... MelanonychiaWhen the nail plate has a black or brown stripe due to a buildup of melanin (the pigment that gives your skin its color), this is called melanonychia. This dark stripe often runs up and down, known as longitudinal melanonychia. ...
4 Ways HIV May Affect Your Nails
... MelanonychiaWhen the nail plate has a black or brown stripe due to a buildup of melanin (the pigment that gives your skin its color), this is called melanonychia. This dark stripe often runs up and down, known as longitudinal melanonychia. ...
... If you have darker skin, the melanin pigment in your skin may block the sun’s rays and interfere with making vitamin D from sun exposure. ...