title: Mild hyperphenylalaninemia and heterozygosity of the phenylalanine hydroxylase gene.
abstract: Newborn screening for phenylketonuria (PKU) is now the standard of practice. Initial phenylalanine blood levels of 240 mumol/L result in referral of affected newborns to medical facilities experienced in caring for patients with metabolic disorders. This case report concerns a female infant born in 1976 with a presumptive positive PKU screening test on the third day of life of 240 mumol/L phenylalanine. Follow-up levels while the mother was breast feeding on the sixth day of life were 324 and, on the 27th day, 312 mumol/L. She was subsequently lost to follow-up at age 11 years, but returned at 19 years of age due to pregnancy, with a blood phenylalanine level of 132 mumol/L. Mutation studies then were performed documenting that she was a carrier for the phenylalanine hydroxylase gene and did not have hyperphenylalaninemia. The mother's parents and the infant were also genotyped confirming heterozygosity. The infant on follow-up is completely normal, following a normal pregnancy.
authors.affiliation: Division of Medical Genetics, Childrens Hospital, Los Angeles, California 90027, USA.
authors.forename: R
authors.initials: R
authors.lastname: Koch
authors.forename: F
authors.initials: F
authors.lastname: Güttler
authors.forename: P
authors.initials: P
authors.lastname: Guldberg
authors.forename: B
authors.initials: B
authors.lastname: Rouse
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006580:Genetic Carrier Screening; D006801:Humans; D007231:Infant, Newborn; D010649:Phenylalanine / Q000097:blood*; D010651:Phenylalanine Hydroxylase / Q000235:genetics*; D017042:Phenylketonuria, Maternal / Q000235:genetics*; D011247:Pregnancy
chemical_list: D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase