Macrodactyly

A number sign (#) is used with this entry because of evidence that macrodactyly can be caused by somatic mutation in the PIK3CA (171834) gene on chromosome 3q26.

Description

Macrodactyly is a congenital anomaly characterized by fibrofatty tissue enlargement and bony overgrowth in affected digits with resultant loss of function. Macrodactyly affects a 'nerve territory,' and the individual peripheral nerve is both enlarged and elongated (summary by Rios et al., 2013).

Clinical Features

One or 2 fingers are grotesquely enlarged. Barsky (1967) and others found no report of familial occurrence. Lacombe and Battin (1996) described 2 children diagnosed at birth as having isolated macrodactyly. Follow-up examination showed development of hemihypertrophy and other findings suggesting Proteus syndrome (176920).

Molecular Genetics

In 6 patients with macrodactyly, Rios et al. (2013) identified 4 different somatic mutations (e.g., 171834.0022) in the PIK3CA gene in affected tissue.