Effect of elevated blood tyrosine on subsequent intellectual development of premature infants

Sixty-five premature infants were examined neurologically and psychometrically duringtheir second year of life. When the neurologic status of infants who had marked tyrosinemia during their neonatal period was contrasted with that of infants whose tyrosine level remained below 15 mg. per cent, no significant difference could be detected. Although the percentage of infants with deviational I. Q. scores between 90 and 70 was significantly greater for the high tyrosine group, These differences disappeared when a deviational I. Q. score corrected for the postconceptual age was used.