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Etymology: Andreas Rett, Austrian physician, 20th century
a pervasive developmental disorder affecting the gray matter of the brain, occurring exclusively in females and present from birth. It is progressive and is characterized by autistic behavior, ataxia, dementia, seizures, and loss of purposeful use of the hands, with cerebral atrophy, mild hyperammonemia, and decreased levels of biogenic amines. Also called cerebroatrophic hyperammonemia.