Genetics of Mental Retardation
نویسندگان
چکیده
because of its prevalence (ca. 2%), the few therapeutic options that are currently available, and the resulting life-long harm to the affected persons, their families, and society as a whole (1). Persons with an intelligence quotient (IQ) below 70 are considered mentally retarded; milder forms of mental retardation, with IQ between 50 and 70 (overall prevalence ca. 1.5%), are more common than moderate and severe forms with IQ below 50 (prevalence 0.4%). Mental retardation is characterized by impaired cognitive, linguistic, and social abilities. It is sometimes already manifest in infancy (with muscular hypotonia, poor visual contact, and diminished motor activity) or early childhood, e.g., with abnormal play and delayed attainment of developmental milestones. Mental retardation can be caused by genetic or non-genetic factors: for example, infection or intoxication during pregnancy, complications of delivery, or postnatal infection or trauma (table 1). Genetic causes are present in more than 50% of severely mentally retarded
منابع مشابه
OCCURRENCE OF REPEATED FETAL DEATHS AND A SON WITH SEVERE PHYSICAL AND MENTAL RETARDATION AMONG PROGENIES OF AN IRANIAN CHEMICAL WARFARE VICTIM
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