I know when my boy was diagnosed at 4 1/2 weeks of age because it is a rarity in my home state we had a lot of student doctors come by and with my permission they all checked out his willy.  I think boys can have discolouration in that area but i honestly couldn’t see anything unusual about his nether region!  he was my first boy though.  He started projectile vomiting at 10 days (must have still had lots of my good hormones still in him) which steadily got more often with each passing day.  He also didn’t gain any weight from birth ( I know they initially lose it for the first few days but it should be back on by the time you leave hospital) only steadily lost it until he was 500grams down on birth weight ( 1 pound).  So maybe you have to look for those signs and like Maria said make her doctor aware that his cousin has CAH.  Chances are though he is fine.  Best of luck and let us know how you get on.

Lisa D