Xeroderma pigmentosum (XP) is a rare but serious inherited disease involving extreme sensitivity to sunlight (photosensitivity), specifically the sun’s ultraviolet (UV) rays. This sensitivity develops during the first few years of life.

Patients with XP typically experience painful and severe sunburns, even after minimal sun exposure. As the disease progresses the skin becomes excessively dry and rough with signs of premature aging.

Signs and symptoms of XP may include:

• Skin atrophy (thinning)
• Irregular dark spots (hyperpigmentation) 
• Growths or tumors

Typically, the eyes of XP patients are also affected and often become irritated, bloodshot and clouded following exposure to UV radiation.

There is no cure for XP and the skin deterioration that occurs with the disease is cumulative and often irreversible. People with this condition often require lifelong protection from sunlight or ultraviolet radiation-emitting agents (e.g., mercury-vapor lamps). XP has severe life-threatening complications that may include:

• Skin cancer
• Cancerous tumors in the eyes and mouth area

Sometimes patients with XP may experience progressive neurological problems, including:

• Developmental (learning) disabilities
• Mental retardation
• Hearing loss that may lead to deafness