IDENTIFICATION OF A NEW POLYMORPHISM IN THE HUMAN PROTEOLIPID PROTEINGENE

A polymorphism in the gene for proteolipid protein has been identified , using amplification by the polymerase chain reaction, restriction en zyme digestion, and fragment separation by polyacrylamide gel electrop horesis. The polymorphism is located in the transcribed 3'-untranslate d region, a region with potential regulatory signals. The mutation con sists of a single base pair insertion into a Hae III restriction site, producing a larger rare fragment of 409 bp as compared with the more frequent 325 bp fragment. The gene for proteolipid protein is on the X chromosome; thus the males are hemizygous for the rare allele and the females are heterozygous carriers. The polymorphism occurs with a fre quency of 0.046 in a population of European origin and also has a rare frequency in multiple sclerosis patients.