Final answer:
The total absence of pigmentation in hair and skin is called albinism, a genetic disorder due to a defect in melanocytes preventing melanin production, leading to increased sensitivity to UV radiation and vision issues.
Step-by-step explanation:
The total lack of pigmentation in the hair and skin is called albinism. This genetic disorder is characterized by a complete or partial absence of melanin, which is the pigment responsible for coloring the skin, hair, and eyes. Individuals with albinism experience significantly paler skin and hair, and they require more protection from ultraviolet (UV) radiation as they are more susceptible to sunburns and skin cancer.
Albinism is caused by a defect in the melanocytes, which are cells responsible for melanin production. People with albinism also tend to have vision problems and light sensitivity due to the lack of pigmentation in the retinal wall. Treatment for this disorder focuses on symptom management, such as limiting exposure to UV light.
Conditions like vitiligo also affect skin pigmentation, but contrary to albinism which is uniform depigmentation, vitiligo causes depigmentation in patches due to an autoimmune reaction that causes melanocytes in certain areas to lose their ability to produce melanin.