Dominant mutations in human TBX5 cause Holt–Oram syndrome (HOS, OMIM:142900), an autosomal dominant disorder characterized by upper limb malformations, congenital heart defects, and CCS abnormalities (Basson et al., 1997; Li et al., 1997; Basson et al., 1994). This evidence concerns the gene TBX5 and Holt-Oram syndrome.