16 May 2005
Hereditary hemochromatosis (HHC) is a recessive genetic disorder in which inappropriately high levels of iron are absorbed in the gut, causing excessive iron storage in organs such as the liver. Without treatment, hepatic cirrhosis and other serious conditions including diabetes, cardiomyopathy and arthritis may occur from the age of around 40 onwards. Routine venesection (blood-letting) to maintain appropriate serum iron levels is a simple yet effective means by which to prevent these complications.The majority of people with hereditary haemochromatosis are homozygous for the C282Y mutation in the HFE (haemochromatosis) gene. In the UK, C282Y homozygotes comprise over 90% of affected individuals, and 1 in 150 of the general population; the disease shows relatively low penetrance, and many homozygotes never develop clinical symptoms. Early diagnosis and pre-symptomatic treatment can prevent all potential complications of hemochromatosis, but there is no way of identifying which individuals with the mutation are likely to develop symptoms. Population screening for HHC has been proposed in the UK, due to the high prevalence of the mutant allele coupled with the low cost and high efficacy of early diagnosis and treatment compared with that for late stage diagnosis. However, opponents cite the low penetrance and unpredictablity of the clinical genotype as arguments against population based screening.
A publication in the Lancet reports on an assessment of the uptake of screening by first-degree relatives of two groups, C282Y homozygotes identified by genetic screening of blood donors, and patients presenting clinically with haemochromatosis [McCune et al., 2003, Lancet 362, 1897-98]. They found that whilst 53% of relatives of haemochromatosis patients had previously been screened, only 24% of the relatives of non-symptomatic blood donors had been tested. The authors conclude that the absence of a relative affected by clinically apparent haemochromatosis apparently reduced motivation for relatives to avail themselves of screening, despite the provision of information about the disease and the risk to family members. They note that: