A genetic electrophoretic variant of human hair alpha polypeptides.

The structural proteins of hair were solubilized by reduction of disulfide bonds in 6 M urea at alkaline pH. Following conversion of the proteins to the S-carboxy-methyl derivatives, disc electrophoresis was done in 6 M urea at pH 8.3. In about 5% of the individuals studied, a variation in the normal electrophoretic pattern was observed, and this was true of hair from different body sites. An autosomal dominant mode of inheritance was found in the four families investigated. The variant pattern was not associated with any detectable change in the color, shape, stree-strain characteristics, X-ray diffraction pattern, or amino acid composition of the hair. A similar variant pattern was also observed in nail. The most likely hypothesis is that there is a polymorphism of one of the alpha polypeptides, although a mutation of a rate-determining gene cannot be excluded.