Childhood autism with its difficulties in relating to others has been for a long time imputed to conscious or unconscious educative errors of the mother. Clinical and biological data can be opposed to this conception. Familial movies analysis exhibits early disorders in attention, perception, intention, limitation and muscular tone. Later, recording of cerebral reactivity to auditory stimulations confirms deficiencies in attention, perception, association ... and shows a diminution of the responses in the left hemisphere. Abnormalities in the development of the cerebellum are also described. Modifications of main neurotransmitters as Dopamine and Serotonin and their derivatives are often present. A recent study of the genes which control enzymes regulating metabolism of these transmitters does not show evident modifications by polymorphism analysis. On the contrary a peculiarity in the Harvey-RAS gene allows to differentiate in a significant way an autistic and a normal group. This gene is involved in the regulation of growth factor and/or differentiation of neural cells. These observations support the hypothesis considering autism as a relating deficiency due to a developmental disorder of central nervous system.