Rett's Disorder starts in baby girls who appeared totally normal at birth.  Boys are not affected.  It is a fairly common cause of severe mental retardation in girls affecting one in 10,000 births.  Head circumference at birth is normal and psychomotor development is normal until the 5th or 6th month of life.  Then head growth slows down.  There is a loss of purposeful hand skills over the next two years until a characteristic stereotyped hand-wringing or hand washing movement develops.  Interest in the social environment decreases during the same period.  Coordination of gait and trunk movements become difficult with severe psychomotor retardation.  There is also severe impairment of both expressive and receptive language development.  Severe or Profound Mental Retardation is usually present.  a seizure disorder is common and is treated with seizure medications.  The duration of the disease is lifelong with only small amounts of progress occurring with age. 

Rett's Syndrome MECP2 Gene Causes Some Schizophrenia and Autism: The gene for MECP2 is mutated in Rett Syndrome girls, a cause in mental retardation in 1/10,000 births. Earlier research suggested that the MeCP2 protein was responsible for making sure that genes the cell has marked with a molecular tag, called a methyl group, are silenced. The MeCP2 protein latches on to these methyl groups and prevents them from being translated into protein.  Cases of both classic autism and schizophrenia are caused by mutations in this gene. Neuron 7/18/02

MeCP2 Regulates the BDNF Gene: The BDNF gene is very active from the 6th to 18th month of life.  It is constantly turning on and off.  New research has discovered how it is turned off.  After the BDNF gene is methylated, MeCP2 binds to it, shutting the gene off -- but only temporarily. If the neuron cells are excited by any kind of environmental stimulus, MeCP2 immediately detaches, and the BDNF gene begins producing protein. When the stimulus disappears, MeCP2 re-attaches to BDNF, again locking the deadbolt until a neuronal stimulus starts the process again. One theory is that in Rett patients, mutations in MeCP2 impair its ability to regulate BDNF, and that BDNF's subsequent over-expression may cause Rett. However, BDNF is only one of approximately 300 genes that are controlled by neuronal activity, many of which also may be targeted by MeCP2. 11/4/03, Michael Greenberg, Harvard, and Rudolf Jaenisch, Whitehead Institute of Biomedical Research.