What Causes Rett Syndrome?
Most children with Rett syndrome have a mutation in a particular gene on the X chromosome. Exactly what this gene does, or how its mutation leads to Rett syndrome, isn't clear. It's believed that the single gene may influence many other genes involved in development.
Although Rett syndrome seems to be genetic, the faulty gene is almost never inherited from the parents. Rather, it's a chance mutation that happens in the girl's own DNA. No Rett syndrome risk factors have been identified, other than being female. There is no known method for preventing Rett syndrome.
When boys develop the Rett syndrome mutation, they die shortly after birth. Because boys have only one X chromosome (instead of the two girls have), the disease is more serious, and quickly fatal.