How common is profound deafness with PTPN11 mutation? Through the Genome1000 project the connexion 26 gene mutation was also picked up in my son, of which I am a carrier of the same gene but not my husband. Which gene is more likely to have caused my son to be born profoundly deaf in addition to all the other typical PTPN11 traits?

Connexin 26 should only cause deafness if the child has a double dose of the abnormal gene and therefore it is unlikely to be due to the connexin 26 in your son. Deafness does occur in Noonan syndrome especially when associated with multiple freckles or lentigines, but we still do not know why deafness only affects a few children with Noonan /PTPN11. In theory it may be when PTPN11 interacts with other genes but I have not seen any evidence to support this, so I think the connexin 26 is coincidental.