Genome-wide analysis validates aberrant methylation in fragile X syndrome is specific to the FMR1 locus
- Equal contributors
1 Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA, 30322, USA
2 Departments of Human Genetics, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA
3 Departments of Biochemistry, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA
4 Departments of Pediatrics, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA
5 Current address: Department of Psychiatry, University of Wisconsin–Madison, Madison, WI, 53719, USA
BMC Medical Genetics 2013, 14:18 doi:10.1186/1471-2350-14-18Published: 29 January 2013
Fragile X syndrome (FXS) is a common form of inherited intellectual disability caused by an expansion of CGG repeats located in the 5′ untranslated region (UTR) of the FMR1 gene, which leads to hypermethylation and silencing of this locus. Although a dramatic increase in DNA methylation of the FMR1 full mutation allele is well documented, the extent to which these changes affect DNA methylation throughout the rest of the genome has gone unexplored.
Here we examined genome-wide methylation in both peripheral blood (N = 62) and induced pluripotent stem cells (iPSCs; N = 10) from FXS individuals and controls.
We not only found the expected significant DNA methylation differences in the FMR1 promoter and 5′ UTR, we also saw that these changes inverse in the FMR1 gene body. Importantly, we found no other differentially methylated loci throughout the remainder of the genome, indicating the aberrant methylation of FMR1 in FXS is locus-specific.
This study provides a comprehensive methylation profile of FXS and helps refine our understanding of the mechanisms behind FMR1 silencing.