A Homogeneous Assay for Analysis of FMR1 Promoter Methylation in Patients with Fragile X Syndrome

Abstract
Background: Fragile X syndrome is caused by the expansion of a CGG trinucleotide repeat at the 5′ untranslated region of the fragile X mental retardation 1 gene (FMR1). When expanded to >200 repeats (full mutation), the repeat region and the adjacent promoter CpG island become hypermethylated, rendering FMR1 transcriptionally inactive. Conventional molecular diagnosis of fragile X syndrome involves determination of the CGG repeat number by Southern blot analysis.