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Children with phenylketonuria (PKU) do not show significant birthweight differences compared to their siblings. This study suggests normal intrauterine growth for infants with classical PKU.
Area of Science:
- Medical Genetics
- Pediatric Development
- Metabolic Disorders
Background:
- Phenylketonuria (PKU) is a genetic disorder affecting metabolism.
- Previous reports suggested significantly lower birthweights in infants with PKU.
- This raised concerns about intrauterine growth in affected fetuses.
Purpose of the Study:
- To investigate intrafamily birthweight differences in siblings with and without PKU.
- To re-evaluate the impact of PKU on intrauterine physical growth.
- To address discrepancies in previous birthweight findings for PKU infants.
Main Methods:
- Analysis of birthweights within 40 sibships containing both affected and unaffected children.
- Calculation of weighted average intrafamily birthweight differences.
- Application of multiple regression analysis to adjust for potential confounding factors.
Main Results:
- The weighted average intrafamily difference in birthweight was 69 gm.
- The adjusted estimate for the birthweight difference between PKU children and siblings was -51 gm.
- These findings contradict earlier reports of substantial birthweight deficits.
Conclusions:
- The intrauterine physical growth of children with classical PKU is likely not adversely affected.
- The study's results support the assumption of normal fetal development regarding size in PKU.
- Further research may clarify the precise mechanisms influencing birthweight in PKU.
Abstract:
The assumption that children with phenylketonuria (PKU) develop normally until birth was brought into question by the recent report that PKU children weigh several hundred grams less at birth than their unaffected siblings. We have examined intrafamily differences in birthweight in 40 sibships with at least one affected and one unaffected child. The difference in mean birthweights computed by taking a weighted average of the intrafamily differences was 69 gm, and the adjusted estimate of the birthweight difference between children with PKU and their siblings, obtained from a fitted multiple regression function, is -51 gm. The findings are not consistent with the large difference in birthweight reported previously and are compatible with the assumption that the intrauterine physical growth of children with classical PKU is not adversely affected.