INTELLIGENCE AND ACHIEVEMENT IN CHILDREN WITH EXTRA X-ANEUPLOIDY - A LONGITUDINAL PERSPECTIVE

Forty-seven children (35 male, 12 female) identified as having a super numerary X chromosome by neonatal screening were studied psychological ly from childhood to late adolescence. This paper compares their findi ngs relative to sibling controls on tests of intelligence and achievem ent collected over a 14-year period. Children with a supernumerary X c hromosome were found to score consistently below controls on Verbal IQ and subtests comprising the Verbal Comprehension factor but they did not differ on Performance IQ, which was in the normal range. At all ag es, they showed poorer reading and arithmetic achievement; relative ri sk for reading and arithmetic impairment was 2.6 and 2.6 in males and 1.1 and 1.7 in females. Males with an extra X chromosome were more lik ely to receive special education than females, who more often failed a grade. Academic achievement was not affected in aneuploid children wi th higher levels of intelligence. Overall, these results suggest milde r impairment than previously reported, particularly among trisomy X fe males. (C) 1995 Wiley-liss, dInc.