Lynn, As I promised, I learned a little about the genetics of the 21-hydroxylase form of CAH. Before I go into that you wanted to know what questions to ask. Frankly the ones you already came up with are fine. The truth is that the genetic analysis of CAH has more theoretical value than any practical application to the treatment of CAH patients. I have only two questions you might want to add to the ones you already raised: 1. Do your husband's results change the usual 1 in 4 chance that any future children would have CAH? 2. If you had another child with CAH would it be classic salt wasting like your son's or some other form of CAH? Now for the fun part. There are two genes, located on chromosome #6, that are involved in the 21-hydroxylase (21-OH) form of CAH. The first is a functional gene designated CYP21. In close proximity to CYP21 there is an unexpressed (non functional) pseudo-gene called CYP21P. It is the functional CYP21 gene that is responsible for producing the 21-OH enzyme. As of 1999 over 40 possible mutations that can give rise to a 21-OH enzyme deficiency have been identified in the CYP21 gene. The cells in our bodies have a pair of each of 23 different chromosomes for a total of 46 chromosomes. An egg or a sperm gets only one half of each chromosome pair for a total of 23 chromosomes. During the formation of the egg or sperm the normal body complement of 23 chromosome pairs line up with each other and swap genetic material. After this, the newly recombined chromosomes separate and 23 go into one egg or sperm and the other 23 go into another egg or sperm. This process, called meiosis, mixes the genes inherited from the person's father with those inherited from the mother before they are passed on to the next generation. This is why children show an unpredictable mix of characteristics from their parents. It is during the exchange of genetic material that occurs in meiosis that the CYP21P pseudo-gene plays a role. The functional CYP21 and the nonfunctional CYP21P are so close together that there are times when they exchange pieces. When this happens the resulting recombinant CYP21 gene is likely to be defective. It is also possible for the CYP21 gene to be completely deleted. This is estimated to account for about 20% of classic CAH cases and is associated with the salt wasting form. This last outcome might possibly what was meant when they said that your husband's test came out blank. Since you and your husband already are CAH carriers the recombinantion events that produced the defective (or missing?) CYP21 gene had to have occurred in Ryan's grandparents generation or even earlier. OK I'm done. I know this stuff is a bit much for you but I actually find it interesting. I have also found that the best way to learn something myself is to try to explain it to someone else. Good luck on Tuesday, Joan