Delayed diagnosis of fragile X syndrome--United States, 1990-1999.

Fragile X syndrome (FXS) is the leading cause of inherited mental retardation, affecting approximately 50,000 persons in the United States. FXS occurs when a mutation on the X chromosome is passed from mother to child. Preliminary data suggest that children affected by FXS experience a delay in diagnosis, a pattern common to other single-gene disorders. The molecular test used to definitively diagnose FXS became available in 1991. The first indication of FXS within a family is usually the diagnosis of FXS in a child. Although no proven treatments exist for FXS, prompt diagnosis enables children to receive early intervention services and families to receive genetic counseling. To assess the timing of a diagnosis of FXS in an affected child and genetic counseling for the family, the Frank Porter Graham Child Development Institute (University of North Carolina at Chapel Hill) conducted a survey during August-October 2001 of 140 parents whose first child affected by FXS was born and had the condition diagnosed during 1990-1999. This report summarizes the results of that survey, which indicate that approximately half of the families did not learn the diagnosis for more than a year after first concerns about their child's development or behavior, and half reported having subsequent pregnancies before FXS was diagnosed in their first child. These findings emphasize the importance of increased opportunities for early diagnosis so children and families can receive all possible benefits, including genetic counseling and intervention services.