Molecular Genetic Characterization of a Chinese Family with Severe Split Hand/Foot Malformation

Split hand/foot malformation (SHFM) is a congenital limb malformation characterized by underdeveloped or absent central digital rays, clefts of the hands and feet, and variable syndactyly of the remaining digits. SHFM is a genetically heterogeneous disease; the aim of this study was to identify pathogenic variations in a Chinese family with SHFM.

Haplotype analyses with microsatellite markers covering the five SHFM loci were performed to localize the causative locus. Real-time quantitative polymerase chain reaction (qPCR) assays and inverse PCR were performed to determine the copy number variations and to amplify junction breakpoints in affected individuals. Candidate genes were further screened for mutations through Sanger sequencing.

A potential haplotype in the SHFM3 locus was shared by all affected individuals. qPCR and inverse PCR showed a microduplication at chromosome 10q24 spanning 488,859 bp and encompassing five entire genes, LBX1, BTRC, POLL, DPCD, and FBXW4, that co-segregated with the SHFM phenotype. No coding or splice-site mutations of these genes were found.

We determined the molecular basis of SHFM in a Chinese family by haplotype analysis, qPCR, inverse PCR, and Sanger sequencing. Our work extends the clinical spectrum of SHFM3; provides a fine-scale delineation of the chromosomal breakpoints helping to narrow the critical region of SHFM3; and facilitates an understanding of the mechanisms underlying abnormal limb development and extraskeletal anomalies.