In 1992, during some research on DNA methylation, Bird discovered the MeCP2. Since then, the chromosomal protein MeCP2 is being researched non-stop as it is the cause for Rett syndrome.
Rett Syndrome gene therapy research on mice
In 2007, Prof. Bird published in "Science" magazine an article that shows it is possible to the symptoms of Rett syndrome in mice. Rett syndrome is caused by mosaic expression of mutant copies of the X-linked MECP2 gene in neurons. Bird discovered that neurons do not die. This was a massive discovery since it suggested that this is not a neurodegenerative disorder. The research that was made on a mice model showed robust phenotypic reversal.
This evidence implies that reactivation of Mecp2 in young and adult mice can reverse characters of Rett pathology. The research data show that the absence of MeCP2 protein does not irreversibly damage neurons, which implies that Rett is indeed reversible.
The restoration of neuronal function by new expression of MeCP2 suggests that the molecular MeCP2 activity can function when restored later.
The bottom line of the study shows that Rett-like neurological defects due to the absence of the mouse Mecp2 gene can be rescued by late restoration of the gene. The researchers suggest they established the principle of reversibility in a mouse model.
Thus, it raised the probability the same can happen for human Rett syndrome symptoms and that they not permanent and can be reversed and cured.
Below is a video from Bird's lab that shows a mouse model before reversal.
And here is a video of the mouse model after the reversal.