Psoriasis and Obesity: An Unlikely Duo that Might Share a Genetic Cause

A new study has uncovered a potential shared genetic source between psoriasis and obesity, which could also address a connection among psoriasis, type 2 diabetes, and body mass index (BMI).

An autoimmune disease that involves rapid skin cell growth, psoriasis has been linked to metabolic disorders genetically, through environmental exposure, and because of lifestyle choices like drinking alcohol, smoking, psychological stress, levels of physical activity, and shared immunoinflammatory pathways.

Since patients with metabolic syndrome could experience a systemic inflammation similar to psoriasis, in both cases, the patients would likely have higher levels of certain inflammatory markers — particularly the tumor necrosis factor.

To learn about the shared causes of diseases, Ann Sophie Lønnberg, MD, University of Copenhagen in Denmark and colleagues looked at data for 33,588 Danish twins from 20-71 years.

Participants were required to complete questionnaires about psoriasis that were matched with diagnoses for type 2 diabetes and BMI.

A total of 4.2% of the study participants had psoriasis and 1.4% had diabetes. Additionally, average BMI was 24.5 and 6.3% had a BMI of 30-34 (obese).

According to results, “Psoriasis was present in 7.6% of those with diabetes, but it was only present in 4.1% of those without diabetes. What is more, people with psoriasis had, on average, a BMI of 25 — higher than the BMI of those without psoriasis, which stood at 24.4.”

Researchers found that patients with psoriasis had a greater risk of high BMI and obesity than the healthy patients.

Interestingly, in 720 sets of twins, only one twin of the pair suffered from psoriasis and also had higher BMI, therefore likely to be obese than the co-twin without psoriasis.

Researchers noted that psoriasis patients typically choose a more sedentary lifestyle, which could undoubtedly increase the risk of obesity and diabetes.

While the authors surmised psoriasis and obesity could partially branch out from the same genetic cause, there is not enough evidence to claim whether one condition leads to another.

The authors concluded, “Psoriasis, type 2 diabetes mellitus, and obesity are strongly associated in adults after taking key confounding factors such as sex, age, and smoking into account. Results indicate a common genetic etiology is psoriasis and obesity. Conducting future studies on specific genes and epigenetic factors that cause this association is relevant.”