While it has long been observed that rosacea may tend to run in families, the first genome-wide association study of rosacea may have discovered the genetic variants that are linked to this chronic skin disorder -- as well as potential connections between rosacea and certain autoimmune disorders.

In a new study funded by the National Rosacea Society, Dr. Anne Chang, assistant professor of dermatology at Stanford University, and colleagues performed an investigation of the human genome to identify a potential genetic basis for rosacea. Clients of 23andMe, a personal genomics and biotechnology company, were given a survey asking whether a health-care provider had ever diagnosed them with the condition. Those who said they had been diagnosed with rosacea were made part of the test group, and those who had not were made part of the control group. 

The researchers then compared the DNA of both groups to search for genetic variations that were common among the rosacea sufferers but not in those without the disorder. The experiment was run twice to help ensure the results were consistent. The first included 2,618 rosacea patients and 20,334 controls, and the second had 3,205 rosacea patients and 26,262 controls.

The study results pinpointed two specific areas in the genomes of rosacea sufferers that were strongly associated with the disorder, including genetic variants in or near the HLA-DRA and BTNL2 genes. Interestingly, these areas of the genome are also associated with autoimmune disease, including type I diabetes, which shares with rosacea an abnormal proliferation of blood vessels, and celiac disease, which can have skin manifestations associated with the small intestine.

In addition to the genome-wide association study, the researchers examined skin biopsies from six individuals with rosacea and confirmed that both HLA-DRA and BTNL2 proteins could be found. This preliminary work suggests that HLA-DRA and BTNL2 may be biologically relevant in rosacea, potentially leading to advances in its treatment, prevention or cure.

In the recent study article, published in the Journal of Investigative Dermatology, the researchers also noted that the potential connection between rosacea and diabetes merits further investigation. “As rosacea is a highly visible disease, it may be a cutaneous sign that cues health care providers to consider screening for diabetes,” they said. They noted that future research may help individuals at risk for both disorders to be readily identified, allowing them to avoid triggers, obtain screening and seek early treatment to avoid long-term adverse effects. 

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