Loss-of-function mutations in CHST14, dermatan 4-O-sulfotransferase 1 (D4ST1) deficiency, have recently been found to cause adducted thumb-clubfoot syndrome (ATCS; OMIM#601776) and a new type of Ehlers-Danlos syndrome (EDS) coined as EDS Kosho Type (EDSKT) [Miyake et al., 2010], as well as a subset of kyphoscoliosis type EDS without lysyl hydroxylase deficiency (EDS VIB) coined as musculocontractural EDS (MCEDS) [Malfait et al., 2010]. Lack of detailed clinical information from later childhood to adulthood in ATCS and lack of detailed clinical information from birth to early childhood in EDSKT and MCEDS have made it difficult to determine whether these disorders would be distinct clinical entities or a single clinical entity with variable expressions and with different presentations depending on the patients' ages at diagnosis. We present detailed clinical findings and courses of two additional unrelated patients, aged 2 years and 6 years, with EDSKT with a comprehensive review of 20 reported patients with D4ST1 deficiency, which supports the notion that these disorders constitute a clinically recognizable form of EDS. The disorder, preferably termed D4ST1-deficient EDS, is characterized by progressive multisystem fragility-related manifestations (joint dislocations and deformities, skin hyperextensibility, bruisability, and fragility; recurrent large subcutaneous hematomas, and other cardiac valvular, respiratory, gastrointestinal, and ophthalmological complications) resulting from impaired assembly of collagen fibrils, as well as various malformations (distinct craniofacial features, multiple congenital contractures, and congenital defects in cardiovascular, gastrointestinal, renal, ocular, and central nervous systems) resulting from inborn errors of development.

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Wolf–Hirschhorn syndrome (WHS) is a contiguous gene deletion syndrome of the distal 4p chromosome, characterized by craniofacial features, growth impairment, intellectual disability, and seizures. Although genotype–phenotype correlation studies have previously been published, several important issues remain to be elucidated including seizure severity. We present detailed clinical and molecular‐cytogenetic findings from a microarray and fluorescence in situ hybridization (FISH)‐based genotype–phenotype analysis of 22 Japanese WHS patients, the first large non‐Western series. 4p deletions were terminal in 20 patients and interstitial in two, with deletion sizes ranging from 2.06 to 29.42 Mb. The new Wolf–Hirschhorn syndrome critical region (WHSCR2) was deleted in all cases, and duplication of other chromosomal regions occurred in four. Complex mosaicism was identified in two cases: two different 4p terminal deletions; a simple 4p terminal deletion and an unbalanced translocation with the same 4p breakpoint. Seizures began in infancy in 33% (2/6) of cases with small (<6 Mb) deletions and in 86% (12/14) of cases with larger deletions (>6 Mb). Status epilepticus occurred in 17% (1/6) with small deletions and in 87% (13/15) with larger deletions. Renal hypoplasia or dysplasia and structural ocular anomalies were more prevalent in those with larger deletions. A new susceptible region for seizure occurrence is suggested between 0.76 and 1.3 Mb from 4pter, encompassing CTBP1 and CPLX1, and distal to the previously‐supposed candidate gene LETM1. The usefulness of bromide therapy for seizures and additional clinical features including hypercholesterolemia are also described. © 2013 Wiley Periodicals, Inc.

BackgroundLimb malformations are rare disorders with high genetic heterogeneity. Although multiple genes/loci have been identified in limb malformations, underlying genetic factors still remain to be determined in most patients.MethodsThis study consisted of 51 Japanese families with split-hand/foot malformation (SHFM), SHFM with long bone deficiency (SHFLD) usually affecting the tibia, or Gollop-Wolfgang complex (GWC) characterized by SHFM and femoral bifurcation. Genetic studies included genomewide array comparative genomic hybridization and exome sequencing, together with standard molecular analyses.ResultsWe identified duplications/triplications of a 210,050 bp segment containing BHLHA9 in 29 SHFM patients, 11 SHFLD patients, two GWC patients, and 22 clinically normal relatives from 27 of the 51 families examined, as well as in 2 of 1,000 Japanese controls. Families with SHFLD- and/or GWC-positive patients were more frequent in triplications than in duplications. The fusion point was identical in all the duplications/triplications and was associated with a 4 bp microhomology. There was no sequence homology around the two breakpoints, whereas rearrangement-associated motifs were abundant around one breakpoint. The rs3951819-D17S1174 haplotype patterns were variable on the duplicated/triplicated segments. No discernible genetic alteration specific to patients was detected within or around BHLHA9, in the known causative SHFM genes, or in the exome.ConclusionsThese results indicate that BHLHA9 overdosage constitutes the most frequent susceptibility factor, with a dosage effect, for a range of limb malformations at least in Japan. Notably, this is the first study revealing the underlying genetic factor for the development of GWC, and demonstrating the presence of triplications involving BHLHA9. It is inferred that a Japanese founder duplication was generated through a replication-based mechanism and underwent subsequent triplication and haplotype modification through recombination-based mechanisms, and that the duplications/triplications with various haplotypes were widely spread in Japan primarily via clinically normal carriers and identified via manifesting patients. Furthermore, genotype-phenotype analyses of patients reported in this study and the previous studies imply that clinical variability is ascribed to multiple factors including the size of duplications/triplications as a critical factor.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-014-0125-5) contains supplementary material, which is available to authorized users.

Mowat-Wilson syndrome (MWS) is a multiple congenital anomaly syndrome characterized by moderate or severe intellectual disability, a characteristic facial appearance, microcephaly, epilepsy, agenesis or hypoplasia of the corpus callosum, congenital heart defects, Hirschsprung disease, and urogenital/renal anomalies. It is caused by de novo heterozygous loss of function mutations including nonsense mutations, frameshift mutations, and deletions in ZEB2 at 2q22. ZEB2 encodes the zinc finger E-box binding homeobox 2 protein consisting of 1,214 amino acids. Herein, we report 13 nonsense and 27 frameshift mutations from 40 newly identified MWS patients in Japan. Although the clinical findings of all the Japanese MWS patients with nonsense and frameshift mutations were quite similar to the previous review reports of MWS caused by nonsense mutations, frameshift mutations and deletions of ZEB2, the frequencies of microcephaly, Hirschsprung disease, and urogenital/renal anomalies were small. Patients harbored mutations spanning the region between the amino acids 55 and 1,204 in wild-type ZEB2. There was no obvious genotype-phenotype correlation among the patients. A transfection study demonstrated that the cellular level of the longest form of the mutant ZEB2 protein harboring the p.D1204Rfs*29 mutation was remarkably low. The results showed that the 3'-end frameshift mutation of ZEB2 causes MWS due to ZEB2 instability.

Primary microcephaly (MCPH) is an autosomal recessive disorder characterized by congenital reduction of head circumference. Here, we identified compound heterozygous mutations c.731 C > T (p.Ser 244 Leu) and c.2413 G > T (p.Glu 805 X) in the WDR62/MCPH2 gene, which encodes the mitotic centrosomal protein WDR62, in two siblings in a Japanese family with microcephaly using whole-exome sequencing. However, the molecular and cellular pathology of microcephaly caused by WDR62/MCPH2 mutation remains unclear. To clarify the physiological role of WDR62, we used the CRISPR/Cas9 system and single-stranded oligonucleotides as a point-mutation-targeting donor to generate human cell lines with knock-in of WDR62/MCPH2 c.731 C > T (p.Ser 244 Leu) missense mutation. In normal metaphase, the mitotic spindle forms parallel to the substratum to ensure symmetric cell division, while WDR62/MCPH2-mutated cells exhibited a randomized spindle orientation caused by the impaired astral microtubule assembly. It was shown that a mitotic kinase, Polo-like kinase 1 (PLK1), is required for the maintenance of spindle orientation through astral microtubule development. In this study, we demonstrated that WDR62 is a PLK1 substrate that is phosphorylated at Ser 897, and that this phosphorylation at the spindle poles promotes astral microtubule assembly to stabilize spindle orientation. Our findings provide insights into the role of the PLK1-WDR62 pathway in the maintenance of proper spindle orientation.

It is debatable whether Hajdu-Cheney syndrome (HCS) and serpentine fibula-polycystic kidney syndrome (SFPKS) represent a single clinical entity with a variable degree of expression or two different entities, because both disorders share common clinical and radiological manifestations, including similar craniofacial characteristics, and defective bone mineralization. Since it was shown that heterozygous truncating mutations in NOTCH2 are responsible for both HCS and SFPKS, 37 patients with HCS and four patients with SFPKS are reported. To elucidate the clinical consequences of NOTCH2 mutations, we present detailed clinical information for seven patients with truncating mutations in exon 34 of NOTCH2, six with HCS and one with SFPKS. In addition, we review all the reported patients whose clinical manifestations are available. We found 13 manifestations including craniofacial features, acroosteolysis, Wormian bones, and osteoporosis in >75% of NOTCH2-positive patients. Acroosteolysis was observed in two patients with SFPKS and bowing fibulae were found in two patients with HCS. These clinical and molecular data would support the notion that HCS and SFPKS are a single disorder.