If you study genetics more closely, at conception, as the cells are dividing this is where the genetic make up is decided and more often than not it works on dominance of a certain gene over another---although there are exceptions.  For example brown eyes are more dominant than blue.  You may ask why Mother Nature would want to give brown eyes this prestigious position of being dominant over blueeyes?  I feel it is a purely practical reason.  Survival.  When we are frightened don’t our pupils sometimes dilate in response?  Maybe then its because this is harder to pick up with brown eyes but is often very obvious with a blue eyed person.  The same example could be used for genetics in CAH.  Why is 21 hydroxylase the most common out of the others?  Perhaps this is Mother Nature way of trying to eliminate the actual CAH gene from the whole future boy meets girl scaneario.  In other words, make it so severe that the off spring cannot possibily survive?  After all I’m sure she never expected us to cotton on and start using hydrocortisone and without that most of the severe sufferers would simply not survive. 

 

If one parent carries a severe strain and the other partner suffers CAH BUT it is so mild that the symptoms are not too bothersome unless there is severe stress, then what is Mother nature going to say is more dominant.  If you study this topic on the Cares Foundation web site it explains that simple forms of CAH it is believed are more common.  Some 1 in a 100 – 1000 people suffer the condition in varying degrees from extremely mild to severe.  This makes them a suffer not a carrier.  So if there are any parents who perceived that they were a carrier but have always had problems with cortisol and other symptoms of CAH this makes them  sufferer NOT a carrier and they need tests to eliminate or investigate further.  Carriers just silently carry the gene to the next generation.  In this way it can pass through many generations undetected.  If you have a couple for example each with the above traits i.e. a sufferer with mild CAH who isn’t aware of it and a carrier who hands down the severest form that can be handed down to a the child and he/she becomes a carrier---ask yourself exactly what are they carrying?  Could be three possibilities here:

 

a./  The mildest form that was passed on from one parent.

 

b./  The severest form from the other parent.

 

c./   A combination of the two together cooked up especially by the gene pool.

 

 

As for children that "suffer" from the combinations of the above handed down to them the same may apply. 

It was my understanding that a sufferer can have CAh to such mild degree that it doesn’t become apparent until much later in life (late as 50's).  Gradually the negative affects do compound and the symptoms then manifest themselves.  Now as more children are treated with CAH, and live beyond 10 days or reach adulthood unaffected apart from steroid therapy and then have families of their own, you have a much wider variety of strains added to the pot.  The chances are no doubt going to be as high as diabetes---infact I think I read somewhere that the simple form is MORE common than diabetes!

 

JH