Brachydactyly type D
Brachydactyly type D, also known as murderer's thumb, stubbed thumb, spoon thumb, power thumb or short thumb, is a genetic trait recognised by a thumb being relatively short and round with an accompanying wider nail bed. The distal phalanx of such thumbs is approximately two-thirds the length of full-length thumbs. It is the most common type of shortness of digits, affecting approximately 2% of the population. It is associated with the HOXD13 gene, located on chromosome 2q31.1.
Signs and symptoms
type D is a skeletal condition that exhibits a “partial fusion or premature closing of the epiphysis with the distal phalanx of the thumb,” according to Goodman et alia. J.K. Breitenbecher found that the distal phalanges of short thumbs were one-half the length of full-length thumbs, while R.M. Stecher claimed that it is approximately two-thirds. The condition may be unilateral or bilateral.Genetics
type D is a genetic trait. It exhibits autosomal dominance and is commonly developed or inherited independently of other hereditary traits. The condition is associated with the HOXD13 gene, which is central in digital formation and growth.Various other studies supported an autosomal dominant pattern with reduced penetrance.