Xeroderma pigmentosum is an autosomally recessive inherited disease, which means that you have inherited two recessive xeroderma pigmentosum genes (one from each parent). If your parents are only carriers of the xeroderma pigmentosum trait (each have one xeroderma pigmentosum gene and one normal gene), they will not show signs or symptoms of the disease.
Essentially, the signs and symptoms of xeroderma pigmentosum are a result of an impaired DNA repair system. In people who do not have xeroderma pigmentosum, cell damage from UV light is mended by the DNA repair system. However, people with xeroderma pigmentosum have a defect in this repair system and any damaged cells from UV light remain unrepaired, leading to cancerous cells or cell death.
