Question

Normally the FMR1 locus does not have DNA methylation in the gene or promoter region. However, copies of the FMR1 gene with mutation length CGG repeats are modified; they have DNA methylation extending into the promoter region. This leads to ____________ expression of that copy of the FMR1 gene.

no change in

decreased

increased

Answer 1

FMR1 gene is located on X chromosome,has trinucleotide sequence CGG, located in the first Exon of the gene which function as promoter.

It has grey zone alleles 45-54

FMRT goue STRUCTURE a) grey Loue allele (649)45-54 AT Methylaliow; neo Normal Phenotype VIE Transcription وا b) are mutation allele Methycation : No 171111111 55-200 ATG Phenotype: large normal transcription e) full mucation (cee ) ATG. 18 F//////////// transcription Melhytalion Rosent Phenotype afected > 200 MO

Permutations alleles 55-200

Full mutations alleles above 200 CGG repeats

Methylation of the CGG expansion is an epigenetic process which involves methyl group added to DNA molecule

DNA Methylation of mutation allele of FMR1gene leads to decreased or silenced FMR1 transcription resulting in deficiency or absence of FMR1 protein which is responsible for synaptic development and plasticity in brain.