A process approach to describing mathematics difficulties in girls with Turner syndrome.

OBJECTIVE To expand on previous reports of mathematics difficulty in girls with Turner syndrome (TS). METHODS Mathematics performance was examined by evaluating the types of errors made on mathematics achievement subtests by 29 girls with TS, 26 girls with fragile X syndrome (another genetic condition associated with mathematics difficulty), and 41 girls with neither disorder. Correlations between mathematics achievement scores and measures of IQ, attention, and visuospatial skills were also examined. RESULTS Relatively low mathematics achievement was evident in girls with TS before 10 years of age, and a higher percentage of girls with TS made operation (57%) and alignment (48%) errors on a mathematics calculations test than did girls with fragile X syndrome (19% and 14%, respectively). No group differences were found for procedural or multiplication table errors. Girls with TS attempted more "unfamiliar" problems than did girls with fragile X syndrome or girls in the comparison group. Mathematics achievement scores in girls with TS were positively correlated with Judgment of Line Orientation and Wechsler Intelligence Scale for Children-Revised Third Factor scores; these correlations differed from those in the other groups. CONCLUSIONS The qualitative group differences observed further support the concept of specificity of the TS phenotype and illustrate the importance of a process approach to assessment.