True about hemochromatosis
Correct Answer: Mutation of C282Y
Description: Heridetary hemochromatosis The disease is caused by increased absorption of dietary iron and is inherited as an autosomal recessive trait. Approximately 90% of patients are homozygous for a single point mutation resulting in a cysteine to tyrosine substitution at position 282 (C282Y) in the HFE protein, which has structural and functional similarity to the HLA proteins. The mechanisms by which HFE regulates iron absorption are unclear. It is believed, however, that HFE normally interacts with the transferrin receptor in the basolateral membrane of intestinal epithelial cells. In HHC, it is thought that the lack of functional HFE causes a defect in uptake of transferrin-associated iron, leading to up-regulation of enterocyte iron-specific divalent metal transpoers and excessive iron absorption. A histidine-to-aspaic acid mutation at position 63 (H63D) in HFE causes a less severe form of haemochromatosis that is most commonly found in patients who are compound heterozygotes also carrying a C282Y mutated allele. Fewer than 50% of C282Y homozygotes will develop clinical features of haemochromatosis; therefore other factors must also be impoant. HHC may promote accelerated liver disease in patients with alcohol excess or hepatitis C infection. Iron loss in menstruation and pregnancy can delay the onset of HHC in females. Ref Davidspns 23e p895
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