Methylation specific PCR (MS-PCR) is a technology for a sensitive detection of methylation in the gene. This assay was developed for diagnosis of methylation-related diseases including fragile X syndrome (FXS), the most common X-linked mental retardation caused by a CGG trinucleotide repeat expansion. Affected individuals (full mutation, FM) have CGG greater than 200 repeats, while normal individuals and premutation (PM) carriers have 6-54 and 55-200 repeats, respectively. Only FM individuals are correlated with methylation of the gene. The authors tested this assay on known 35 DNA samples (15 normal, 2 PM and 18 FM) and a prospective study of 60 males referred for FXS screening in Songklanagarind hospital. In addition, the authors tested on 2 prenatal cases. All results were corresponded to PCR for CGG repeats and/or Southern blot analysis. The authors concluded that MS-PCR provides an accurate method for methylation detection of FXS.

Keywords: Methylation specific PCR, Mental retardation, FMR1 gene