Early development of children with sex chromosome aberrations.

A prospective study was made of 42 children who were found at birth to have sex chromosome aberrations. The mean developmental quotient of the XXY and XXX groups was in the dull-normal range, whereas developmental quotients of 3 XYY children were low normal. The commonest deficits were in language and gross motor skills, with highest incidence in the XXX group. Many of the children had behavior problems, but no specific pattern was associated with an individual chromosome aberration. The XXX group experienced a linear growth spurt after 4 years of age. With one exception there were only mild dysmorphic features, none of them specifically associated with any subgroup. Of 17 children followed up to school age, almost two thirds evidenced learning and/or behavior problems. There was a high incidence of birth problems particularly in XXX children (seven of ten), and of social problems, psychiatric illness and learning difficulties in their families. In 14 cases, the parent-child relationship was disturbed, resulting in behavior problems. These findings make it improbable that the children's generally poor developmental and behavioral performance were solely attributable to their chromosomal constitution.