Prevalence of Rett and related disorders

Rett Syndrome is classified as an autistic spectrum disorder along with autism, pervasive developmental delay, Asperger’s Syndrome (high functioning autism) and childhood disintegrative disorder.  (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition – Revised
(DSM-IV-R) 

In February of 2007 the Centers for Disease Control and Prevention (CDC) reported that the average prevalence of autism spectrum disorders in the United State is 1 in 150 children.  Currently, over half a million children have a formal diagnosis of autism. The Autism Society of America predicts that the number will reach 4 million during the next decade.

The incidence of Rett Syndrome is estimated at 1 in 10,000 females; in the United States approximately 30,000 children and women affected (similar numbers to ALS, Huntington's, and Cystic Fibrosis).  Rett Syndrome is classified as a “rare disease” (by definition, less than 200,000 affected individuals in the US) by the Office of Rare Diseases of the National Institutes of Health.  This designation qualifies the condition for orphan drug status with favorable tax deductions and marketing exclusivity on a drug for an extended time period.

We now know that MECP2 duplications in males lead to a distinct neurological disorder with immune system complications. Geneticists suspect that MECP2 duplications may be a frequent cause of severe mental retardation in males. In fact, "MECP2 duplication syndrome” may be more common than Rett Syndrome.

With the recent knowledge that MECP2 mutations and duplications are found in a variety of disorders it is clear that research aimed at developing therapies specific to this gene will have an impact reaching far beyond Rett Syndrome. It has become evident that the number of individuals with "MECP2 Spectrum Disorders” who stand to benefit from MECP2 targeted therapies is far greater than originally suspected.

Banner image - Mouse neurons from the nodose ganglia (part of the vagus nerve). MECP2 stains green. Photography courtesy of David Katz/Journal of Neuroscience.