A short thumb is known as Brachydactyly type D, and also known as stub thumb and commonly referred to as clubbed thumb. A brachydactyly is a condition clinically recognised by a thumb being relatively short and round with an accompanying wide nail bed. The distal phalanx of affected thumbs is approximately two-thirds the length of full-length thumbs. It is a type of brachydactyly, or shortness of digits, and is associated with the HOXD13 gene.

Brachydactyly is a potentially inherited condition which is associated with fingers or toes that are disproportionately short compared to the hand or the foot. The diagnosis is used to describe a series of Mendelian diseases characterized by distinct patterns of shortened digits (brachydactyly types A-E).

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