Now, consider the theoretical model of autism mentioned in this section above as a function of the oxytocin/oxytocin receptor system, in which the severity of the ensuing autism is assumed to be inversely proportional to the product of the normalized concentration of oxytocin O′ and the normalized abundance of the available oxytocin receptors (Ra′), i.e., S′ = 1/(Ra′O′). The gene discussed is OXT; the disease is autism.