Psychiatric disorders associated with fragile X in the young female

Seventeen females with the fragile X mutation and 17 non-fragile X females group-matched on age (range 4 to 27 years), IQ (range 34 to 126), and socioeconomic status were compared on Diagnostic and Statistical Manual of Mental Disorders (3rd ed, revised) criteria for selected psychiatric disorders. Additional comparisons were made on level of social development and parent and teacher ratings of maladaptive behaviors. Correlations of genetic testing data with psychiatric and behavioral variables were investigated. Consistent with hypotheses, females with the fragile X mutation showed a greater frequency of avoidant disorder and mood disorders compared with control subjects. Females with the fragile X mutation also showed greater frequency of stereotypy/habit disorder when compared with control subjects. Contrary to predictions, females with the fragile X mutation did not show higher frequencies of attention deficit hyperactivity disorder or undifferentiated attention deficit. They showed greater deficits in their interpersonal socialization skills and were rated by their parents and teachers as significantly more withdrawn and depressed when compared with control subjects. The size of the DNA insertion associated with the genetic abnormality was correlated with IQ, severity of attention problems, and anxiety/withdrawal symptoms. Evidence from this study points to an association between a specific genetic syndrome and characteristic developmental and psychiatric difficulties. Implications for the clinician are discussed.