Abstract:Abstract: OBJECTIVE The analysis of 66 children with phenylketonuria was analyzed to provide reference for the prevention and treatment of phenylketonuria and genetic counseling. METHODS Through phenylalanine hydroxylase deficiency (PAH) gene detection and total exon sequencing, 66 children with phenylketonuria were analyzed. The intellectual development of children aged 0 to 6 years old was assessed by Developmental Behavioral Assessment Scale in Children Aged 0 to 6 Years (WS/T 580—2017) , and the intelligence assessment of children aged 6 years and above was performed. RESULTS A total of 40 phenylalanine hydroxylase gene mutations and 130 mutation sites were detected in 66 children with phenylacetonuria. Among them, the high-frequency gene mutation site was c.728G>A (25.0%), c.611A>G (7.7%), c.1068C>A (6.9%). The children in the substandard group had poor diet control, the phenylalanine blood value was unstable, beyond the ideal range, and could not follow the doctor's advice for review (low compliance). CONCLUSION 66 children had c.728G>A, c.611A>G, c.1068C>A. Poor diet control leads to children with phenylal⁃ anine over the ideal range, and they do not follow the doctors’ advice to review, which will affect their intellectual development.