' ' The etiology remains obscure: they have been suggested causes and biochemists, cerebral injury or some inherent riot psicognicas that result in perspective difficulties of learning, but does not have conclusive evidences in this sentido' ' (DALLY; HARRINGTON, 1978). The autismo still presents, unknown cause. Although, research tries to unmask genetic factors associates to the illness, providing discovered how much to the neurobiolgicas causes, these, linked to the autismo. As convulsions; mental deficiency; reduction of neurons and sinapses in amgdala, hipocampo and cerebellum; encfalo increased and serotonina circulating intent, all suggest fort genetic influence. At the same time, studies with monozygotic twin (MZ) demonstrate to agreement for the autismo in 36 92%, on the other hand with dizigticos twin (DZ), this agreement null or is diminished. However, to if considering cognitivas and social abnormalitys, the acceptance level goes up for 92% between MZ and 10% between DZ (CARVALHEIRA; VERGANI; BRUNONI, 2004). In way to emphasize the cited one above, other authors affirm that the hereditary succession also is a predisponent factor to the autismo, in which evidence recurrences of the upheaval in affected families, being able to be noticed a bigger index in relation to the general population (SOUZA; GUIMARES; BALLONE, 2004).
In order to strengthen the paragraph Gillberg (2006 above apud ALBUQUERQUE; CROSS; RUTHES, 2009, p.2) assevera that: ' ' The incidence of the upheaval is of 2 the 4 men for each woman, being affected 0.2% of the world-wide population. The risk of brothers of autistas to present the upheaval is of 4 5% and this incidence increases in identical twin for 60 90%' '. The infantile autismo is one of the main divisions of the autismo, that involves genetic factors, neurobiolgicos and ambient, even so has necessity, of bigger clarifications how much to these .causing factors. It has neurobiolgicos studies that they denote high levels of serotonina and dopamina, fenilcetonria, epilepsy, increase of ventricle, among others cerebral abnormalitys.