Rett syndrome is one of a group of disorders known as the MECP2 related disorders, caused by a change, or mutation, in the MECP2 gene on the X chromosome. This group of disorders includes classic Rett syndrome, variant Rett syndrome, mild learning disabilities, and rarely, autism. These conditions occur almost exclusively in females. When the same gene change occurs in a male it is usually either lethal or causes a severe neurological condition at birth.
About 1 in every 8,500 baby girls born has an MECP2 related disorder by the time they they turn 15.
This information was last updated in May 2020.