Abstract: Objective: To detail the clinical findings in a consanguineous Chinese family,and to identify homeobox D13（HOXD13）gene mutation of the affected individuals in a Chinese synpolydactyly（SPD）kindred.Methods: The genomic DNA was extracted from the peripheral blood samples of SPD family members.With the use of a pair of sepecific primers,exon1 and exon2 of HOXD13 were emplified by polymerase chain reaction（PCR）.All the amplified fragments were electrophoresed on 2% agarose gels,and the purified PCR products of normal and mutant alleles were cloned and sequenced.Results: The kindred including 23 members and 6 get affected.Genomic DNA was extracted from 5 affected family members,a fragment of 291bp was amplified by PCR to cover the imperfect GCG triplet repeat sequence in exon 1 of HOXD13 encoding the 7-residue polyalanine tract,the exon 2 has no such mutation.Conclusion: We first reaveal that HOXD13 encodes additional 7-residue polyalanine expansion in a consanguineous Chinese family which suggest that synpolydactyly may result from polyalanine expansion in HOXD13.