SNPwatch: New Genetic Insight into the Causes of Eczema

Sometimes called the “itch that rashes”, atopic dermatitis, or eczema, is a relatively common condition, affecting up to one in five children and one in 30 adults (many people outgrow it by early adulthood). It can be both physically painful and emotionally difficult to live with since it’s not a disorder that hides inside of you. Although atopic dermatitis appears to run in families, the genetics underlying this condition are not well understood and up until recently only a few genetic variants had been linked to it.

New findings published in December in Nature Genetics by lead author Lavinia Paternoster now add more genetic variants to the picture. This study, performed in conjunction with researchers from around the world, analyzed data from over 50,000 people with European ancestry, roughly 11,000 of whom had atopic dermatitis. In addition to confirming previously discovered associations with atopic dermatitis — with functional variants of the filaggrin gene, which are present in 25-50% of people with this disorder, and in a region of chromosome 11 — the findings also provide further genetic evidence that this condition likely results from defects in immunological and skin barrier pathways.

The Link Between Atopic Dermatitis, Asthma and Allergies

Many people with atopic dermatitis also suffer from asthma or allergies (hay fever and food allergies), but there isn’t a 1:1 correlation. Environmental factors that exacerbate atopic dermatitis — allergens in the air, some chemicals, and emotional stress — can also trigger asthma. People with atopic dermatitis may also react positively on skin allergy tests. On the genetic side of the equation, these conditions tend to run together in families and although a number of studies have implicated functional variants of the filiggrin gene in all of them, researchers are still teasing out the details. 23andMe does not report on these relatively rare variants.

One of the SNPs newly associated with atopic dermatitis, , is located in the OVOL1 gene, which encodes a protein that plays important roles in skin cells. Another association was found at (equivalent to reported in the study). This SNP is located near a group of immune system genes on chromosome 5 that have been tied to other immune diseases like psoriasis, Crohn’s disease and asthma.

When the researchers looked in more detail at genetic variants involved in the immune system, they found an even stronger association at , located in the IL13 gene. Their in-depth analysis suggests that the associations on chromosome 5 are centered on the immune genes IL13 and IL4, which encode cytokines — small molecules that circulate in the body and regulate the immune system.

(23andMe customers can view their data for , and other SNPs in their Atopic Dermatitis Preliminary Research report.)

Although the causes of atopic dermatitis are still a puzzle, scientists are beginning to learn more about the genetic components and their relationship to environmental factors. Future research may follow up on the immune system and skin-related pathways identified by Paternoster and colleagues and perhaps further determine if atopic dermatitis, asthma and allergies are genetically linked.

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

Editor’s note: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who purchased prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will not. Those customers will have access to ancestry information as well as access to their uninterpreted raw data.

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