label: Aplasia/Hypoplasia of the 1st metacarpal
label_lc: aplasia/hypoplasia of the 1st metacarpal
description: "Aplasia or Hypoplasia affecting the 1st metacarpal. In contrast to the metacarpals 2-5, the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the digits 2-5 (whereas the proximal phalanx of the thumb is equivalent to the middle phalanges of the other digits)."