Cause

The leading cause of RTT is sporadic mutations in a gene called MECP2, located on the X chromosome. Studies have shown that more then 95% of mutations originate from a mutated sperm.

The MECP2 gene makes a protein, also called MeCP2, believed to play a pivotal role in silencing other genes. Scientists suspect that the inability to shut down specific genes causes the cascade of symptoms seen in RTT.

How mutations in MeCP2 lead to RTT is not well understood but is the focus of intense research. Experiments suggest that MeCP2 is not required for early brain development but rather is essential for the maintenance of maturing brain cells (neurons).