Development of language in Rett syndrome.
Ninety-nine cases of Rett syndrome (RTT) diagnosed clinically (age range 3 years 6 months to 29 years 9 months) were evaluated for the ability of language. The presence of meaningful words, vocabularies, and ages at the start and disappearance of speech were assessed. Phenotype/genotype correlation was evaluated in 22 cases in whom mutations of the genes of methyl-CpG-binding protein 2 (MECP2) existed. Fifty-five cases (55.5%) could speak some words, and of them eight cases (14.5%) spoke two-word sentences. No case had more than 40 words. The vocabularies were mainly bilabial words, known as the characteristics of the initial words in normal children. They began to utter a word between 12 and 48 months, and most of them (85.4%) before 20 months. Those who spoke two-word sentence(s) began to utter a word earlier (10.4+/-3.7 months) than others (17.1+/-9.8 months). Thirty-three cases lost their word(s) in 12-36 months. Among 22 gene-proven cases two cases with mutation of R133C and two cases with R294X had word(s), but another two cases with T158M had not. In RTT a delay in the neuronal systems involved in normal speech development was suggested and its severity seemed to depend on the loci of mutation.
Uchino
J
J
Segawa Neurological Clinic for Children, 2-8 Surugadai, Kanda Chiyodaku, 101-0062, Tokyo, Japan.
Suzuki
M
M
Hoshino
K
K
Nomura
Y
Y
Segawa
M
M
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D002868:Chromosomal Proteins, Non-Histone; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology*; D051783:Methyl-CpG-Binding Protein 2; D008875:Middle Aged; D012097:Repressor Proteins; D015518:Rett Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology*; D013060:Speech / Q000502:physiology
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C497392:MECP2 protein, human; D051783:Methyl-CpG-Binding Protein 2; D012097:Repressor Proteins