Rett

Incidence

 * Almost exclusively females
 * lethal in males

Molecular Etiology

 * MECP2 on Xq28
 * Wide Presentation = X-Inactivation imbalances
 * MECP2 duplication syndrome in males
 * A140V mutation associated with X-Linked Intellectual Disability in males
 * Atypical Rett: FOXG1 on Chromosome 14
 * earlier onset
 * de novo

Craniofacial Features

 * acquired microcephaly (5-48 months), decelerated head growth

Neurological

 * neurodegeneration starting around 5-6 months
 * loss of purposeful hand movements around 5-30 months
 * stereotypical hand-wringing movements
 * autism


 * ataxia
 * Intellectual Disability = Severe, especially expressive & receptive language