The behavioral profile of children aged 1–5 years with sex chromosome trisomy (47,XXX, 47,XXY, 47,XYY)

Children with SCT have an increased risk of suboptimal neurodevelopment. Previous studies have shown an elevated risk for neurobehavioral problems in individuals with SCT. However, not much is known about neurobehavioral problems in very young children; knowledge that could help with early identification of children at risk for suboptimal development, and that could help establish targets for early intervention. This study addressed the question of what the behavioral profile of children with SCT aged 1–5 years looks like. In total, 182 children aged 1–5 years participated in this study (N_SCT=87, N_{nonclinical controls} = 95). Recruitment and assessment took place in the Netherlands and the United States. The SCT group was recruited through prospective follow‐up (50%), information seeking parents (31%), and clinical referral (18%). Behavioral profiles were assessed with the child behavior checklist and the ages‐and‐stages social–emotional questionnaire. Levels of parent‐rated problem behavior were higher in children with SCT. Difficulties with overall social–emotional functioning were already present in 1‐year‐olds, and elevated scores were persistent across the full age range. Affective and pervasive developmental behaviors were seen in late toddlerhood and prominent at preschool age. Anxiety, attention deficit, and oppositional defiant behaviors were seen in preschool‐aged children. Within this cross‐sectional study, the developmental trajectory of affective, pervasive developmental, and oppositional defiant behaviors seemed to be different for SCT children than nonclinical controls. Collectively, these results demonstrate the importance of behavioral screening for behavioral problems in routine clinical care for children with SCT from a young age. Social–emotional problems may require special attention, as these problems seem most prominent, showing increased risk across the full age range, and with these problems occurring regardless of the timing of diagnosis, and across all three SCT karyotypes.