Testing the FMR1 Promoter for Mosaicism in DNA Methylation among CpG Sites, Strands, and Cells in FMR1-Expressing Males with Fragile X Syndrome
2011

DNA Methylation Mosaicism in Fragile X Males

Sample size: 9 publication 10 minutes Evidence: moderate

Author Information

Author(s): Reinhard Stöger, Diane P. Genereux, Randi J. Hagerman, Paul J. Hagerman, Flora Tassone, Charles D. Laird

Primary Institution: University of Washington

Hypothesis

Are certain types of DNA methylation patterns on heavily methylated promoters permissive of RNA transcription?

Conclusion

The study found that cryptic inter-cell mosaicism in DNA methylation can account for the presence of FMR1 mRNA in some individuals with Fragile X Syndrome.

Supporting Evidence

  • DNA samples from males with Fragile X Syndrome showed significant levels of FMR1 mRNA despite high methylation.
  • Two of the four FMR1-expressing males had unmethylated FMR1 alleles.
  • The study used advanced techniques to detect different types of DNA methylation mosaicism.

Takeaway

Some boys with Fragile X Syndrome can still make a protein called FMR1 even if their DNA is mostly turned off, which is surprising.

Methodology

The study used hairpin-bisulfite PCR to collect and assess double-stranded DNA methylation patterns.

Potential Biases

There is a risk of bias in PCR amplification favoring methylated alleles.

Limitations

The study was limited by the small sample size and the potential for undetected unmethylated alleles.

Participant Demographics

The study involved nine males with full mutation alleles of the FMR1 gene.

Statistical Information

P-Value

p<0.0001

Statistical Significance

p<0.0001

Digital Object Identifier (DOI)

10.1371/journal.pone.0023648

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