Neurodevelopmental assessment of early treated children with phenylketonuria: insights from Griffith III scales.

Unlabelled: Neonatal screening of phenylketonuria (PKU) and early treatment are fundamental to prevent mental retardation in children. Unfortunately, it has been observed that some neurological sequelae may still be exhibited despite these preventive strategies. Assessment of the neurodevelopment of early treated children may aid in understanding the devastating effect of PKU on the developing brain, so this study aimed to investigate the neurodevelopmental outcome of early-treated children with PKU using Griffiths-III developmental scales. We conducted an observational single-center case-control study on a total of 60 children.  We compared the neurodevelopmental profile of two groups of children (PKU group = 30 and healthy control group = 30) using Griffiths-III developmental scales. Also PKU children were divided into two subgroups according to their phenylalanine level: controlled and uncontrolled. There were significant decreases in the mean of developmental quotients (DQs) of Griffiths-III subscales A, B, C, D, and general development of PKU group. While there was insignificant difference in the DQ of subscale E (gross motor) among the two groups, there was a significant difference between the two PKU subgroups regarding the developmental quotient of subscales A, B, C, E, and general development. Also, there was a statistically significant correlation between phenylalanine (Phe) levels and the mean of DQs of all Griffiths-III subscales.

Conclusion: Early- treated PKU children are at risk of poor neurodevelopmental outcome even if their gross motor function is normal and this defect is negatively correlated with phenylalanine levels.

What Is Known: • PKU is an inborn error of metabolism that causes mental retardation if not treated early. • Neonatal screening and early treatment prevent mental retardation.

What Is New: • Despite neonatal screening and early treatment, PKU children still exhibit mental function impairment. • The Griffiths III developmental scales is the first time to be used to assess mental functions in PKU children.