HLA determinants in idiopathic haemochromatosis.

HLA-antigens were determined in 21 unrelated patients with idiopathic haemochromatosis and in eight siblings and 13 children of the probands. The prevalences of HLA-A3, B7, and B14 in patients compared to 1967 healthy control subjects were: A3, 76.2% versus 26.9% (p less than 0.0001); B7, 57.1% versus 26.8 (p less than 0.001); B14, 9.5% versus 4.5% (n.s.); A3 and B7, 42.9% versus 12.2% (p less than 0.0001); A3 and B14, 9.5% versus 1.4% (p less than 0.001). Siblings (n = 3) that were HLA-identical with the proband were considered to be homozygotes for the haemochromatosis allele and presented with preclinical haemochromatosis. Siblings and children (n = 17) having only one HLA-haplotype in common with the proband were considered to be heterozygotes. Biochemical markers for haemochromatosis (transferrin saturation and serum ferritin) were higher in homozygous than in heterozygous subjects (p less than 0.0001). The results confirm the association between the HLA-A and B loci and the haemochromatosis gene. HLA-typing is a valuable tool in the identification of the haemochromatosis genotype in a family, and it is an adjunct to the biochemical screening procedure in relatives of patients with this iron overload disorder.