XERODERMA PIGMENTOSUM
Xeroderma pigmentosa, or XP, is an autosomal recessive genetic disorder of DNA repair in which the ability to repair damage caused by ultraviolet (UV) light is deficient. This disorder leads to multiple basal cell carcinomas (basaliomas) and other skin malignancies at a young age. In severe cases, it is necessary to avoid sunlight completely. The two most common causes of death for XP victims are metastatic malignant melanoma and squamous cell carcinoma. XP is about six times more common in Japanese people than in other groups.
The most common defect in xeroderma pigmentosum is an autosomal recessive genetic defect whereby nucleotide excision repair (NER) enzymes are mutated, leading to a reduction in or elimination of NER. Unrepaired damage can lead to mutations, altering the information of the DNA in individual cells. If mutations affect important genes, such as tumour suppressor genes (e.g. p53) or proto oncogenes, then this disorder may lead to cancer. Patients exhibit elevated risk of developing cancer, such as basal cell carcinoma.
