Coloboma of macula - brachydactyly type B or Sorsby syndrome is a malformation syndrome characterized by the combination of bilateral coloboma of macula with horizontal pendular nystagmus and severe visual loss, and brachydactyly type B (see these terms). The hand and feet defects comprise shortening of the middle and terminal phalanges of the second to fifth digits, hypoplastic or absent nails (congenital anonychia; see this term), broad or bifid thumbs and halluces, syndactyly and flexion deformities of the joints of some digits. Coloboma of macula - brachydactyly type B is inherited in a dominant manner.

Short distance from the end of the finger to the most distal interphalangeal crease or the distal interphalangeal joint flexion point. That is, hypoplasia of one or more of the distal phalanx of finger.