Brachydactyly type A1 (BDA1) is a congenital malformation characterized by apparent shortness (or absence) of the middle phalanges of all digits, and occasional fusion with the terminal phalanges.Last update: May 2008
Only a few pedigrees have been reported in the literature.
The proximal phalanges of the thumbs and big toes are short. BDA1 patients tend to be of short stature in adulthood.
BDA1 may be caused by mutations in the Indian hedgehog gene (IHH) located on chromosome 2q35-36. Another locus for this phenotype has been identified on chromosome 5p13.3-p13.2.
BDA1 is inherited as an autosomal dominant trait.