Psoriasis and TS

what did that say?!?

The OMIM website that I use for these gene investigations just said that a susceptibility to psoriasis was on gene 4q31 right next to the anxiety disorder gene!

My mother has severe psoriasis...

So it looks like it's all Dad's fault!

Perhaps I should explain.

Most people know the basic explanation of inheriting genes from parents. Each person has 48 chromosomes. When a man's spermatozoa, and a women's ova are made, the 48 chromosomes split in half, so you only have 24 in each sperm/egg (called a zygote). When two of these zygotes meet, they produce a 48 chromosome cell which then divides to form the baby.

The basic idea is that when the zygotes form half of the chromosomes go to one side of the cell, and half to the other, then the cell splits.

This is called meiosis.

The procedure is not actually that simple. During the process of meiosis, there is crossover. This means that the chromosomes, instead of heading one by one to the sides of the cell, actually swap some genetic information on the way.

Imagine for a moment that chromosomes are pairs identical twins. So you'd have 24 pairs of twins in a human. Now crossover can only occur between a person and his twin, so let's look at the Jones twins specifically. One Jones twin is holding an apple, the other is holding an orange. Now, if there was no crossover, the twins would just walk to either end of the room. The orange would end up at one end of the room and the apple at the other.
But, if there is crossover, one twin could pass his fruit to the other before they walk to either end of the room. So at the end of the room you're standing in, you could have an apple, an orange, an apple and orange, or no fruit at all. This is why you don't end up exactly like a cross between your parents, there is more variation.

The reason I mention this, is that when two genes are close together, they are more likely to cross over together. Say, a worm sitting on the apple is more likely to be passed to the other twin with the apple than a shoe would be. So if psoriasis is close to anxiety on 4q31 then any abnormalities are more likely to be passed through together. So the chances are that if I got my anxiety gene from Mum, I would probably have psoriasis too.

So it looks like it's all Dad's fault!