SOUTHERN BLOOD CLUB SYMPOSIUM - AN UPDATE ON SELECTED ASPECTS OF HEMOCHROMATOSIS

Genetic epidemiology studies have indicated that hereditary hemochromatosis (HH) occurs in caucasians with a frequency of 3 to 13 per thousand. Clinical recognition however occurs far less frequently. The disparity is best resolved by defining HH as homozygosity for the HLA-linked hemochromatosis allele, regardless of the total body iron burden. Variability of clinical expression is explained in part by physiologic iron loss in women but variability in males may be due to environmental factors, gene-gene interactions or polymorphisms in mutated hemochromatosis alleles. Although clinical variability is great, the laboratory phenotype of HH is fairly constant and is marked by elevation of the transferrin saturation. The elevated transferrin saturation occurs early in life, before organ iron loading occurs and can be used as a screening tool to detect HH before organ damage occurs. Cloning and characterizing the HH gene, which is located within 1 centimorgan of the HLA-A locus should resolve some of the issues concerning clinical variability.