Etiology of Rett Syndrome

Rett syndrome (symbolized RTT) is X-linked dominant, affecting almost exclusively girls. Development is normal until 1 year of age, when language and motor milestones regress and acquired microcephaly is seen. Hand wringing and sighing are characteristic, and they develop autistic behavior. Rett syndrome is usually caused by a mutation in the gene encoding methyl-CpG-binding protein-2 (MECP2). MECP2 is found on chromosome band Xq28, near the long end of the X chromosome. Rett syndrome can also be caused by a mutation to the gene encoding cyclin-dependent kinase-like 5 (CDKL5). Rett syndrome affects 1 in every 12,500 female live births.