Xeroderma pigmentosum complementation group A (XPA) is a severe form of xeroderma pigmentosum (XP; see this term), a rare photodermatosis predisposing to skin cancers.
It accounts for 25% of all XP cases but its overall prevalence is unknown. It is the most common form of XP in Japan.
XPA shows typical XP manifestations (photosensitivity of skin with burning, freckling, and skin cancers) and is associated with a spectrum of mild to severe neurological anomalies (e.g. cognitive deterioration, dysarthria, balance disturbance, areflexia) and sometimes delay of growth and sexual development.
The disease is due to mutations in the XPA gene (9q22.3), involved in damage verification of the nucleotide excision repair (NER) system.
Transmission is autosomal recessive.
Last update: May 2011