Genetic haemochromatosis comes in several variants, depending upon genetic mutation. Each has its own characteristics.
HFE variants (common)
The most common type, known as HFE (or type 1) genetic haemochromatosis is present in around 1 in 150 people in England & Wales, 1 in 113 people in Scotland and around 1 in 10 people in Northern Ireland. HFE variants are not rare, but rarely diagnosed.:
Non-HFE Variants (rare)
Over the years, other non-HFE causes of iron overload have been isolated. These are known as "non-HFE" variants as they are caused by genetic mutations associated with genes other than the HFE gene. These variants are also known as types 2, 3 and 4. Type 4 is also sometimes called Ferroportin Disease. The prevalence of non-HFE variants is under-studied but thought to be "rare" (affecting 1 in 30,000 people or fewer).
Overall, it is thought that around 160 genetic mutations can cause or contribute to iron overload, to varying degrees. There are also "molecularly undefined" variants, for which the genetic cause is unknown or unexplored, but where iron overload has been demonstrated. These variants are rare.
There may also be other genetic mutations which predispose people to iron overload. As medical research and our understanding of the human genome progress, these may become distinctly identified. In the meantime, our charity works to support anyone affected by genetic haemochromatosis, whatever its cause.
There are several known types of genetic haemochromatosis.
Getting Tested for Genetic Haemochromatosis
In the UK, the NHS typically only tests for HFE (type 1) mutations in C282Y and H63D. This is known as a R95 test. The NHS Genomic Test Directory makes provision for people exhibiting symptoms of iron overload who have been tested for Type 1, to receive further testing for non-HFE causes of haemochromatosis. This is known as a R96 test.
Our charity provides a postal testing service for genetic haemochromatosis, for HFE and non-HFE variants. For further details, read more about genetic testing.
Type 2 haemochromatosis is known as a juvenile-onset disorder because symptoms often begin in childhood. Read more
This guide explains the rarer form of non-HFE genetic haemochromatosis, also known as type 3 or TFR2-related GH. Read more
This guide explains the rarer form of non-HFE genetic haemochromatosis, called Ferroportin Disease. Read more