There's clearly a genetic predisposition. But the exact cause of the disease is not known, and therefore it's hard to predict who's going to get it. Even within a family where there are affected relatives with psoriasis or psoriatic arthritis, we have yet to understand for sure what the gene or genes are that are involved in the perpetuation of the disease. There are a number of groups around the world at the present time working to try and identify the genes that cause both psoriasis and psoriatic arthritis, and probably over the next couple or years, two to five years at the most, that will be understood, but at the moment we really don't know who gets it. Yes, men and women actually do get it equally, which is different from, say, rheumatoid arthritis where women are three times more likely to get it than men or in ankylosing spondylitis, which is inflammatory arthritis of the back, where men are many more times more likely to get it than women.
Psoriatic arthritis has equal gender.
It's an equal opportunity disease. Unfortunately, I guess. That's very variable as well. If we look at our own cohort of patients in our clinic, the mean age of onset is in the 30s, about 36. However, we do recognize that psoriatic arthritis can affect children, and we do recognize that psoriatic arthritis may affect older people, and in fact, there is recent publications to suggest that people who get it in an older age actually have a more difficult condition.