Intellectual Development in 12-Year-Old Children Treated for Phenylketonuria

Colleen G. Azen, Richard Koch, Eva Gross Friedman, Stanley Berlow, James Coldwell, Wilma Krause, Reuben Matalon, Edward McCabe, Margaret O'Flynn, Raymond Peterson, Bobbye Rouse, C. Ronald Scott, Bernice Sigman, David Valle, Robert Warner

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


Intelligence and achievement test scores were evaluated for 95 12-year-old children with phenylketonuria who had begun dietary therapy during the neonatal period. Dietary control of blood phenylalanine below 900 μmol/L was maintained beyond age 10 years in 23 children; 72 others had blood phenylalanine persistently above that level at ages ranging from 18 months to 10 years. Test scores at age 12 years were negatively correlated with the age at initiation of diet and with blood phenylalanine levels from ages 4 to 10 years, and positively correlated with parent IQ scores and the age at loss of dietary control. Children who maintained phenylalanine levels below 900 μmol/L beyond age 10 years showed no deficits in test scores, except for arithmetic, the scores of which declined between ages 6 and 12 years in 90% of the children in this study. These data strongly support a recommendation that dietary restriction of phenylalanine should be maintained through adolescence.

Original languageEnglish (US)
Pages (from-to)35-39
Number of pages5
JournalAmerican Journal of Diseases of Children
Issue number1
StatePublished - Jan 1991
Externally publishedYes

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health


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