Dataset Information

A New Split Hand/Foot Malformation with Long Bone Deficiency Familial Case.

ABSTRACT: Split hand/foot malformation with long bone deficiency (SHFLD) is a congenital limb anomaly where hands and/or feet cleft and syndactyly are associated with long bone defects, usually involving the tibia. Previously published data reported that 17p13.3 chromosomal duplication, including the BHLHA9 gene, has been associated with the distinct entity, termed SHFLD3 (OMIM 612576), inherited as an autosomal dominant trait. Here, we present a family with three members affected by SHFLD harboring BHLHA9 duplication. We exploited in vitro differentiation system to promote proband's skin fibroblasts toward osteoblastic lineage, and we observed a slight but consistent delay in the mineralization pattern. This result possibly suggests an impairment of the osteogenic process in the affected members.

SUBMITTER: Fusco C

PROVIDER: S-EPMC5423807 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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A New Split Hand/Foot Malformation with Long Bone Deficiency Familial Case.

Fusco Carmela C Nittis Pasquelena De P Alfaiz Ali Abdullah AA Pellico Maria Teresa MT Augello Bartolomeo B Malerba Natascia N Zelante Leopoldo L Reymond Alexandre A Merla Giuseppe G

Journal of pediatric genetics 20160831 2

Split hand/foot malformation with long bone deficiency (SHFLD) is a congenital limb anomaly where hands and/or feet cleft and syndactyly are associated with long bone defects, usually involving the tibia. Previously published data reported that 17p13.3 chromosomal duplication, including the <i>BHLHA9</i> gene, has been associated with the distinct entity, termed SHFLD3 (OMIM 612576), inherited as an autosomal dominant trait. Here, we present a family with three members affected by SHFLD harborin ...[more]

PMID: 28496997

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Project description:BACKGROUND:Limb 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. METHODS:This 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. RESULTS:We 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. CONCLUSIONS:These 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.

Project description:BackgroundSplit hand/foot malformation (SHFM) is a genetically heterogeneous limb malformation with variable expressivity. SHFM with tibia or femur aplasia is called SHFM with long bone deficiency (SHFLD). 17p13.3 duplications containing BHLHA9 are associated with SHFLD. Cases with variable SHFLD phenotype and different 17p13.3 duplicated regions are reported. The severity of long bone defect could not be simply explained by BHLHA9 overdosage or 17p13.3 duplication.MethodsA four-generation Chinese SHFM family was recruited. Three family members have long bone defects, one male was severely affected with hypoplasia or aplasia in three of four limbs. Linkage analysis and direct sequencing of candidate genes were used to exclude six responsible genes/loci for isolated SHFM. Array comparative genomic hybridization (CGH) was performed to detect copy number variations on a genome-wide scale, and quantitative real-time polymerase chain reaction (qPCR) assays were designed to validate the identified copy number variation in the index and other family members.ResultsNo mutations were found in genes or loci linked to isolated SHFM. A ~ 966 kb duplication was identified in 17p13.3 by array CGH, in which BHLHA9 surrounding region presented as triplication. The qPCR assays confirmed the indicated 17p13.3 duplication as well as BHLHA9 triplication in all available affected family members and other two asymptomatic carriers. Given the incomplete penetrance in SHFLD, those two carriers were regarded as non-penetrant, which suggested that the genomic rearrangement was co-segregated with malformation in this family.ConclusionsThe present study reports an additional SHFLD family case with 17p13.3 genomic rearrangement. To our knowledge, the 966 kb genomic rearrangement is larger in size than any previously reported SHFLD-associated 17p13.3 duplication, and the present family shows marked phenotypic variability with two asymptomatic carriers and one patient with an extremely severe phenotype. This rare case provides the opportunity to identify underlying genotype-phenotype correlations between SHFLD and 17p13.3 genomic rearrangement.

Dataset Information

A New Split Hand/Foot Malformation with Long Bone Deficiency Familial Case.

Publications

A New Split Hand/Foot Malformation with Long Bone Deficiency Familial Case.

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