Can rosacea be passed in the family?
Rosacea is a complex disease involving multiple factors and causes, which makes it difficult to link to just one gene. It is a chronic condition that results in facial redness. Some experience redness of the face as the only symptom of rosacea, while others may experience red bumps, white bumps, itching, burning, stinging and overall sensitivity of the face. In some people, rosacea primarily affects the eyes. Finally, some cases of rosacea lead to skin thickening of the nose, chin, ears and other areas. As you can see, rosacea’s complexity is due to the fact that its symptoms can look and act differently in different people. This is one reason why it is very difficult to pin the cause of rosacea to a single gene.
Researchers have previously been able to demonstrate that rosacea is in part caused by a disruption in normal immune system function. Specifically, they found that a protein called LL-37 is overproduced by the immune system, leading to increased immune response and inflammation.
However, it is also well established that rosacea occurs at much higher rates in people of northern European descent. In addition, many patients with rosacea report that other family members have the condition as well. This suggests that genetics may play a role in the development of rosacea, causing researchers to dig deeper. In fact, a recent twin study demonstrated that immune disruption is not the only reason for rosacea.  Those researchers compared the rate of rosacea occurring in identical twins (similar genes) to that of fraternal twins (do not have similar genes). They found that identical twins are more likely to both have rosacea than fraternal twins, and this suggests that rosacea is caused, in part, by an inherited trait. But which genes are responsible for this? A 2015 study compared the genetic material of people with rosacea to those without rosacea and demonstrated that certain genes are expressed at higher levels in people with rosacea. These genes play a role in immune response, which is consistent with previous knowledge about immune dysregulation and dysfunction in relation to rosacea.
Overall, current research suggests that there is a genetic component to rosacea, but other factors relating to the immune system are at play as well.