Exome sequencing identifies a novel nonsense mutation of HOXD13 in a Chinese family with synpolydactyly.

Synpolydactyly (SPD) is an autosomal dominant limb malformation with a distinctive combination of syndactyly and polydactyly. SPD is clinically heterogeneous and could be genetically classified into three types. The clinical phenotype of SPD is complicated by its variable expressivity. In the present study, whole exome sequencing (WES) was used to identify the affected gene(s) in a Chinese family with atypical SPD phenotype. Our results showed that a novel heterogenous nonsense mutation (c.556C > T, p.R186X) in HOXD13 was associated with this SPD case. Due to variable expressivity, the diagnosis of a clinical heterogenous disease such as SPD is usually difficult. Our results also suggested that WES is an efficient tool to assist with these diagnoses.