Zhao et al. (2007) described a Han Chinese family in which 23 affected individuals in 6 generations exhibited a complex brachydactyly-syndactyly syndrome. Digital photographs and radiographs were taken for 16 and 13 of them, respectively. Most of the ... Zhao et al. (2007) described a Han Chinese family in which 23 affected individuals in 6 generations exhibited a complex brachydactyly-syndactyly syndrome. Digital photographs and radiographs were taken for 16 and 13 of them, respectively. Most of the patients exhibited generalized shortening of the hands and feet, 11 displayed broad and short distal phalanges of the thumbs, and 14 had mild cutaneous syndactyly of toes 2 and 3. Radiographs revealed a constant feature in all 13 patients: absence of middle phalanges of toes 2 through 5 and very marked short middle phalanges of the fifth finger. Combined shortening of the middle phalanges was noted, with the effect that the second and fifth fingers were most severely affected. In many cases the shortened middle phalanges were fused with the distal ones. Shortening of metacarpal 5, either alone or in combination with metatarsal 5 and/or other metacarpals/metatarsals, and short proximal phalanges of toes 1, 3, and 4 were noted in several patients. Other common limb anomalies included broad first metatarsals and hallux phalanges, often associated with hallux valgus. The proband also had small spurs of bone between the first and second metatarsals. These limb phenotypes overlapped those of brachydactyly types A4 (BDA4; 112800), D (113200), and E (113300), and syndactyly type I (185900).
In the large Han Chinese family with brachydactyly-syndactyly described by them, Zhao et al. (2007) found deletion of 21 basepairs in the HOXD13 gene (142989.0010) in affected members. The deletion was located in the imperfect GCN (where N ... In the large Han Chinese family with brachydactyly-syndactyly described by them, Zhao et al. (2007) found deletion of 21 basepairs in the HOXD13 gene (142989.0010) in affected members. The deletion was located in the imperfect GCN (where N denotes A-C, G, or T) triplet-containing exon 1 of HOXD13, and resulted in a polyalanine contraction of 7 residues. The site and length of the polyalanine tract in HOXD13, like that in the paralogous HOXA13 (142959), are highly conserved among mammals.