-Rett syndrome (RS) is a neurodevelopmental disorder, preferentially found in females and specifically involving the functions on which intelligence and its expression depend -learning, hand use and speechleaving many others intact. Mutations have been identified at Xq28 on the MECP2 gene (methyl-CpG 2), which selectively silences the expression of other genes whose location is still unknown. This is a study on clinical, diagnostic and epidemiological aspects of RS in a Brazilian sample. It included 33 female patients with chronic encephalopathy without known etiology. RS was diagnosed in 24 patients (72.7%): 17 (70.8%) had classical RS; 5 (20.8%), atypical RS and 2 (8.4%), potential RS. In 9 girls clinical data and/or laboratory studies excluded diagnosis of RS. Among the atypical RS patients, 4 were form fruste and one, congenital form. Among the girls with other encephalopathies, cerebral malformation was the most frequent finding.KEY WORDS: Rett syndrome, chronic encephalopathy, differential diagnosis.
Delineação da síndrome de Rett, forma clássica e variantes: diagnóstico diferencialRESUMO -Síndrome de Rett (SR) é desordem do neurodesenvolvimento que afeta preferencialmente meninas e envolve especificamente funções cognitivas -aprendizado, habilidade manual e linguagem -deixando outras intactas. Foram identificadas mutações no gene MECP2 (Metil-CpG 2) localizado no Xq28, que silencia seletivamente a expressão de outros genes que aguardam identificação. Este estudo baseia-se em aspectos clínico-diagnósticos e epidemiológicos da SR numa casuística brasileira. Foram estudadas 33 crianças do sexo feminino portadoras de encefalopatia crônica sem evidência de etiologia para o quadro. Em 24 pacientes (72,7%)