DNA testing for haemochromatosis: diagnostic, predictive and screening implications.

Since 1996, the identification of the HFE gene has enabled DNA testing for hereditary haemochromatosis (HH). The range of DNA testing available includes: (1) diagnostic, (2) predictive (also called presymptomatic testing) and (3) screening. Access to DNA testing has been facilitated by an Australian Medicare rebate, the first available for genetic disorders. Despite the availability of HFE DNA testing in HH, it remains necessary to interpret results in the context of the clinical picture. Traditional markers based on phenotype (transferrin ferritinsaturation, and liver biopsy) are still required in some circumstances. We report our experience with HFE DNA testing using a semi-automated approach, which allows multiplexing for the two common mutations (C282Y and H63D). Screening a cohort of beta-thalassaemia major and sickle cell anaemia patients of predominantly Mediterranean origin showed that these individuals do not have the common C282Y mutation. This excluded C282Y as a factor in the pathogenesis of iron overload in these haemoglobinopathies. It also showed that the C282Y mutation is of limited value when investigating HH in certain ethnic groups. An Australian family studied illustrated the relative contribution of C282Y and H63D in iron overload. A recently reported third mutation (S65C) in the HFE gene was detected in a low frequency in the populations tested.