phenylalanine hydroxylase https://ghr.nlm.nih.gov/gene/PAH https://ghr.nlm.nih.gov/gene/PAH https://ghr.nlm.nih.gov/gene/PAH https://ghr.nlm.nih.gov/gene/PAH phenylalanine hydroxylase https://ghr.nlm.nih.gov/gene/PAH https://ghr.nlm.nih.gov/gene/PAH https://ghr.nlm.nih.gov/gene/PAH phenylalanine hydroxylase