genetics
Last reviewed 08/2022
Mutation in the HFE gene located on chromosome 6 is the principle gene defect that increases the risk of developing haemochromatosis
- this mutation causes the substitution of tyrosine for cysteine at amino acid position 282 of the protein product (C282Y)
- account for 80%-85% of typical patients with HH
- two more mutations have been identified - aspartate is substituted for histidine at amino acid position 63 (H63D) and cysteine is substituted for serine at amino acid position 65 (S65C)
- are not generally associated with iron loading unless occurring as a compound heterozygote (C282Y/H63D or C282Y/ S65C) (1,2)
Other inherited forms known as non HFE related hereditary hemachromatosis (HH) encompasses all genetic hemachromatosis unrelated to HFE mutations.
- transferrin receptor 2 (TfR2)-associated haemochromatosis
- also called “type 3 haemochromatosis”
- caused by mutations in the genes for transferrin receptor 2 (TfR2)
- autosomal recessive form which is clinically similar to HFE related HH
- may present early in life.
- juvenile haemochromatosis
- also known as “type 2 haemochromatosis”
- mutations in two different genes results in two forms of juvenile HH
- type 2A - mutation in the hemojuvelin (HJV) gene on chromosome 1q – most common form
- type 2B - mutations in the hepcidin gene (HAMP)
- mutations in the genes for ferroportin (SLC40A1)
- improperly called “type 4 haemochromatosis”
- inherited in a dominant fashion (1,2)
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