Genetic Haemochromatosis : An Overview

GH is the most common genetic disorder amongst Caucasians worldwide, especially Northern Europeans of Celtic and Nordic descent. GH causes the body to absorb excessive iron from the diet leading to increased iron deposits within the body. If left untreated, can cause systemic iron overload in some patients. Over time this iron overload can cause inflammation and damage to multiple organs with the potential to lead to heart disease, arthritis, diabetes, and cirrhosis of the liver. Therefore, diagnosing people at an early stage is critical.

In 2019, a study on the UK Biobank estimated that approximately 380,000 people are affected by GH in the UK (Melzer & the Exeter Research Group, 2019) making this a common disorder. In the UK, as many as 1 in 150 people in England & Wales, or 1 in 113 people in Scotland &  1in 10 in Northern Ireland (image 1) are affected by the condition, but most are unaware that they have it. However, data gathered by HUK from NHS Trusts, discovered less than 20,700 people in the UK are currently being treated (Mortimore & McClements, 2020) highlighting that this is an underdiagnosed condition.

GH is also known by other names such as hereditary haemochromatosis, familial haemochromatosis and bronze diabetes. However, for the purpose of this module it will be referred to as GH.

The Role of Iron In The Body

Iron is an essential element in the body. It helps transport oxygen around the body, aids DNA synthesis and is an essential component in red cell production.

In genetic haemochromatosis the iron regulation mechanism in the gut that controls the amount of iron we absorb is faulty. Consequently, the body absorbs a greater proportion of the iron ingested, compared to someone without the condition. As the body is not able to excrete the iron, any that it has left over has to also be stored which causes increased build-up of iron deposits around the body

We absorb iron through our duodenum and the amount of iron absorbed from our diet is regulated.  We typically eat 10 – 15mg iron a day however we only absorb about 1-2 mg a day as that’s what the body needs.   

However, too much iron (especially over prolonged periods of time) can be harmful.

Unbound iron is toxic so once absorbed it is bound to a protein called transferrin which safely carries it around the body to do its various functions.  The body cannot naturally excrete iron (although a small amount is lost by desquamation of skin cells and any blood loss such as menstruation).  Any excess iron is then stored in a protein called ferritin, in various parts of the body ready for use if needed.  We all have and need a certain level of iron stores.  These stores can be measured through assessing serum ferritin levels. 

Learning points

• GH is a common genetic condition which is underdiagnosed

• Over time, if left untreated the excess iron is deposited throughout the body which can lead to life-threatening complications of cirrhosis, cardiomyopathy, and diabetes

• Approximately 1 in 113 people have this condition in Scotland and Ireland and 1 in 150 in England and Wales
• GH is also known by other names such as hereditary haemochromatosis, familial haemochromatosis and bronze diabetes.

Next step

Genetics