Social functioning among girls with fragile X or Turner syndrome and theirsisters

Social behaviors among two genetically homogeneous groups-girls with fragil e X (fraX) or Turner syndrome (TS)-were examined to address the role of fam ily environment versus biological determinants of social dysfunction in gir ls with these disorders. Using a sibling pair design, girls with fraX or TS were compared with their own sisters on measures of IQ and social function ing. The 8 girls with fraX and the 9 girls with TS had lower FSIQ scores an d higher ratings of social and attention problems relative to their own sis ters. Girls with fraX also had higher ratings of withdrawn behaviors, relat ive to their own sisters. The unaffected sisters were not rated as demonstr ating any difficulties in these areas, relative to controls. Correlations b etween problem ratings and FSIQ were not statistically significant. Althoug h these preliminary findings do not indicate a lack of familial impact on s ocial development in girls with either disorder, the results provide prelim inary evidence that social dysfunction reported for girls with fraX or TS c annot be attributed solely, nor primarily, to global aspects of the family environment.