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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.

Background Cenani‐Lenzsyndactyly syndrome (CLSS; OMIM 212780) is a rare autosomal recessive acral deformity, which is mainly manifested in the fusion of fingers or toes, disordered phalangeal structure, shortening or fusion of the radius and ulna, and renal hypoplasia. Case presentation Our report described an individual with mild phenotypes from China. His parents were not consanguineous. The affected individual was non‐dysmorphic. Standard X‐ray showed that the both hands have only four metacarpal bones. The distal end of the first metacarpal bone on the right was relatively slender, and the distal phalanx was absent. Multiple phalanges and some soft tissues of both hands were fused. Exome sequencing revealed a novel biallelic c.282C⟩Avariant in low‐density lipoprotein receptor‐related protein 4 (LRP4; OMIM604270; NM_002334.4) causing p. (Asn94Lys) change in the encoded protein. This variant is predicted to be potentially pathogenic, affecting protein structure and function. Conclusion We report a novel missense variant present in homozygosity in LRP4 to broaden the pathogenic spectrum of LRP4 in syndactyly, and exome sequencing technology is a powerful tool for genetic analysis in prenatal diagnosis and medical research, as a preferred method for the diagnosis of syndactyly and related phenotypes. Cenani‐Lenz syndactyly syndrome (CLSS; OMIM 212780) is a rare autosomal recessive acral deformity, we report a novel missense variant present in homozygosity in LRP4 to broaden the pathogenic spectrum of LRP4 in syndactyly. This variant is predicted to be potentially pathogenic, affecting protein structure and function.

IntroductionFraser syndrome, named after George Fraser, is an autosomal recessive disorder showing a highly variable interfamilial phenotypic variation, with malformations ranging from minor symptoms to lethal anomalies like renal agenesis, incompatible with survival. Limb reduction defects have not been reported to be associated with it.Case presentationA 21-year-old primigravida presented to the antenatal outpatient department with a level two targeted anomaly scan report suggestive of severe oligohydramnios with suspected renal agenesis. The cranial vault bones were compressed, and orbital globes and lenses could not be visualized. Renal agenesis was confirmed due to sleeping adrenals sign, non-visualization of the urinary bladder, and Doppler of renal arteries. A detailed examination of the fetal head in the sagittal section showed the absence of an eye globe and lens, arousing suspicion of Fraser syndrome. After pregnancy termination, a complete fetal autopsy was done to look for any additional findings.ConclusionPatients who have a syndromic mix of acrofacial and urogenital abnormalities with or without cryptophthalmos should be evaluated for Fraser syndrome, which can be diagnosed by clinical examination and perinatal autopsy.

Background Cenani–Lenz syndrome (CLS) is an autosomal recessive condition characterised by a unique pattern of syndactyly, and variable penetrance of renal agenesis and facial dysmorphism. LRP4 mutations were identified in most, but not all patients with this syndrome, suggesting the presence of at least one additional locus. Materials and methods Clinical characterisation of a new CLS family followed by autozygosity mapping, whole-exome sequencing and global gene expression profiling. Results We describe an extended consanguineous Saudi family with typical CLS features in addition to significant scoliosis. The disease in this family maps to a single autozygous interval on 5q22.2, in which whole-exome sequencing revealed the presence of a novel splicing mutation in APC that results in ∼80% reduction of the wild-type transcript and the creation of an aberrant transcript that predicts a severely truncated APC. This was found to be associated with upregulation of Wnt/β-catenin signalling. Conclusions In a pattern similar to how LRP4 mutations are predicted to negate the protein's antagonistic effect on Wnt/β-catenin signalling, we propose that reduction of APC may increase the availability of β-catenin by virtue of impaired degradation, leading to a similar phenotypic outcome. This is the first time APC is linked to a human phenotype distinct from its established role in oncology.

Rubinstein-Taybi syndrome (RTS, OMIM 180849) and Filippi syndrome (FLPIS, OMIM 272440) are both rare syndromes, with multiple congenital anomalies and intellectual deficit (MCA/ID). We present a patient with intellectual deficit, short stature, bilateral syndactyly of hands and feet, broad thumbs, ocular abnormalities, and dysmorphic facial features. These clinical features suggest both RTS and FLPIS. Initial DNA analysis of DNA isolated from blood did not identify variants to confirm either of these syndrome diagnoses. Whole-exome sequencing identified a homozygous variant in C9orf173, which was novel at the time of analysis. Further Sanger sequencing analysis of FLPIS cases tested negative for CKAP2L variants did not, however, reveal any further variants. Subsequent analysis using DNA isolated from buccal mucosa revealed a mosaic variant in CREBBP. This report highlights the importance of excluding mosaic variants in patients with a strong but atypical clinical presentation of a MCA/ID syndrome if no disease-causing variants can be detected in DNA isolated from blood samples. As the striking syndactyly observed in the present case is typical for FLPIS, we suggest CREBBP analysis in saliva samples for FLPIS syndrome cases in which no causal CKAP2L variant is detected.

Oculodentodigital dysplasia (ODDD) is a rare congenital disorder characterised by developmental abnormalities of the eye, dentition and digits of the hands and feet, with neurological symptoms reported in 30% of individuals. Dental anomalies associated with ODDD include enamel hypoplasia and subsequent caries, microdontia, missing teeth, amelogenesis imperfecta, pulp stones and delayed tooth development. Here, we describe the comprehensive dental management of a 3-year-old girl who presented with rapid deterioration of the primary dentition due to generalised enamel hypomineralisation. Conservative, comprehensive restorative management was performed under general anaesthesia. Within 6 months, further breakdown of the remaining unrestored enamel was noted. This case documents the challenges of conservative management in dental anomalies that are not well documented due to the extreme rarity of the disorder.

Background Long-QT syndrome (LQTS) causes a prolongation of the QT-interval in the ECG leading to life threatening tachyarrhythmia and ventricular fibrillation. One atypical form of LQTS, Timothy syndrome (TS), is associated with syndactyly, immune deficiency, cognitive and neurological abnormalities as well as distinct cranio-facial abnormalities. Case presentation On a family with both children diagnosed with clinical LQTS, we performed whole exome sequencing to comprehensively screen for causative mutations after a targeted candidate gene panel screen for Long-QT syndrome target genes failed to identify any underlying genetic defect. Using exome sequencing, we identified in both affected children, a p.402G > S mutation in exon 8 of the CACNA1C gene, a voltage-dependent Ca 2+ channel. The mutation was inherited from their father, a mosaic mutation carrier. Based on this molecular finding and further more careful clinical examination, we refined the diagnosis to be Timothy syndrome (TS2) and thereby were able to present new therapeutic approaches. Conclusions Our study highlights the difficulties in accurate diagnosis of patients with rare diseases, especially those with atypical clinical manifestation. Such challenge could be addressed with the help of comprehensive and unbiased mutation screening, such as exome sequencing.

Context: Although congenital hand anomalies are among the more common musculoskeletal anomalies worldwide, we do not know its prevalence in our practice. Aims: The aim of the study was to determine the pattern of congenital hand anomalies presenting to our tertiary plastic surgery outpatient service in South-Western Nigeria. Materials and Methods: This is a cross-sectional retrospective analysis of outpatient cases of congenital hand anomalies presenting over a 10-year period. Descriptive and inferential statistics were performed using frequencies, Student's t-test and Chi-square as appropriate. The data were analysed using IBM SPSS Statistics 23.0. The statistical significance value was set at P < 0.05. Results: One hundred and twenty-two cases were identified. The highest number of cases was seen in the year 2012, 23 patients (19.3%). There was a male preponderance of 66 patients (55.1%). Thirty-two patients (26.2%) presented as neonates and 36 (29.5%) as infants. Bilateral anomalies were seen in 67 patients (54.9%). The most common anomaly was failure of differentiation, 88 patients (72.1%) followed by duplication, 26 patients (21.3%). Syndactyly with 43 patients (35.2%) was the most common anomaly under failure of differentiation. No significant associations were found between the type of anomaly and gender or laterality. Conclusions: Syndactyly was the most common congenital hand anomaly in this study. There was a preponderance of bilateral involvement in both syndactyly and polydactyly.

Syndactyly is one of the most common hereditary limb malformations, and is characterized by the fusion of specific fingers and/or toes. Syndactyly type I-c is associated with bilateral cutaneous or bony webbing of the third and fourth fingers and occasionally of the third to fifth fingers, with normal feet. The aim of the present study was to identify the genetic basis of syndactyly type I-c in four generations of a Chinese Han family by exome sequencing. Exome sequencing was conducted in the proband of the family, followed by direct sequencing of other family members of the same ancestry, as well as 100 ethnically-matched, unrelated normal controls. A missense mutation, c.917G>A (p.R306Q), was identified in the homeobox D13 gene (HOXD13). Sanger sequencing verified the presence of this mutation in all of the affected family members. By contrast, this mutation was absent in the unaffected family members and the 100 ethnically-matched normal controls. The results suggest that the c.917G>A (p.R306Q) mutation in the HOXD13 gene, may be responsible for syndactyly type I-c in this family. Exome sequencing may therefore be a powerful tool for identifying mutations associated with syndactyly, which is a disorder with high genetic and clinical heterogeneity. The results provide novel insights into the etiology and diagnosis of syndactyly, and may influence genetic counseling and the clinical management of the disease.