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Several Genetic Mutations May Cause Hemochromatosis
WESTPORT, Aug 30 (Reuters Health) - While a gene responsible for hereditary hemochromatosis (HFE) has been identified, results of a study in the September 2nd issue of The New England Journal of Medicine show that the clinical condition can occur in those who do not have mutations in this gene.
In another study in the issue, Australian researchers report that a substantial proportion of people who have the HFE gene mutation do not have clinical features of hemochromatosis.
The former finding comes from Dr. Antonello Pietrangelo, of the University of Modena in Italy, and colleagues. They report on a study of one patient with hemochromatosis and 52 of his relatives. Fifteen of them had transferrin saturation above 50%, abnormal ferritin levels, or both.
However, "[n]one of the 15 family members with abnormal iron values had the C282Y mutation of the HFE gene," the researchers write. Five family members with iron overload did have a heterozygous H63D mutation in the gene, but so did five other family members with normal iron levels, they note.
"The iron-overload disease in this family was not due to the presence of the C2827 mutation of the HFE gene," Dr. Pietrangelo's team concludes. "[O]ur study indicates the existence of one or more distinct genetic diseases that cause a type of adult hereditary iron overload other than that associated with the HFE gene," they write.
In the other study, Dr. John K. Olynyk, of the University of Western Australia in Fremantle, and colleagues genotyped some 3,000 people, about one-third of the town of Busselton, Australia. In this sample, 16 people--0.5% of the population--was homozygous for the C282Y mutation in the HFE gene, they report.
Of these 16 subjects, however, just 8 displayed clinical features of hemochromatosis, according to Dr. Olynyk's team. Four had been previously diagnosed with hemochromatosis; of the 12 who had not, 7 had high serum ferritin levels which increased further in 6 during follow-up.
"Not all subjects who have the genes for the disease will develop health consequences from iron overload," Dr. Olynyk told Reuters Health. "About 70% of patients will have progressive iron overload," he noted.
"I think there should be a national screening policy for this disease in countries with high prevalence rates--the United States, Australia, the United Kingdom and Nordic communities," Dr. Olynyk told Reuters Health. "Most life threatening sequelae can be completely prevented by early diagnosis and treatment," he noted.
In an editorial that accompanies the study, Dr. Anthony S. Tavill, of Case Western Reserve University School of Medicine in Cleveland, says, "The message is clear: most persons who are homozygous for the C282Y mutation have iron overload, and this mutation can be detected reliably by measuring transferrin saturation."
N Engl J Med 1999;341:718-732,755-757.
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