Causes

Rett syndrome is a rare genetic disorder. Classic Rett syndrome, as well as several variants with milder or more-severe symptoms, can occur based on the specific genetic mutation.

The genetic mutation that causes the disease occurs randomly, usually in the MECP2 gene. Only in a few cases is this genetic disorder inherited. The mutation appears to result in problems with the protein production critical for brain development. However, the exact cause is not fully understood and is still being studied.

Rett syndrome in boys

Because males have a different chromosome combination from females, boys who have the genetic mutation that causes Rett syndrome are affected in devastating ways. Most of them die before birth or in early infancy.

A very small number of boys have a different mutation that results in a less destructive form of Rett syndrome. Similar to girls with Rett syndrome, these boys will likely live to adulthood, but they're still at risk of a number of intellectual and developmental problems.