Linear chains of amino acids that singly or in multiples of two or more form into proteins. Chains of just two amino acids are called, chains of three are, and any more are polypeptides.inear chains of amino acids that singly or in multiples of two or more form into proteins. Chains of just two amino acids are called, chains of three are, and any more are polypeptides.
Vitiligo: A Common Cause of Loss of Skin Pigment. Melanin is the pigment that gives the skin its characteristic color. Vitiligo is caused by a loss of pigment in the skin, due to destruction of pigment-forming cells known as melanocytes. Although vitiligo affects all races equally, it is more noticeable in dark-skinned people. Vitiligo can cause cosmetic problems.
Vitiligo facts*. 1  Vitiligo is a disease in which the pigment cells of the skin, melanocytes, are destroyed in certain areas. 2  Vitiligo results in depigmented, or white, patches of skin in any location on the body.  Vitiligo can be focal and localized to one area, or it may affect several different areas on the body.