Fragile X Syndrome is the leading cause of autism and intellectual disability and is caused by the loss of a certain protein's function. This protein is known as fragile X mental retardation protein, or FMRP. In mice this protein results in changes of gene expression and chromatin regulation, and the synthesis of various proteins that control gene expression in ht brain. One of such proteins, Brd4, without the expression of FMRB begins to mess with the expression of other genes.
Using this knowledge, scientists were able to inhibit Brd4 with a drug. This alleviated many of the changes and symptoms associated with Fragile X Syndrome. With this knowledge, we could target proteins to treat this disorder and similar ones.
Healthy mouse brain on top with Brd4 being regulated, vs mouses Brian with Fragile X Syndrome which cannot regulate Brd4.