Genetics

  1. The gene involved in HH is called the HFE gene.
  2. Mutations in the HFE gene can lead to impaired regulation of iron storage and are believed to be the
    most common cause of HH.
  3. Frequencies of HFE genotypes in the Australian population are shown in Table 1.
  4. About 90% of people of Northern European ancestry with symptoms of HH have the C282Y mutation in both copies of their HFE gene - homozygotes (see Contacts, support and testing for an explanation of terminology).
  5. About 2% of people with HH have a C282Y gene mutation in one of their copies of the HFE gene, and the H63D gene mutation in their other copy (compound heterozygotes).
  6. Compound heterozygotes have inherited one copy of the C282Y gene mutation from one parent and one copy of the H63D gene mutation from the other parent.
  7. HH follows an autosomal recessive pattern of inheritance.
  8. Therefore there is often no family history of the condition, or affected family members may appear to be scattered amongst or within generations.
  9. Where both parents are heterozygous (carriers for a mutation in the HFE gene), there is a 25% chance
    that each of their children will inherit a gene mutation in both copies of their HFE gene, and be genetically predisposed to HH.
  10. If only one parent is a carrier for a mutation in the HFE gene, there is a 50% chance that each of their children will be an HFE mutation carrier.
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Table 1

Frequencies of HFE genotypes in the Australian population

Table 1

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Prevalence

  1. More common in people of Northern European backgrounds:
  2. Affects about 1 in 250 people of Northern European background
  3. Approximately 1 in 8 people with this same ancestry are carriers for a mutation for haemochromatosis (heterozygotes)
  4. Uncommon in Asian and African populations.
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