Genetic causes of intellectual disability in a birth cohort: a population-based study.
Intellectual disability affects approximately 1-3% of the population and can be caused by genetic and environmental factors. Although many studies have investigated the etiology of intellectual disability in different populations, few studies have been performed in middle-income countries. The present study estimated the prevalence of genetic causes related to intellectual disability in a cohort of children from a city in south Brazil who were followed from birth. Children who showed poor performance in development and intelligence tests at the ages of 2 and 4 were included. Out of 4,231 liveborns enrolled in the cohort, 214 children fulfilled the inclusion criteria. A diagnosis was established in approximately 90% of the children evaluated. Genetic causes were determined in 31 of the children and 19 cases remained unexplained even after extensive investigation. The overall prevalence of intellectual disability in this cohort due to genetic causes was 0.82%. Because this study was nested in a cohort, there were a large number of variables related to early childhood and the likelihood of information bias was minimized by collecting information with a short recall time. This study was not influenced by selection bias, allowing identification of intellectual disability and estimation of the prevalence of genetic causes in this population, thereby increasing the possibility of providing appropriate management and/or genetic counseling.
Programa de Pós-Graduação em Saúde da Criança e do Adolescente, UFRGS, Porto Alegre, Brazil.|Faculdade de Medicina, Universidade Federal do Rio Grande (FURG), Rio Grande, Brazil.
Simone M
SM
Karam
Serviço de Genética Médica, HCPA, Porto Alegre, Brazil.|Programa de Pós-Graduação em Genética e Biologia Molecular, UFRGS, Porto Alegre, Brazil.
Mariluce
M
Riegel
Serviço de Genética Médica, HCPA, Porto Alegre, Brazil.
Sandra L
SL
Segal
Programa de Pós-Graduação em Saúde da Criança e do Adolescente, UFRGS, Porto Alegre, Brazil.|Serviço de Genética Médica, HCPA, Porto Alegre, Brazil.
Têmis M
TM
Félix
Programa de Pós-Graduação em Epidemiologia, UFPel, Pelotas, Brazil.
Aluísio J D
AJ
Barros
Programa de Pós-Graduação em Epidemiologia, UFPel, Pelotas, Brazil.
Iná S
IS
Santos
Programa de Pós-Graduação em Epidemiologia, UFPel, Pelotas, Brazil.|Department of Preventive Medicine, School of Medicine, University of São Paulo, São Paulo, Brazil.
Alicia
A
Matijasevich
Programa de Pós-Graduação em Saúde da Criança e do Adolescente, UFRGS, Porto Alegre, Brazil.|Serviço de Genética Médica, HCPA, Porto Alegre, Brazil.|Departamento de Genética, UFRGS, Porto Alegre, Brazil.
Roberto
R
Giugliani
John A Scholl MD and Mary Louise Scholl MD Endowed Professor, Department of Pediatrics and Department of Epidemiology and Public Health, University of Maryland, Baltimore, Maryland.
Maureen
M
Black
D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D055028:Comparative Genomic Hybridization; D002658:Developmental Disabilities / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D005260:Female; D005817:Genetic Counseling; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D007361:Intelligence Tests; D008297:Male; D015995:Prevalence
birth defects; genetics causes of diseases; intellectual disability; mental retardation; population-based studies