Hemochromatosis: Genetic Iron Overload Risk Highest in Ireland & Scottish Hebrides

For people with ancestry in specific regions of the UK and Ireland, a genetic predisposition to iron overload – historically known as the ‘Celtic curse’ – carries a significantly elevated risk. New research, mapping genetic risk for hemochromatosis across the British Isles and Ireland, reveals that as many as one in 54 individuals with roots in northwest Ireland may carry the gene variant responsible, whereas in the Outer Hebrides, the figure is approximately one in 62. The findings, published in Nature Communications, underscore the need for targeted genetic screening to identify those at risk before irreversible organ damage occurs.

Understanding Hemochromatosis: The ‘Celtic Curse’

Hemochromatosis is a genetic disorder where the body absorbs too much iron from food. This excess iron accumulates in organs – the liver, heart, pancreas, and joints – over years, potentially leading to serious health complications including liver disease, liver cancer, arthritis, and diabetes. The condition often develops slowly, with symptoms appearing decades after iron begins to build up, making early detection crucial. Fortunately, treatment is available and effective: regular blood donation can lower iron levels and prevent much of the harm. Haemochromatosis UK provides comprehensive information about the condition and available support.

The genetic basis of hemochromatosis lies in inherited changes to DNA, known as genetic variants. In the UK and Ireland, the most common culprit is a variant called C282Y. Researchers at the University of Edinburgh analyzed genetic data from over 400,000 participants in the UK Biobank and Viking Genes studies to determine the prevalence of this variant across 29 regions.

Geographic Hotspots and Ancestry

The study pinpointed areas with particularly high rates of the C282Y gene variant. Northwest Ireland showed the highest prevalence, with approximately 1.85% of the population carrying the variant. The Outer Hebrides followed closely at 1.61%, and Northern Ireland at 1.54%. Mainland Scotland also exhibited elevated risk, particularly in Glasgow and southwest Scotland, where around 0.83% of people carry the variant. These findings reinforce the historical association between these regions and the condition, lending credence to the nickname ‘Celtic curse’.

Interestingly, analysis of NHS England records revealed a pattern mirroring the genetic risk. White Irish individuals were nearly four times more likely to receive a diagnosis of hemochromatosis than white British individuals. Within England, Liverpool showed an unusually high diagnosis rate – 11 times higher than in Kent – likely reflecting the city’s historical influx of Irish immigrants during the 19th century, when over 20% of Liverpool’s population had Irish origins. This highlights how migration patterns can influence the observed distribution of genetic conditions.

Diagnosis Gaps and the Need for Targeted Screening

While diagnosis rates generally align with genetic risk, some areas in England – Birmingham, Cumbria, Northumberland, and Durham – reported fewer cases than expected based on their genetic profiles. This suggests potential underdiagnosis in these regions, indicating a need for expanded screening efforts. Unfortunately, comparable data from Scotland, Wales, and Northern Ireland were unavailable for this part of the analysis.

Professor Jim Flett Wilson, Chair of Human Genetics at the University of Edinburgh, emphasized the importance of early detection. “If untreated, the iron-overload disease hemochromatosis can lead to liver cancer, arthritis and other poor outcomes,” he stated. “We have shown that the risk in the Hebrides and Northern Ireland is much higher than previously thought… Early detection prevents most of the adverse consequences and a simple treatment – giving blood – is available. The time has reach to plan for community-wide genetic screening in these high-risk areas.”

What Does This Signify for Individuals?

It’s important to understand that carrying the C282Y gene variant does not automatically mean someone will develop hemochromatosis. Approximately half of those who inherit the variant will eventually develop the condition. Genetic testing can identify carriers, but it’s not a definitive diagnosis. Further testing, such as measuring iron levels in the blood and assessing liver function, is necessary to confirm the diagnosis.

The study’s findings do not warrant widespread, untargeted screening for hemochromatosis across the entire UK and Ireland. Instead, the researchers advocate for focused screening programs in the identified hotspots – northwest Ireland, the Outer Hebrides, Northern Ireland, and specific areas of Scotland – where the prevalence of the C282Y variant is highest. This targeted approach would maximize the efficiency of screening efforts and identify the greatest number of individuals at risk.

The Role of Public Health and Future Directions

Jonathan Jelley, CEO of Haemochromatosis UK, highlighted the potential impact of the research. “This hugely important work has the potential to lead to greater targeted awareness, increased diagnosis and better treatment pathways for thousands of people affected by genetic hemochromatosis.” The charity is already working to prioritize support for hotspot areas and educate clinicians about the condition. RCSI University of Medicine and Health Sciences was a partner in the study, demonstrating a collaborative approach to addressing this genetic health challenge.

Torcuil Crichton, the Labour MP for Na h-Eileanan an Iar (the Western Isles), who himself has hemochromatosis, is actively advocating for community-wide screening in his constituency. He believes the Western Isles, with its distinct and relatively isolated population, would be an ideal location for a pilot screening program. He has raised the issue with Ministers in the House of Commons and is urging the UK National Screening Committee to reconsider its current position.

Next Steps: Review and Potential Pilot Programs

The study’s findings are likely to prompt a review by the UK National Screening Committee, which evaluates the evidence for introducing new screening programs. A pilot screening program in the Western Isles, as proposed by MP Crichton, could provide valuable data on the feasibility and effectiveness of targeted screening for hemochromatosis. Further research is also needed to investigate the prevalence of other genetic variants that can cause iron overload and to develop more refined risk prediction models. The UK National Screening Committee provides information on current screening programs and the process for evaluating new ones.