Betty S. Sutherland

A syndrome of phenylketonuria with normal intelligence and behavior disturbances

Summary 1. Two patients with biochemical characteristics of phenylketonuria have been described, one with normal and the other with nearly normal mental ability. 2. On preliminary examination a previously unreviewed psychological and psychomotor symptom complex common to both patients was recognized, which made diagnosis possible despite normal mental capacity. 3. A phenylalanine-restricted diet employed in treatment of one patient brought about alleviation of psychomotor and psychological agitation, suggesting that dietary therapy in the older phenylketonuric child may be beneficial. 4. There appears to be a definite relationship between I.Q. and serum phenylalanine concentration in these 2 children with normal and nearly normal intelligence. 5. The diagnosis of phenylketonuria in a child with normal mental ability may lead to recognition of families in which the abnormal gene might not otherwise have been discovered.

Phenylketonuria: Intellectual Developmental and Early Treatment

Treatment of eight children with phenylketonuria diagnosed before the age of 3 months has resulted in average or above average intellectual development similar to that of their parents and unaffected sibs. The eight children represent all early treated cases above age 3 years in this program. Late‐treated, or untreated, affected children in the same eight families show marked intellectual deficits compared with their unaffected sibs, early‐treated sibs and parents. Intellectual deficits were not found in the early‐treated children as compared with their unaffected sibs. The proportion of serum‐phenylalanine levels above or below certain points did not séem to offer a sufficient explanation for the differences in intellectual development noted in the early‐treated children.

Serum Amino Acid Concentrations during Pregnancy of Women Heterozygous for Phenylketonuria

Increased concentrations of phenylalanine were found in blood specimens from pregnant women who were heterozygous for phenylketonuria, but the concentration differences between normal controls, nonpregnant heterozygous, and pregnant heterozygous, and pregnant heterozygous women were small. Phenylalanine concentrations in cord blood were in the same range as in maternal blood at time of delivery. Phenylalanie concentrations in the carrier do not rise sufficiently during pregnancy to harm the infant in utero.