Association between leucocyte group-5a antigen and acute lymphoblastic leukaemia.

Leucocyte group 5 has two dominant alleles (5a and 5b) which segregate independently of the major histocompatibility complex. The group-5 system was studied in a Caucasian population of controls and patients with acute lymphoblastic leukaemia. The 5a gene frequency was 0-09 in 72 controls and 0-38 in 39 patients with acute lymphoblastic leukaemia (p less than 0-001). 15 patients with acute myelogenous leukaemia and 12 patients with aplastic anaemia had 5a and 5b frequencies similar to those seen in the control population. It is concluded that 5a or a closely linked gene is involved in susceptibility to acute lymphoblastic leukaemia.