HLA-A and HLA-B antigens were determined in 16 unrelated subjects orginating from Veneto affected by idiopathic haemochromatosis (IH). HLA-A3 was found in 13/16 patients vs. 300/1,348 controls (p less than 0.00005). Prevalences of A3,B35 haplotype were 0.4375 in patients vs. 0.0816 in controls (p less than 0.0005). Linkage disequilibrium analysis proved the existence of a positive third-order linkage disequilibrium among IH, HLA-A3 and HLA-B35 alleles. Our data confirm the close association of IH and HLA-A3 and prove the peculiar association of the disease with A3,B35 haplotype in north-eastern regions of Italy. The positive third-order linkage disequilibrium suggests a remote event (mutation, recombination or immigration) as origin for IH and A3,B35 association.
