Genetic factors linked to the HLA system conferring increased susceptibility to acute lymphoblastic leukemia in children

Inheritance of HLA antigens in 55 families of patients with ALL was analyzed. Significantly increased sharing of DR antigens was observed among the parents of the affected children (p = 0.003). A similar increase was noted in the sharing of HLA-B antigens (p = 0.02). The observed number of DR homozygotes among the patients was twice the expected value in families where the parents shared a B and a DR antigen. Segregation analysis of the shared antigens disclosed significant prevalence of heterozygotes among the healthy siblings, which suggested the occurrence of gametic selection in such families. This study indicates that mating of certain shared alleles of the HLA system (especially of the DR locus) is associated with a risk for the offspring to develop ALL in childhood. Restricted heterogeneity of the parental HLA gene pool favours the expression of linked recessive genes and, presumably, of those involved in susceptibility to ALL.