Abstract

Mutation analysis of a Chinese pedigree with triphalangeal thumb-polysyndactyly syndrome

Triphalangeal thumb-polysyndactyly syndrome (TPTPS) is an autosomal dominant limb disorder with triphalangeal thumbs, polysyndactyly, and syndactyly. In this study, we describe a four-generation Han Chinese family with eight affected members. Haplotype analysis, Affymetrix SNP 6.0 arrays, qPCR, and gap-PCR were performed. Haplotyping results linked the disease-causing region to the 7q36 region that includes the zone of polarizing activity-regulatory sequence. A 442-kb duplication was found on chromosome 7 that co-segregated with the disease phenotype. The extent of the duplication was determined by qPCR, and the breakpoints were identified by gap-PCR and direct sequencing. This mutation was not detected in normal members in the same family. Our data therefore suggest that this novel microduplication, between 155,913,768 and 156,355,553 bp on chromosome 7, could be considered the cause of TPTPS in this kindred.

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