Xeroderma Pigmentosum, or XP, is a genetic disorder that affects the ability of skin cells to repair the damage done by ultraviolet (UV) light. This means that UV light can easily cause burns, cancers, and other skin malignancies. In extreme cases, those suffering from XP have to avoid exposure to even the smallest amount of sunlight, and even be wary of artificial sources of UV light— such as neon tubes and some energy-saving fluorescent lamps. The necessity of complete avoidance of sunlight has led to individuals with the disease being given the nickname in French of Les Enfants de la Lune (Children...