Evaluation of school children at high risk for fragile X syndrome utilizing buccal cell FMR‐1 testing

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Abstract
We describe a pilot project utilizing saliva to identify the FMR‐1 mutation in high‐risk special education students from four public school districts in Colorado. The program included presentations to special education teachers regarding fragile X syndrome, parental consent for testing, completion of a behavior checklist by the teachers, identification of special education students at high risk for fragile X syndrome, subsequent brief examination of face and hands, collection of a saliva sample by either Gatorade swish or brushing of the inside of the cheek, and analysis for the FMR‐1 mutation by PCR. Equivocal samples were studied by direct DNA testing using Southern blot analysis, and abnormal results were confirmed by a blood analysis for the FMR‐1 mutation. Mutant individuals received genetic counseling and medical and educational assessments to optimize treatment and intervention. This pilot project was met with enthusiasm by the schools. Of the first 439 students evaluated, 68% were male with an average age of 7.75 years; 13% were mentally retarded or autistic. Most students referred for the evaluation were learning disabled (51%) and/or had an Attention Deficit Hyperactivity Disorder (ADHD) (35%). The overall prevalence of the FMR‐1 mutation was 5 of 439 or 1.1%. This relatively low yield is probably due to the high number of non‐retarded but learning disabled students tested. Of the mentally retarded patients tested, 3.5% were positive for the FMR‐1 mutation; however, of the non‐retarded or learning disabled patients, only 0.79% were FMR‐1 positive. The high‐risk criteria have been strengthened with a focus on mentally retarded individuals in an effort to increase our yield of affected individuals in the future.