Inheritance
About 99% of people affected with RTT did not inherit this disorder. Instead, it is caused my a sporadic mutation of the MECP2 gene on the X chromosome. (See Cause) There are very few cases where more than one family member also have Rett Syndrome, but that is only 1% of people with RTT. Researchers have determined that RTT has an X linked dominate pattern. X linked means that the trait is located on the X chromosome, one of the sex chromosomes. This disorder is mainly found in females because they have two X chromosomes and most likely one of them does not have the mutation on it. Sadly in males, this disorder is more lethal. Most males will die at infancy, unless there symptoms are not to severe. But they will most likely die at a young age.