We just came to know that Xeroderma Pigmentosum (XP) is a ‘autosomal recessive’ disorder. But the genetic disorder is caused due to a faulty DNA Repair Mechanism of the skin.
Ultraviolet Ray (UV Rays) from the Sum, damages the DNA of the skin cells. Normally the body repairs this damage through the process called ‘Nucleotide Excision Repair (NER)’ (we will discuss the process later). But a defect in NER results in an inefficient DNA repair mechanism in XP. As the cells are unable to repair it, the DNA remains damaged which leads to cells death making the skin very thin and patchy (splotchy pigmentation) and develop carcinoma (cancerous) cells.
XP also causes spidery blood vessels in the skin (telangiectasia) and skin cancer, occurs before the child became 5 yrs old.