Researchers found that people with certain stretches of DNA had an increased risk of psoriasis, but only if they were overweight.
They said the findings will help to explain how interactions between genes and the environment can affect risk of psoriasis.
Little is known about how factors such as adiposity interact with genetic make-up to influence risk of skin disorders such as psoriasis. However, genome-wide association (GWAS) studies have uncovered genes linked to psoriasis.
To examine the link, researchers used GWAS data on 337 participants with psoriasis and 8,857 controls. Patients were assessed for BMI, waist circumference and other measurements.
The researchers identified two DNA sections, single nucleotide polymorphisms (SNPs), that showed a correlation with BMI. One, in the IL23R gene, was linked to waist circumference as well.
Overweight patients with this genetic marker face an increased risk of psoriasis.
Researchers found the gene containing the SNP encodes a protein with an important role in autoimmune inflammatory diseases.
Li W-Q, Han J-L, Zhang M-F et al. Br J Dermatol 2013; 168: 639-42