The origins of the Irish travellers and the genetic structure of Ireland

Genomic insights into the population structure and history of the Irish Travellers

The Irish Travellers are a population with a history of nomadism; consanguineous unions are common and they are socially isolated from the surrounding, ‘settled’ Irish people. Low-resolution genetic analysis suggests a common Irish origin between the settled and the Traveller populations. What is not known, however, is the extent of population structure within the Irish Travellers, the time of divergence from the general Irish population, or the extent of autozygosity. Using a sample of 50 Irish Travellers, 143 European Roma, 2232 settled Irish, 2039 British and 6255 European or world-wide individuals, we demonstrate evidence for population substructure within the Irish Traveller population, and estimate a time of divergence before the Great Famine of 1845–1852. We quantify the high levels of autozygosity, which are comparable to levels previously described in Orcadian 1^st/2^nd cousin offspring, and finally show the Irish Traveller population has no particular genetic links to the European Roma. The levels of autozygosity and distinct Irish origins have implications for disease mapping within Ireland, while the population structure and divergence inform on social history.

Cardiovascular disease and risk factors in an indigenous minority population. The All-Ireland Traveller Health Study

BACKGROUND

The Traveller community are an indigenous minority group in Great Britain and Ireland who experience premature mortality. While minority populations worldwide are known to have high rates of risk factors for cardiovascular disease (CVD), Traveller CVD risk has not previously been defined.

DESIGN

All-Ireland cross-sectional census survey of the Traveller minority population (n = 10,615 families).

METHODS

A subsample of adult respondents completed a health survey (n = 2023). CVD was defined as self-report of doctor-diagnosed heart attack, angina, or stroke. CVD risk factors and measures of social position were examined in the Traveller group using age-adjusted prevalence and prevalence ratios (PR). Comparisons were made with a general population sample of low socioeconomic status.

RESULTS

Age-adjusted prevalence of CVD in the Traveller population was 5.6% (95% CI 4.6-6.8), similar to that in the comparator population. Compared to those without CVD, Travellers with CVD had a higher prevalence of self-report of diabetes, hypertension, hypercholesterolaemia, current smoking, and a measure of distrust. Compared with the general population sample, Travellers had a higher prevalence of diabetes (adjusted PR 2.8, 95% CI 2.1-3.8) and lifestyle-related risk factors such as smoking (PR 1.3, 95% CI 1.2-1.4), fried food consumption (PR 2.8, 95% CI 2.4-3.2), and physical inactivity (PR 1.3, 95% CI 1.2-1.4).

CONCLUSIONS

This comprehensive census survey confirms CVD as an important health risk in the economically disadvantaged Irish Traveller community. Our findings add to the international knowledge base on minority populations and CVD risk.

Human leucocyte antigen class II polymorphism in Irish patients with multiple sclerosis

The contribution of human leucocyte antigen (HLA) to the genetic risk for multiple sclerosis (MS) in patients of Northern European Caucasoid ancestry has been known since the 1970s. The northern part of Ireland, including county Donegal, is known to be a high-risk area for the development of MS. Recorded prevalence rates for county Wexford in the south-east Ireland have been markedly lower and suggest the existence of a prevalence gradient within the island. To evaluate the association of HLA-DRB1 and -DQB1 haplotypes with MS in both Wexford and Donegal, we examined a total of 118 patients and 400 regionally matched controls. The aim of this exploratory study was to test the possibility of heterogeneity in HLA class II associations with MS and to identify potential predisposing or protective haplotypes, associated with MS risk in Ireland. We confirmed the association of DRB1*1501-DQB1*0602 haplotype carriage with MS in both Wexford [odds ratio (OR) = 2.95, P= 0.0020, P(cor)= 0.0220] and Donegal (OR = 2.29, P= 0.0030, P(cor)= 0.0420). A higher frequency and a significantly higher homozygosity rate of this haplotype in Donegal are likely contributing factors to the higher prevalence of MS in Donegal compared with Wexford. The distribution of HLA class II alleles among Irish MS patients and controls establishes that there is heterogeneity in HLA class II associations with MS within Ireland.