Background:Children with phenylketonuria of early onset under continuous treatment are considered at higher risk for psychological maladjustment than children without other chronic diseases. The aim of the present study was to evaluate the psychological adjustment of Lithuanian children with treated phenylketonuria and analyze it in the context of the psychological adjustment of their parents.Material/Methods: The parents of 37 early-treated children (age 4–14 years old) with phenylketonuria and of 37 matched controls were asked to fill out the Child Behavior Checklist and questionnaire on stress coping strategies. Parents of children with phenylketonuria answered a questionnaire on reactions to the child’s disease and its impact on the family.Results: Lithuanian children with treated phenylketonuria have significantly more emotional and behavioral problems than healthy controls. They are more withdrawn, anxious/depressed, have more social and attention problems. The higher rates of internalizing and total problems are related to parental maladjustment (feelings of guilt and anger) together with maladaptive (emotional) everyday stress coping strategies. These last two factors promote overindulging the child, which is also a predictor of psychological maladjustment in children with phenylketonuria.Conclusions: The already existing organic vulnerability may account for the greater susceptibility of children with phenylketonuria to psychological risk factors, as for example parental inability to cope adequately with everyday stress related to the demands of disease and its treatment.

Keywords: Adolescent, Child, Child, Child, Preschool, Chronic Disease - psychology, Family Health, Lithuania, Parents, Phenylketonurias - psychology, Questionnaires, Risk Factors, Risk Factors, Stress, Psychological, Adolescent, Child, Child, Preschool, Chronic Disease - psychology, Family Health, Lithuania, Parents, Phenylketonurias - psychology, Questionnaires, Risk Factors, Stress, Psychological