Distribution of HLA Antigens

Abstract

A race is considered to be a subdivision of a species formed by a group of individuals sharing common biological characteristics that distinguish them from other groups. Racial variations may have developed from relative isolation in different environments which allows drift and natural selection to bring about divergence, which may have followed emigration of groups to distant areas. Therefore, we would expect differing races to have varying gene frequencies. Analysis of gene frequency can be used to determine evolutionary relationships between populations by the calculation of genetic distance. Cavalli-Sforza and Edward constructed an evolutionary tree based on the blood-group frequencies of fifteen groups; three groups derived from each continent (1). Their evolutionary tree projected on a world map fits remarkably well with the probable routes of human migration. The more polymorphism used in the calculation of genetic distance, the more accurate the estimates of evolutionary relationship. The HLA system, which is highly polymorphic, can be used to further our knowledge of evolutionary relationships.