Optimization of polymerase chain reaction assay combined with capillary electrophoresis to detect the pre- and full mutation of FMR1 gene

Abstract

To develop an efficient, high resolution PCR assay suitable for detection of the (CGG)n repeats of the fragile X mental retardation 1 (FMR1) gene by optimizing the PCR system in combination with capillary electrophoresis. Three standard samples and twelve samples that were verified by Southern blot analysis including both male and female in the normal, pre- and full mutation range were used in this study to evaluate the enhanced PCR system. All amplicons were electrophoresed by agarose, polyacrylamide and capillary electrophoresis to compare the results. The enhanced PCR assay developed in this study was able to detect a full mutation with (CGG)n being larger than 260 repeats in a male. An expanded pre-mutation allele with (CGG)n as large as 183 repeats in a female was also amplified. The capillary electrophoresis method used in this study was able to distinguish two alleles with 1 CGG repeat difference and the results were reproducible. A high resolution PCR assay is developed, which is much more efficient than the general PCR systems. It is suitable for the clinical screening of FMR1 gene and will greatly reduce the number of Southern blot analysis needed in clinical application.