الفهرس 
Mental Retardation
Etiology of mental retardation (intellectual disability):Only 14 pages are availabe for public view
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Abstract
Mental retardation (MR), was defined by the World Health Organization (WHO) (2007) as an intelligence quotient (IQ) ˂ 70),coupled with limitations in adaptive skills in two or more of the following areas: social skills, community living, communication, home living, health, self-direction,
work, and leisure. Mental retardation affects about 2-3% of the general population all over the world. 75-90% of the affected people have mild mental retardation, idiopathic mental retardation cases account for 30-50% of cases, according to, of which 25% are of unknown etiology presumed genetic and 25% are of unknown etiology presumed environmental. Conventional karyotyping is one of the cytogenetic methods which are used for diagnosis of possible chromosomal abnormality as a cause of intellectual disability. The aim of the present study was to screen the patients with unexplained mental retardation for possible visible chromosomal abnormalities to provide genetic counseling for the family members, explaining the recurrence risk along with management of mental retardation. The present work was carried out on 30 patients aged from 3 to 18 years suffering from mental retardation, attending Genetics’ Clinic Of Pediatric Department, Tanta University Hospital, whose family seeking for the diagnosis of the cause and possible management of mental retardation, all had IQ less than 70 with exclusion of cases with mental retardation due to known genetic
etiology including well defined syndromes due to single gene defect or
chromosomal aberrations such as known numerical chromosomal disorders and microdeletion syndromes, cases with mental retardation due to inborn error of metabolism, patients with abnormal thyroid function and Perinatal
asphyxia as a sole cause of mental retardation. Thirty healthy children, of matched age and sex, who are with normal IQ (90- 110), were enrolled in this study as a control group.