November 1988

Institutional Screening for the Fragile X Syndrome

Author Affiliations

From the Child Development Unit (Dr Hagerman and Mr Jackson), Division of Genetics (Mss Berry and Smith), and the Cytogenetic Laboratory (Dr McGavran), The Children's Hospital, Denver; the Departments of Pediatrics (Dr Hagerman) and Pathology (Dr McGavran), University of Colorado Health Sciences Center, Denver; the Sewall Rehabilitation Center, Denver (Dr Hagerman); and the Wheat Ridge (Colo) Regional Center (Ms Campbell).

Am J Dis Child. 1988;142(11):1216-1221. doi:10.1001/archpedi.1988.02150110094028

• Cytogenetic screening of mentally retarded patients for the fragile X (fra[X]) chromosome is helpful in identifying individuals who could benefit from genetic counseling and treatment. Previous studies have demonstrated a prevalence of the fra(X) syndrome as high as 6% in institutionalized retarded males. The physical and behavioral predictors of positive findings from cytogenetic testing have not been clarified, since many features of the fra(X) syndrome are found in other retarded populations. We performed physical and cytogenetic examinations on 440 patients at the Wheat Ridge (Colo) Regional Center. Twenty-eight (6.3%) demonstrated abnormal karyotypes. Seventeen of these were autosomal abnormalities or sex chromosome aneuploidies and 11 demonstrated the fra(X) chromosome (seven males, four females). In males, the physical features that were predictive of the fra(X) syndrome included the combination of ear lengths of 7.0 cm or greater, macroorchidism of 30 mL or greater, and the presence of hand calluses or lesions secondary to hand biting. The fra(X) chromosome was not seen in spastic quadriplegic patients. All seven males with the fra(X) syndrome were detected among the 141 ambulatory males who resided in the highest functioning units at this institution.

(AJDC 1988;142:1216-1221)