Maternal hyperphenylalaninemia
Overview
Maternal hyperphenylalaninemia: A rare disorder where a mother suffering from phenylketonuria during pregnancy can result in various birth abnormalities.
Symptoms
The list of signs and symptoms mentioned in various sources for Maternal hyperphenylalaninemia includes the 19 symptoms listed below: * Mental deficiency * Low I.Q. * Increased muscle tone * Pigeon-toed gait * Growth deficiency * Small head * Round face * Prominent glabella * Epicanthal folds * Short space between eyelids * Strabismus * Long philtrum * Underdeveloped philtrum * Thin upper lip * Small upturned nose * Maxillary hypoplasia * Mandibular hypoplasia * Congenital heart disease * Low birthweight
Causes
PKU is transmitted by an autosomal recessive gene on chromosome 12. Patients with this disorder have insufficient hepatic phenylalanine hydroxylase, an enzyme that acts as a catalyst in the conversion of phenylalanine to tyrosine. As a result, phenylalanine and its metabolites accumulate in the blood, eventually causing mental retardation if left untreated. The exact biochemical mechanism that causes this retardation is unclear. In the United States, this disorder occurs in 1 in approximately 14,000 births. (About 1 person in 60 is an asymptomatic carrier.) The gene is most common in Ireland, Scotland, Belgium, and West Germany and rare in Blacks, Asians, Native Americans, Finns, and Ashkenazi Jews.
Treatment
Treatment consists of restricting dietary intake of the amino acid phenylalanine to keep phenylalanine blood levels between 3 and 9 mg/dl. Because most natural proteins contain 5% phenylalanine, they must be limited in the child's diet. An enzymatic hydrolysate of casein, such as Lofenalac powder or Pregestimil powder, is substituted for milk in the diets of affected infants. This milk substitute contains a minimal amount of phenylalanine, normal amounts of other amino acids, and added amounts of carbohydrate and fat. Dietary restrictions usually continue throughout life. The special diet for PKU calls for careful monitoring. Because the body doesn't make phenylalanine, overzealous dietary restriction can induce phenylalanine deficiency, producing lethargy, anorexia, anemia, rashes, and diarrhea.