MATERNAL PHENYLKETONURIA AND HYPERPHENYLALANINEMIA. A PROSPECTIVE STUDY

Abstract

The possible effects of increased blood phenylalanine concentrations on the fetus are of considerable importance, particularly since many girls successfully treated for phenylketonuria (PKU) will shortly become of childbearing age. We have studied prospectively 17 offspring of 8 women who have had varying degrees of hyperphenylalaninemia (HPHE). These women have been discovered as a result of routine screening of an offspring, either of cord blood or of newborn blood. None has received any dietary therapy. Group I includes 3 women with mild HPHE (blood Phe 3-6 mg%) and Group II includes 2 women with intermediate HPHE (blood Phe >6-12 mg%; occasional mild phenylpyruvic aciduria). All 11 offspring are normal. Group III includes one woman with “atypical” PKU (blood Phe >12-15 mg%; moderate phenylpyruvic aciduria). Though she has a slightly higher IQ than her non-PKU sister (78 vs. 71), her 3 offspring have consistently lower IQs than her sister's 3 offspring. Group IV includes two women with “classical” PKU. In one, who is retarded (IQ 56), twin offspring are mentally retarded at age 4 yr. (IQs 67 and 61). In the other, who is dull normal, the infant offspring is developmentally slow at age 1 year. Neither microcephaly nor congenital anomalies has been noted. It would seem that the degree of fetal brain damage from maternal PKU and HPHE may be proportional to the maternal blood Phe level beginning at >12 mg/100 ml.

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