CAH is what is known as a "recessive genetic condition".I'll try and explain a bit.
"Genes" are bits of DNA that define how certain characteristics of you appear. You have genes for eye colour, genes for hair colour, etc.
Everyone has 2 genes for a characteristic, and these can be dominant or recessive, this is what you're asking about.
I'll take eye colour just for the sake of example (let's say B = brown and g = green)
Mother - Bg
Father - gg
If we say that capital B is DOMINANT, and little g is RECESSIVE, things start to become clearer.
The mother has BROWN eyes, because the B gene is dominant, and therefore the "g" gene is 'ignored', because it is recessive.
The father has GREEN eyes, because there is only the "g" gene present.
So, so far we know that for every characteristic there are 2 genes, and DOMINANT genes "beat" RECESSIVE genes.
CAH is a RECESSIVE condition, so you need both genes to be CAH in order to have it. If you only have one, you are known as a "carrier" - you have a CAH gene, but the other dominant gene means it is ignored, so you're not actually affected by it.
What this means is that if 2 carriers have a child, there is a CHANCE that the child might have CAH.
Let's say "c" is the CAH gene, and "N" is the non-CAH gene
Father - cN - Father is a carrier
Mother - cN - Mother is a carrier
Since you get half of your genetic characteristics from each of your parents, there are different combinations that can happen.
NN - No trace of CAH
Nc - CAH carrier, but not affected
cN - CAH carrier, but not affected
cc - Has CAH
So there's a 25% chance that a child will have CAH.
Hope that helps you make sense of things, if not then say and I'll try to explain things a bit better.
Rick
