Psoriasis is not caused or spread by spontaneous genetic mutations in the skin, new research suggests.
These findings come from a study published in Nature Genetics.
Researchers sequenced genes from keratinocytes collected from skin samples from 111 people with psoriasis. They did not find any mutated genes in the psoriatic patches that were not also mutated in the individual’s unaffected skin tissue.
This team took skin samples from the forearms of subjects, from both psoriasis patches and healthy skin. They used laser capture microdissection to isolate 1,182 samples, which were then analyzed by whole genome or exome sequencing.
They found minimal differences in the types of mutations seen in healthy skin versus psoriasis patches and only a slight increase in the number of mutations. In addition, no functional differences were seen between psoriasis and non-psoriasis tissue, suggesting the condition is not linked to a specific somatic mutation in the skin.
The team identified four new driver mutations that gave skin cells an advantage over their neighbours, all found in both psoriasis patches and other skin tissue. They also identified a mutational signature linked with the use of psoralens, a compound sometimes used as part of a treatment for psoriasis flares. However, these mutations were found in patients who had been prescribed psoralens along with those who had not, which they write suggests the mutation could have come from environmental exposure.
“Psoriasis is a condition that affects millions of people around the world, impacting their quality of life, and very little is known about why it happens and how we can treat it,” said senior author Dr. Carl Anderson, in a press release. “While our research did not find a gene where somatic mutations increase susceptibility to psoriasis, we were able to quantify the mutational consequences of psoralens exposure on the skin, defining a mutational signature that may help future research. We also found that the way in which skin cells develop from stem cells is, reassuringly, unaltered by psoriasis.”
Dr. Anderson is Head of Human Genetics and Senior Group Leader at the Wellcome Sanger Institute in Hinxton, England.