Medically reviewed by Dr. Nancy Shannon, MD, PhD on June 21, 2021
Medical researchers have yet to pin down the precise causes of rosacea for most people, but most agree that genetics are a key factor. While environmental conditions can play a role, DNA is the loudest voice in the room when it comes to rosacea.
The specifics of exactly what role one’s genetics play in the development of rosacea is highly nuanced and still being debated by scientists. Here’s what you need to know:
Rosacea and Genetics
It’s been known for some time that rosacea likely has a genetic basis given its most common risk factor: ancestry. In the United States, rosacea affects about 5% of the population, but that percentage doubles for northern European countries. Those with Celtic or Scandinavian ancestry are much more likely to develop rosacea than those without, suggesting a strong genetic foundation for the condition.
For quite some time, this was just about as far as genetic research into rosacea had gotten. Recent developments in gene-mapping technology, however, have contributed to breakthroughs in the study of the relationship between genes and rosacea. A pioneering study conducted by researchers at Stanford and 23andMe in 2015 identified some key commonalities among the genetic profiles of people with rosacea. The researchers noticed that the elements that make up DNA, known as nucleotides, behaved differently for people with rosacea in two regions, both of which were near genes linked to inflammatory and autoimmune conditions. This may indicate that rosacea is somehow linked or may share elements with other such conditions, like diabetes or multiple sclerosis.
Another study, this one conducted in 2018 again by researchers from 23andMe in partnership with GlaxoSmithKline, assessed the genetic profiles of 73,265 people with European ancestry to look for correlations between rosacea severity and genetic makeup. This study identified seven regions where variations in the genetic code appeared to be consequently linked to incidences of rosacea. Of these regions, two are associated with skin types and pigments, two with conditions linked to inflammation and immune response, and one with both. This bolsters the previous study’s findings that rosacea may be linked with inflammatory and autoimmune conditions while also suggesting that the skin pigmentation itself is a factor.
Even though neither of these studies produced a full picture of how rosacea and genetics are interlinked, both reinforced a crucial fact about the condition: due to its likely origins in polymorphisms of the genome, rosacea is very likely to be hereditary. This means that if you have parents or grandparents who have experienced rosacea, the chances that you will as well are elevated.
Other Causes of Rosacea
Even as scientific breakthroughs continue to strengthen the case for seeing rosacea as a genetic phenomenon, there are still some environmental factors that cannot be ignored. Whether they cause or simply contribute to the development of rosacea is unclear, but they’re worth knowing about all the same.
- Immune and Nervous System Responses
As suggested by the studies that showed rosacea’s genetic relationship with autoimmune disorders, some researchers have speculated that processes in the immune system are to blame for rosacea. Cathelicidin is a molecule that the body produces in order to fight bacterial infection, and an overabundance of it can cause the inflammation, redness, and bumps characteristic of some cases of rosacea symptoms. The lesions of some people with rosacea have been found to contain high levels of cathelicidin.
Alternatively, some evidence has suggested a relationship between rosacea and the body’s nervous system. Adenosine triphosphate, or ATP, is one of the most ubiquitous neurotransmitters in the human body and can cause the expansion of blood vessels in the face. Why this happens is not clear, but it goes to show just how multi-faceted the causes of rosacea may be.
- UV Light Exposure
Ultraviolet light is known to increase the body’s production of vascular endothelial growth factor, or VEGF, when the skin is exposed to it via sunlight. VGEF can cause telangiectasia, or the appearance of visible blood vessels on the face, one of the telltale signs of rosacea. A definite causative relationship has yet to be established, but exposure to UV light seems to play a role in the development of rosacea.
Though a correlation between rosacea and large populations of the Demodex folliculorum mite on the face has been established, researchers are still debating what the implications of it are. D. folliculorum mites are present on the skin of all humans, and it’s not clear if large numbers of them cause rosacea or simply arrive in response to it.
The same is true for some strains of common bacteria such as Helicobacter pylori and Staphylococcus epidermidis. Those with rosacea tend to have large amounts of both present in and around their pores, but the precise reason why has yet to be determined.
If you’re feeling overwhelmed by the complexities of rosacea, we’re here to help. Get in touch with a member of our medical team today to learn about which treatments may work best for you.