Although the itchy, red rashes that plague people with atopic dermatitis are usually set off by environmental irritants and allergens, the root of the condition (a type of eczema) is thought to be genetic.
A new report, published online this week in the journal Nature Genetics, shows that a DNA variation previously associated with Crohn’s disease may be one of the genetic risk factors for atopic dermatitis.
Researchers analyzed the genetic data of more than 3,500 people with atopic dermatitis and more than 4,900 controls from Germany, Poland and the Czech Republic. Their results showed that compared people with two Cs at a specific SNP, to those with one T have 1.16 times higher odds of having atopic dermatitis, while those with two Ts have 1.47 times increased odds.
The researchers estimate that 13% of the population with European ancestry has two Ts at this SNP.
A recent report associated the SNP with Crohn’s disease. In that study, each T increased the odds of Crohn’s by 1.16 times. The authors of the current atopic dermatitis study note that Crohn’s and atopic dermatitis share several features — recurrent bouts of inflammation, cells that fail to form proper barriers (in the intestine and skin, respectively) and deficient immune responses against bacterial infections. They suggest that the association of with both conditions may explain why there is a high incidence of eczema in people with Crohn’s disease.