Brachydactyly type B

What it is

A rare congenital limb malformation syndrome characterized by hypoplasia or aplasia of the terminal parts of fingers 2 to 5, with complete absence of the fingernails. The thumbs are always intact but frequently show flattening, splitting or duplication of the distal phalanges. Digits on the radial side of the hand are less severely affected than those on the ulnar side. The feet are similarly affected but less severely. Soft tissue syndactyly, symphalangism, carpal and/or tarsal fusions and shortening of metacarpals and/or metatarsals may be present.

Key facts

Prevalence

<1 / 1 000 000

Age of onset

Antenatal

Inheritance

Autosomal dominant

Classified as

Malformation syndrome

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Genes reported in subtypes

Orphanet records these genes on 2 more specific entries under this disorder, not on this entry itself:

A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Cross-references