Atypical Rett syndrome (Q101742)

Atypical Rett syndrome is a neurodevelopmental disorder in which patients don't fulfill the diagnostic criteria for typical Rett syndrome. Subvariants include: early-onset seizure type (Hanefeld variant) with seizures in the first months of life with subsequent development of Rett features; congenital variant (Rolando variant), the most severe form, with onset of classic Rett features during the first three months of life; 'forme fruste', a milder variant with onset in early; late childhood regression form with a more gradual and later onset regression of language and motor skills; preserved speech variant (Zappella variant) with recovery of some verbal and manual skills.