Genetics causes of Intellectual Disability

What is it about?

The aims of this study were to estimate the prevalence and etiology of intellectual disability at 7-8 years of age in a birth cohort through clinical and laboratory investigation and associated factors. Participants were part of a cohort followed from birth and were included in this study due to suspected developmental delay according to the Battelle Screening Test, IQ below 70 according to WPPSI scale and / or behavior problems observed during the interview in previous follow-ups. Of the 4231 children in the 2004 Pelotas birth cohort, 214 were selected for genetic evaluation which included anamnesis, physical and dysmorphological examination and collection of blood and urine when indicated. A dataset including variables from this evaluation and the previous cohort of follow-ups such as variables of pregnancy and birth, social demographic and health-related and stimulation of the childTo be considered as having intellectual disability the child that presenting an IQ below 70 and problems in adaptive behavior. One hundred and seventy children from two hundred fourteen selected at baseline were diagnosed with intellectual disability and they were classified into five etiologic groups. Most children (44.4 %) were classified as having intellectual disability due to no biological causes, i.e., linked to environmental factors. The second largest group (16.6%) was the group of children with genetic intellectual disability which included children with Down syndrome, microdeletions and autosomal dominant and multifactorial diseases. Children with neonatal sequelae accounted for 13.3% and intellectual disability associated with other diseases such as epilepsy and ADHD also accountedfor 13.3%. The smallest group was idiopathic composed of children who even after clinical and laboratory investigation remained without a definite diagnosis. The prevalence of intellectual disability was 4.5 % and the prevalence of genetic intellectual disability 0.66 %.

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Why is it important?

This is one of the few birth cohorts from a middle income country which studied intellectual disability in an epidemiological and clinical approach.