BIOLOGICAL BASIS OF INFANTILE-AUTISM - I - GENETIC, NEUROIMMUNOLOGICAL AND NEUROCHEMICAL ASPECTS

In the first part of this review paper on biological basis of infantil e autism we describe the main genetic, neuroimmunological and neuroche mical investigations carried out in this pathology. Twin and segregati on analysis studies indicate that genetic factors may play a relevant role in the etiology of autism. However, although genetic factors are clearly involved, environmental variables must be also important. In f act, concordance rates for autism in monozigotic twins are not of 100% . Investigations related to autoimmunity hipothesis can be grouped int o three broad categories. The first includes studies on the cellular e lements of the immune system (T-cells and NK cells). The second group concerns studies on the humoral elements of the immune system. The thi rd category focuses on maternal-fetal tolerance and immunoreactivity s tudies. Likewise, in this context a viral hipothesis has been proposed to explain some cases of infantile autism. Thus, autism has been etio logically linked to numerous prenatal infections, including rubella, c ytomegalovirus, varicella zoster, herpes simplex and toxoplasmosis. On the other hand, although results are still inconclusive, a serotonerg ic dysfunction has been described in numerous patients with autism. Fu rthermore, a functional imbalance between monoamines has been suggeste d in this pathology. Endogenous opioids peptides have been also involv ed in the pathogenesis of autism. According with this hipothesis, the hyperfunction of the endogenous opioid system could explain the majori ty of the symptoms associated with autism.