Brachydactyly type A2

What it is

A rare, congenital limb malformation characterized by shortening (hypoplasia or aplasia) of the middle phalanges of the index finger and, sometimes, of the fifth finger. On radiographs, the middle phalanx of the index fingers often appear triangular and in severely affected cases, the index finger is curved radially. The lower limb phenotype is generally milder.

Key facts

Prevalence

<1 / 1 000 000 (Europe)

Age of onset

Infancy, Neonatal

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

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