Group-specific component: evidence for two subtypes of the Gc1 gene.

A new method based on isofocusing electrophoresis in the study of the Gc (group-specific component) polymorphism, revealed differing electrophoretic patterns. These patterns can be explained by the existence of two codominant Gc1 subtypes. This hypothesis is in accordance with several family studies. These subtypes are called Gc1F and Gc1S. Eight hundred samples were analyzed, including three different populations: Caucasoid (a western Pyrenean valley), African (Pygmy Bi-Aka), and AMerindian (Quechua-Aymara, from Bolivia). These two subtype phenotypes cannot be explored with the usual technique. They were present in each population sample studied.