Clinical Genetic Testing for Fragile X Syndrome by Polymerase Chain Reaction Amplification and Southern Blot Analyses

Methods Mol Biol. 2019:1942:11-27. doi: 10.1007/978-1-4939-9080-1_2.

Abstract

Fragile X syndrome (FXS) is characterized by mental retardation and in the vast majority of cases it is caused by expansion of CGG trinucleotide repeats in the 5' untranslated region (or UTR) in the FMR1 gene on the X chromosome. The size and methylation status of CGG repeats are correlated with the clinical phenotype of FMR1-related disorders. The methods used for clinical genetic testing of FXS include polymerase chain reaction (PCR) amplification and Southern blot analyses, which effectively detect alleles with repeats in the normal, intermediate, premutation, and full mutation size ranges, as well as the methylation status of FMR1 promoter region.

Keywords: CGG repeat; FMR1; Fragile X syndrome; Methylation PCR; Southern blot; Triplet repeat-primed PCR.

MeSH terms

  • Blotting, Southern / methods*
  • DNA Methylation
  • Female
  • Fragile X Mental Retardation Protein / genetics*
  • Fragile X Syndrome / diagnosis*
  • Fragile X Syndrome / genetics
  • Genetic Testing*
  • Humans
  • Male
  • Mutation*
  • Polymerase Chain Reaction / methods*
  • Trinucleotide Repeats

Substances

  • FMR1 protein, human
  • Fragile X Mental Retardation Protein