Psoriasis: Cracking the Genetic Code

A review of multiple studies concluded that psoriasis and several other autoimmune disorders have multiple genes in common and similar response elements.

The findings lead the reviewers to believe that people with psoriasis are more likely to develop additional autoimmune disorder.

They also expect that therapies targeted to addressing those common elements will lead to more tailored and effective therapies. The review, published in Psoriasis: Targets and Therapy on February 22, 2016, was conducted by Nilmarie Ayala-Fontanez, of the Department of Dermatology, Case Western Reserve University in Cleveland, Ohio, in the United States, and colleagues.

According to the researchers, “More than 30 single nucleotide polymorphisms (SNPs) have been associated to contribute to psoriasis risk but only two gene mutations have been found to independently induce psoriasis (IL36RN and CARD14) by affecting both the skin and the immune system.” PSORS1 on chromosome 6p21, PSORS2, on chromosome 17q25, and especially a mutation in CARD14, and IL36RN, which is also known as IL-1F5, along with SNPs are all associated with psoriasis.

Environmental triggers such as physical trauma, stress, pharmaceuticals, alcohol, smoking, obesity, and infections, are also associated with psoriasis.

Psoriasis is considered an “inherited and an immune-mediated disease,” say the authors. However, they note, “controversy exists to whether psoriasis should be considered a bona fide autoimmune disease given that no auto-antigen has been conclusively discovered that triggers the disease and no self-reactive T cells have been identified.” There are two theories: one is that molecular mimicry makes psoriasis an autoimmune disease, and the other is that bacterial microbiota triggers psoriasis. Both theories have substantial evidence.

Psoriasis is associated with several other autoimmune diseases, and more research is being done.

Rheumatoid arthritis, celiac disease, Crohn’s disease, atopic dermatitis, systemic lupus erythematosus, Sjogren’s syndrome, and vitiligo have all been studied in association with psoriasis. The reviewers conclude, “Further research to refine the common autoimmune elements should lead to the development of more tailored therapies for all autoimmune disorders.”