Rett's Syndrome

Most people have never heard of Rett syndrome because it has only recently been formally recognized. In fact, it wasn't until 1983 that the condition known as Rett syndrome first appeared in medical literature. Those with Rett syndrome were likely once misdiagnosed with autism or cerebral palsy.

Rett syndrome is a condition caused by a gene mutation (MECP2) that occurs before birth. The discovery of the Rett syndrome gene was announced on October 1, 1999 by researchers at Baylor College of Medicine in Houston, Texas.

Females have two X chromosomes (XX) and males have one X chromosome and one Y chromosome (XY). The mutation which causes Rett syndrome (MECP2) is on the X chromosome. So, if the mutation causing Rett syndrome appears on one X, females are able to survive because they still have another X. Males, on the other hand, have only one X (XY). If the mutation appears on a male's X chromosome, he would most likely not survive to birth.

This has led researchers to speculate that a male fetus that survives to birth with the MECP2 mutation would have far more severe symptoms than a female fetus--to the point that the condition would probably not even be recognized as Rett syndrome.