Study identifies gene that may distinguish psoriasis from psoriatic arthritis

A gene has been identified and implicated in the development of psoriatic arthritis but not psoriasis, which could help researchers begin to understand the differences between the two conditions, according to the results of a 3-year study.

Researchers analyzed 129,874 polymorphic and single-nucleotide polymorphisms (SNPs) from 1,962 patients with psoriatic arthritis (PsA) and 8,923 control individuals using a genotyping array to fine-map previously reported immune-related, known psoriasis susceptibility loci and others.

Anne Barton

After principal component analysis correction, genome-wide significance was seen in eight loci, seven of which were previously reported in psoriasis studies. Detailed statistical analyses identified a PsA-specific risk locus at chromosome 5q31, distinct risk variants for PsA at a known psoriasis susceptibility locus and evidence that CD8+ T cells are a relevant cell type, according to the researchers. Additionally, an independent, novel risk locus for susceptibility to psoriasis was identified at chromosome lq31 to a variant in DENNDIB.

Other results included the identification of three independent effects to the major histocompatibility complex class-one molecules by imputation of human leukocyte antigen classical alleles and amino acids.

“Our study is beginning to reveal key insights into the genetics of PsA that explain fundamental differences between psoriasis and PsA,” lead author, John Bowes, PhD, said in a press release. “Our findings also highlight that CD8+ cells are likely to be the key drivers of inflammation in PsA. This will help us to focus on how the genetic changes act in those immune cells to cause disease."

It may be possible to identify those at higher risk for developing PsA, according to one of the study authors.

“By identifying genes that predispose people to PsA but not psoriasis, we hope in the future to be able to test patients with psoriasis to find those at high risk of developing PsA,” Anne Barton, FRCP, PhD, said in the release. “Excitingly, it raises the possibility of introducing treatments to prevent the development of PsA in those individuals in the future."

The discovery may also lead to the development of new treatments, according to the release.

Reference:

Bowes J, et al. Nat Comm. 2015;doi:10.1038/ncomms7046.

Disclosures: The researchers report no relevant financial disclosures.