How XPC gene related to health cause XP .....

Xeroderma Pigmentosum (XP) is caused by mutations in the XPC gene. More than 40 mutations in the XPC gene have been found to cause Xeroderma Pigmentosum. Mutations in this gene are the most common cause of this disorder in the United States and Europe.

Most XPC gene mutations prevent the production of any XPC protein. A loss of this protein keeps cells from repairing DNA damage normally. As a result, abnormalities accumulate in DNA, causing cells to malfunction and eventually to become cancerous or die. These problems with DNA repair cause people with XP to be extremely sensitive to UV rays from sunlight. When UV rays damage genes that control cell growth and division, cells can grow too fast in an uncontrolled way. As a result, people with XP  have a greatly increased risk of developing cancer. These cancers occur most frequently in areas of the body that are exposed to the sun, such as the skin and eyes.

Unlike some of the other forms of Xeroderma Pigmentosum (XP), when the disorder is caused by mutations in the XPC gene it is generally not associated with neurological abnormalities (such as delayed development and hearing loss). It is unclear why some people with XP develop neurological abnormalities and others do not.

Source: www.ghr.nlm.nih.gov