A teenager has just been told by the dermatologist that he is high risk for developing skin cancer since he has natural red hair and fair skin. The physiology behind this statement may be due to the:

Question

A) Oversecretion of eumelanin, a brown-black pigment that causes tans
B) Enhanced photoreactivity of pheomalanin, as compared to eumelanin
C) Lack of pheomelanin pigmentation, which protects against skin cancer formation
D) Increased susceptibility to photosensitivity due to oversecretion of melanin

Answer 1

Ans: B
Feedback:
There are two major forms of melanin: eumelanin and pheomelanin. Exposure to the sun's ultraviolet rays increases the production of eumelanin, a brownish black pigment, which causes tanning to occur. An enhanced photoreactivity of the red melanin, pheomelanin, compared to the black melanin, eumelanin, is commonly invoked to explain why fair-skinned individuals are more susceptible to skin cancers. The primary function of such melanin is to protect the skin by absorbing and scattering harmful ultraviolet rays, which are implicated in skin cancers. Localized concentrations of eumelanin are responsible for the formation of freckles and moles. This does not mean that they will develop skin cancer. Pheomelanin, a reddish yellow pigment, provides color to the body when it is concentrated, primarily in the lips, nipples, glans penis, and vaginal areas. Photosensitivity refers to abnormal sensitivity (not reactivity) of the skin to ultraviolet light, usually following exposure to certain oral or topical drugs or to other sensitizing chemicals and resulting in accelerated burning and blistering of the skin. Both types of melanin are found in hair, particularly red hair. It has been suggested that the reason fair-haired individuals are more susceptible to skin cancers may be due to the enhanced photoreactivity of pheomelanin, as compared to eumelanin.