What is methylation?
Methylation is a process in which a chemical group, called a methyl group, gets added to the DNA. When enough methyl groups are added to the DNA, the gene gets turned off. When methyl groups are removed, the gene gets turned on. This is a normal process and many of our genes are controlled by methylation. However, in fragile X syndrome, the methylation of the FMR1 gene turns the gene off when it should be turned on. When FMR1 is turned off, its protein is not made, and you see the features of fragile X syndrome. When someone with fragile X syndrome has methylation mosaicism, not all cells will have the FMR1 gene turned off by methylation. Some cells may have it partially turned off, and some cells may have the FMR1 gene turned on. 4. I heard only boys have fragile X syndrome. Why does my daughter have it also? Girls can also have fragile X syndrome even though they have two “X” chromosomes.
Methylation is a process in which a chemical group, called a methyl group, gets added to the DNA. When enough methyl groups are added to the DNA, the gene gets turned off. When methyl groups are removed, the gene gets turned on. This is a normal process and many of our genes are controlled by methylation. However, in fragile X syndrome, the methylation of the FMR1 gene turns the gene off when it should be turned on. When FMR1 is turned off, its protein is not made, and you see the features of fragile X syndrome. When someone with fragile X syndrome has methylation mosaicism, not all cells will have the FMR1 gene turned off by methylation. Some cells may have it partially turned off, and some cells may have the FMR1 gene turned on. 4. I heard only boys have fragile X syndrome. Why does my daughter have it also? Girls can also have fragile X syndrome even though they have two “X” chromosomes. The reason is that they have a full expansion on one chromosome and a normal repeat section (in
