[Siblings with xeroderma pigmentosum group A showing mild cutaneous and various neurological manifestations]

We report siblings with xeroderma pigmentosum group A (XP-A) showing mild cutaneous and late-onset severe neurological manifestations. The elder brother first noticed unstability in walking at 16 years of age. Subsequently slowly progressive mental deterioration developed with cerebellar ataxia, spasticity, sensory disturbance, urinary dysfunction and vocal cord paralysis. His younger sister presented with dysarthria at 18 years of age. She showed manifestations similar to her brother's. Both of them suffered from sensitivity to the sun but no malignant skin tumor. They were diagnosed as XP-A by the measurement of unscheduled DNA synthesis and complementation analysis. Gene analyses revealed compound heterozygote for G-->C substitution at the 3' splicing acceptor site of intron 3 and insertion of 4 bases in exon 6 of XPA gene. It is suggested that transcription-coupled repair is dominantly affected with relative sparing of global genome repair in these siblings.