Researchers at the Stanford University School of Medicine, in collaboration with the genetics company 23andMe, have identified a genetic basis for rosacea, an incurable and poorly understood skin disease.
Treatment options for rosacea now are limited, but finding out what causes the disease could help scientists identify new targets for treatment and understand its links to other known diseases.
A paper describing the study’s findings was published online today in the Journal of Investigative Dermatology.
Rosacea causes skin on the face to redden and can result in acnelike bumps. “Rosacea is a very visible, inflammatory disease of the skin,” said Anne Lynn Chang, MD, lead author of the paper and an assistant professor of dermatology at Stanford. “It can lead to permanent scarring.”
According to the National Rosacea Society, the disease affects around 14 million Americans, or 5 percent of the population. In northern European countries, the prevalence is greater, at around 10 percent of the population. Rosacea is most visible in fair-skinned people but affects people of all skin types.
“It is one of the most common things we see in dermatology clinics that is incurable and not easily treatable,” Chang said.
Rosacea patients can also experience itching, stinging and burning sensations on the affected skin; these feelings, accompanied by the visible skin changes rosacea causes, can make sleeping, concentration and social interactions difficult. Other research suggests the disease could be associated with underlying systemic diseases that affect other organ systems in addition to the skin.
A cutaneous sign
Chang and her collaborators partnered with 23andMe to look for the genetic basis of rosacea. 23andMe is a personal genomics and biotechnology company based in Mountain View, California. Customers’ genomes are sequenced from saliva samples they submit to the company. 23andMe customers of European descent agreed to take a survey that asked whether a health-care provider had ever diagnosed them with rosacea. Those who answered yes were grouped together, and those who answered no were placed in a control group. The scientists ran two separate experiments to help ensure the results were consistent. The first experiment had 2,618 rosacea patients and 20,334 controls, and the second had 3,205 rosacea patients and 26,262 controls.
The researchers compared the genomes of rosacea patients and controls and looked for differences in the DNA building blocks, called nucleotides, in people diagnosed with rosacea. Such differences, called single nucleotide polymorphisms, occur when one nucleotide, such as guanine, is substituted for another, such as cytosine. This kind of analysis is called a genome-wide association and, because the entire genome is searched, is an unbiased way to look for genetic links to disease.
Two areas linked to rosacea
Only two areas of the genome were associated with having rosacea, and these two areas were located near genes known for their role in inflammatory and autoimmune diseases such as multiple sclerosis, diabetes, sarcoidosis and inflammatory bowel disease. Single nucleotide polymorphisms located near genes can play a role in regulating that gene — for example, regulating whether the gene is expressed.
Chang described the study as a forward-looking examination of the genetic associations of rosacea. “The next step is to look more into these associations of rosacea with other diseases,” she said, “and explore whether the inflammation in rosacea is a cutaneous sign of risk for other disease.”
Other Stanford co-authors of the paper are Inbar Raber, graduate student; Jin Xu, PhD, postdoctoral scholar in dermatology; Rui Li, research assistant; and former postdoctoral scholars Robert Spitale, PhD, and Julia Chen, PhD.
This study was supported by the National Institutes of Health (grant 2R44HG006981) and the National Rosacea Society. Information about Stanford’s Department of Dermatology, which also supported the work, is available athttp://dermatology.stanford.edu.