Xeroderma pigmentosum-Cockayne syndrome complex in two patients: absence of skin tumors despite severe deficiency of DNA excision repair.

Two brothers had a complex combination of two DNA repair disorders: Cockayne syndrome and xeroderma pigmentosum. This rare combination has previously been observed in only two other patients. The clinical signs shared by these two brothers and the two other previously described patients include severe sun sensitivity, freckling, diminished stature, hearing and movement impairment, and neurologic degeneration. Although defective UV-induced unscheduled DNA synthesis has been demonstrated (5% of normal), no skin cancers have appeared in these 38- and 41-year-old brothers, whereas skin cancers developed at a relatively early age in the two previously described patients who also had defective UV-induced unscheduled DNA synthesis.