What is psoriasis?

No one fully understands what causes psoriasis yet, but doctors have several
theories. We have known for a long time that psoriasis seems to run in families.
This is not to say that if you have the disease your children definitely will, or that
if your parents didn’t you won’t either. Rather, there is a marked increase in
psoriasis among people whose parents, grandparents or siblings have the disease.
If one spouse has psoriasis, a couple’s children have a one-in-four chance of
developing psoriasis too. If both parents have psoriasis, there is a 50:50 chance
that their children will inherit the disease. If one fraternal twin has psoriasis,
there is a 70% chance that the other will, and there is a 90% chance that if one
identical twin has the disease, so will the other.
Although we have nailed down the numbers, dermatologists and genetics
experts still don’t know exactly how psoriasis is passed from one generation to
the next, but we are getting closer to an answer. Recent study of blood samples
has suggested to researchers that there are several genes that transmit psoriasis.
The exact locations of the genes remain unknown (there are millions of genes on
each of the 26 chromosomes), but scientists are currently trying to identify them
precisely. They may be able to alter the way they affect people who are born
with them and also possibly lead to new treatments. A greater understanding of
the psoriasis genes may also help to select the ideal treatment for some patients.