muscular dystrophy. MDC1A is caused by mutation of the laminin alpha-2 gene (LAMA2), localized to chromosome 6q22-23. The diagnosis of merosin-deficient CMD is based on the clinical findings of severe congenital hypotonia, weakness, with high blood levels of creatine kinase, WM abnormalities, and dystrophy associated with negative immunostaining of biopsied muscle for merosin. We investigated clinical and laboratory a patient: a girl with merosin-deficient congenital muscular dystrophy type 1A. Clinically the particularity of the case is the association of merosin-negative congenital muscular dystrophy (MN-CMD) with congenital feet deformity. The level of serum creatine kinase is elevated 1045 U/L. Immunohistochemistry show presence of dystrophin, lack of merosin, also the utrophin is normally expressed. Nerve conduction studies are normally, while electromyography suggested a myopathic process with early recruitment and decreased amplitude and duration of response. Magnetic resonance imaging: MRI T1 and MRI T2 show hypointensity and diffuse hyperintensity respectively in the white matter. Supratentorial MRI images showed hypotrophy of the corpus callosum and almost absent cingulate gyrus. In addition, hypophysis is reduced size.

Prune belly anomaly on prenatal ultrasound as a presenting feature of ectrodactyly-ectodermal dysplasia-clefting syndrome (EEC)

We report on a fetus with prune belly anomaly presenting at 16 weeks gestation. Clinical evaluation after birth revealed other malformations reminiscent of the EEC syndrome. This diagnosis was also suspected in the mother and finally confirmed in both relatives by identification of a heterozygous mutation (p.R204W) in the p63 gene. With this paper we confirm the previously reported occurrence of prune belly anomaly in the EEC syndrome, however here in this family proven by genetic analysis.

[Genetic analysis of a Chinese pedigree with split hand and foot malformation]

OBJECTIVE

To analyze the clinical manefestation and genetic basis of split hand and foot malformation (SHFM) in a Chinese pedigree.

METHODS

The affected people in the family were checked by X-rays. Eighteen patients provided their peripheral blood, and the genomic DNA of the samples was extracted. The linkage and haplotype analysis were carried out using the microsatellite markers, and the limb malformation related gene Dactylin (DAC) including the coding region, exon-intron boundaries and part of promoter region was sequenced.

RESULTS

Most members of the family with the disease phenotype showed absence or hypoplasia of the index finger, and absence or 3-4 syndactyly of the middle finger. The degree of abnormality in feet was severer than that in hands. All phenotypes of the patients display the basic characters of SHFM. Since the maximum two point LOD score of the D10S192 was 3.50 (theta=0.00), the SHFM in this pedigree can be categorized to the SHFM3. The haplotype analysis of recombination events revealed the candidate locus to a 21cM region between D10S185 and D10S1693. No mutation was found by the sequencing result of DAC gene.

CONCLUSION

Through the analysis of phenotype of the patients, the typical SHFM disease can be confirmed. The linkage and haplotype analysis demonstrated that the 21cM region in 10q23-q26 locus was the major cause to the disease in this pedigree. The mutation of DAC gene can be excluded from cause of SHFM3 phenotype.

Abnormal urethra formation in mouse models of split-hand/split-foot malformation type 1 and type 4

Urogenital birth defects are one of the common phenotypes observed in hereditary human disorders. In particular, limb malformations are often associated with urogenital developmental abnormalities, as the case for Hand-foot-genital syndrome displaying similar hypoplasia/agenesis of limbs and external genitalia. Split-hand/split-foot malformation (SHFM) is a syndromic limb disorder affecting the central rays of the autopod with median clefts of the hands and feet, missing central fingers and often fusion of the remaining ones. SHFM type 1 (SHFM1) is linked to genomic deletions or rearrangements, which includes the distal-less-related homeogenes DLX5 and DLX6 as well as DSS1. SHFM type 4 (SHFM4) is associated with mutations in p63, which encodes a p53-related transcription factor. To understand that SHFM is associated with urogenital birth defects, we performed gene expression analysis and gene knockout mouse model analyses. We show here that Dlx5, Dlx6, p63 and Bmp7, one of the p63 downstream candidate genes, are all expressed in the developing urethral plate (UP) and that targeted inactivation of these genes in the mouse results in UP defects leading to abnormal urethra formation. These results suggested that different set of transcription factors and growth factor genes play similar developmental functions during embryonic urethra formation. Human SHFM syndromes display multiple phenotypes with variations in addition to split hand foot limb phenotype. These results suggest that different genes associated with human SHFM could also be involved in the aetiogenesis of hypospadias pointing toward a common molecular origin of these congenital malformations.

Novel mutations of the HOXD13 gene in hand and foot malformations

Homeobox genes encode a set of transcription factors of fundamental importance for body patterning during embryogenesis. Hoxa9-a13 and Hoxd9-d13 play an especially important part in vertebrate limb development. Synpolydactyly (SPD) is characterized by various malformations of the limbs. The expansion of the polyalanine tract in 1OXD13 is one of its major causes. Recently, there have been many analysis studies of HOXD13 in patients with SPD and limb malformations. We analyzed HOXD13 in 100 patients with limb malformations, which affects the limbs in the distal parts of the metacarpal and/or metatarsal bones. Seven mutations in the coding region and two mutations in the 5'-untranslated region were identified. All were novel mutations. In this study, the mutations were located upstream in the homeobox. Thus, translation of the homeobox was affected by upstream mutations. Consequently, this suggested the possibility that abnormalities in the hands and feet could be caused by novel HOXD13 gene mutations.

A novel mutation of p63 in a Chinese family with inherited syndactyly and adactylism

p63 is a transcription factor homologous to p53 and p73; mutations in this gene have been identified in individuals with several types of developmental abnormalities, including EEC (ectrodactyly, ectodermal dysplasia, facial clefts) syndrome and split-hand/split-foot malformation (SHFM). Several mutations in the p63 gene have previously been shown to be related to SHFM. In this study, we report on a Chinese family with intrafamilial clinical variability of SHFM that have a novel heterozygous mutation in all four affected individuals. The mutation is in exon 8 of p63, 1046G --> A, which predicts an amino acid substitution G310E. SSCP analysis of the segregation pattern of the mutation strongly suggests a causal relationship to the SHFM phenotype in p63. This mutation has not been observed in other countries in the world.

A new locus for split hand/foot malformation with long bone deficiency (SHFLD) at 2q14.2 identified from a chromosome translocation

Split hand/foot malformation (SHFM) with long bone deficiency (SHFLD) is a distinct entity in the spectrum of ectrodactylous limb malformations characterised by associated tibial a/hypoplasia. Pedigrees with multiple individuals affected by SHFLD often include non-penetrant intermediate relatives, making genetic mapping difficult. Here we report a sporadic patient with SHFLD who carries a de novo chromosomal translocation t(2;18)(q14.2;p11.2). Characterisation of the breakpoints revealed that neither disrupts any known gene; however, the chromosome 2 breakpoint lies between GLI2 and INHBB, two genes known to be involved in limb development. To investigate whether mutation of a gene in proximity to the chromosome 2 breakpoint underlies the SHFLD, we sought independent evidence of mutations in GLI2, INHBB and two other genes (RALB and FLJ14816) in 44 unrelated patients with SHFM, SHFLD or isolated long bone deficiency. No convincing pathogenic mutations were found, raising the possibility that a long-range cis acting regulatory element may be disrupted by this translocation. The previous description of a translocation with a 2q14.2 breakpoint associated with ectrodactyly, and the mapping of the ectrodactylous Dominant hemimelia mouse mutation to a region of homologous synteny, suggests that 2q14.2 represents a novel locus for SHFLD.