The “Thompson” Specificity and the HL-A Human Leukocyte System

SummaryPopulation and family studies of the Thompson specificity and four factors of the first sublocus of the HL-A main human leukocyte system are described. The Thompson specificity is strongly allelic or pseudoallelic to the other factors of the sublocus. At the same time, evidence of crossover between Thompson and HL-A has been found in 3 of 7 families studied to date. Taken together, population and family data suggest the possibility that the Thompson factor is the expression of gene interaction or epistasis involving the HL-A and some other system.