[Etiology of mental deficiency. Study based on 3735 cases (author's transl)].

: A study on the etiology of MD was done on 3735 children with mental retardation. Selection of patients was verified by precise alphabetical train in order to obtain the different factors of MD with objectivity. The highest percentage of MD was constituted by pathology concerning pre- and/or peripartum problems (53.78%), being on the contrary very low the percentage of MD of unknown etiology (8.219%). Authors think that it is possible to verified correct diagnosis of cases with MD if the clinical knowledge is large the adequate para-clinical studies (biochemistry, EEG, EMG, cytogenetic and neuroradiology) are practised. The unknown etiology of MD must be low. In their opinion MD accompanying CNS malformations and dysmorphic syndromes must not be classified as MD of unknown etiology. Emphasis is done on the necessity of having in consideration real percentages of etiological factors when programs for education of subnormal children are developed.