Complex sentence: Fragile X Syndrome, an intellectual disability disorder, is caused by an increase from 50 to 200 CGG repeats within exon 13 of the FMR1 gene, inhibiting FMR1 transcription by increasing DNA methylation and other epigenetic heterochromatin modifications.
Split into simpler sentences: Fragile X Syndrome, an intellectual disability disorder, is caused by an increase from 50 to 200 CGG repeats within exon 13 of the FMR1 gene. This increase in repeats inhibits FMR1 transcription by increasing DNA methylation and other epigenetic heterochromatin modifications.