Mental retardation is defined as significantly lower than the average level of intellectual functioning in association with impairments in adapting, binding to changes in the central nervous system. Alternatively, such terms as mental stunting, reduced intellectual performance, mental retardation and intellectual disability, and more recently learning disorders, are used. In the 1990s there have been tremendous changes in terms of mental retardation by deviating from the traditional medical and biological concepts, according to which the impairment was treated as a state of irreversible and defining a low ceiling development. Mental retardation is not only biological disorder, but also the psychological state which occurs as a result of improper development process. The impact on this state are: the prenatal period (exposure to X-ray beam, the use of drugs by the mother during pregnancy, alcohol, cigarette smoke, drugs, viral and bacterial infections, immune factors), the perinatal period (shock to the newborn child, the brain damage, premature birth, asphyxia, iatrogenic mistakes) and postnatal period [a history of infectious diseases and complications of (measles and whooping cough), trauma (accidents), poisoning (e.g. lead) and food poisoning]. Classification of intellectual disability can be very different depending on the selected criteria. The most famous is a four stage classification of degrees: 1) light, 2) moderate, 3) a large and 4) deep retardation. As shown, genetic factors play a very important role in the causes of mental disability. Among the genetic factors that cause impairment are distinguished: changes in the number or structure of chromosomes, single-gene mutation, polygene and epigenetic heredity. More and more researchers focus on in-depth assessment of the role of genetic factors for these disorders. Not all of the factors has been discovered and thoroughly investigated, so further research is necessary. It is also clear that mental retardation, autism and epilepsy have a lot in common. Presented by us work presents some of the disease and their genetic causes.

mental retardation, genetic factors, neurology, tuberous sclerosis, Rett syndrome, Angelman syndrome, Prader-Willi syndrome, Smith-Lemli-Opitz syndrome, mental retardation associated with fragile X chromosome, Duchenne muscular dystrophy