A genetic study of eczema, which has been described as the “largest in the world to date”, has increased the number of risk loci (areas on a chromosome) linked to atopic dermatitis by 50 per cent. This increases our understanding of the pathology and raises the prospect of new treatments, say the authors of the study.

The researchers performed a meta-analysis of 26 studies enrolling about 15.5m genetic variants in 21,399 eczema patients and 95,464 controls of European, African, Japanese and Latino ancestry. They replicated the findings in 32,059 cases and 228,628 controls from another 18 studies.

The analysis revealed 10 new risk loci linked to eczema, bringing the total to 31. The new loci include genes that seem to regulate innate host defences and the function of T cells, which seem to drive skin inflammation in atopic dermatitis. The findings support the thinking that autoimmune mechanisms probably contribute to atopic dermatitis.

Based on European studies that enrolled patients with clinically defined eczema, previously established and newly identified loci explain approximately 12.3 and 2.6 per cent of the risk of developing atopic dermatitis respectively.

The authors note that “there appears to be a substantial genetic overlap with other inflammatory and autoimmune diseases”, such as inflammatory bowel disease. Some, but not all, loci overlap with established loci in other atopic diseases, including seven with asthma, seven with allergic sensitisation and six with self-reported allergy.

The study supports developing drugs that target aberrant immune responses in eczema. The authors note, however, that the findings do not detract “from the importance of maintaining the skin barrier” in the prevention and treatment of atopic dermatitis.

“Though the genetic variants identified in this current study represent only a small proportion of the risk for developing eczema – they are in no way deterministic, rather they slightly increase the risk – they do give new insights into important disease mechanisms, and through ongoing research in this area these findings could be turned into treatments of the future,” comments Lavinia Paternoster from the MRC integrative epidemiology unit at the University of Bristol, who led the study.

_{(Nature Genetics doi:10.1038/ng.3424)}