Xeroderma pigmentosum

Xeroderma pigmentosum is a genetic disorder marked by a severely decreased ability to repair DNA damage such as that caused by ultraviolet light. It results from mutations in at least nine genes involved in nucleotide excision repair, preventing normal correction of UV induced DNA damage in skin cells and allowing malfunctioning cells to progress toward cancer. Affected people develop severe sunburns from minimal sun exposure along with excessive freckling, dry skin, pigmentation changes and eye sensitivity, and face a skin cancer risk roughly a thousand times higher than the unaffected population; some also develop neurological problems such as hearing loss, poor coordination and seizures. The condition is inherited in an autosomal recessive pattern, requiring a mutated gene copy from each parent, affects males and females equally, and has a worldwide prevalence of roughly one in 100,000 people, varying significantly by region.