Pigmentary anomalies in ataxia-telangiectasia: a clue to diagnosis and an example of twin spotting

A 6-year-old girl with consanguineous parents presented with a history of p rogressive ataxia and patchy, segmental pigmentary changes, some reminiscen t of Blaschko's lines. There was no evidence of oculocutaneous telangiectas es or signs of immunodeficiency. A clinical diagnosis of ataxia-telangiecta sia (AT) was suggested and confirmed by the presence of a low serum IgA, ra ised alpha -fetoprotein and chromosomal rearrangements of chromosomes 7 and 14. This case of AT is unique for having hypopigmentation and hyperpigment ed patches adjacent to each other, which is a feature that has been describ ed as 'cutis tricolor', and is unusual for having pigmentary skin changes, some in the lines of Blaschko without telangiectases. Clinicians should be aware that a diagnosis of AT may be made in the absence of telangiectases.