Genetic Investigation of Some Behaviors and Impairments with Autism Spectrum Disorders Using Structural Equation Modeling

Autism is a severe developmental disorder of unknown etiology but with evidence for genetic influences. The current study combined 47 twins in order to improve statistical power. At least one proband in each pair was diagnosed as having autism spectrum disorder(ASD), using the DSM-IV category of pervasive developmental disorder. An investigation of genetic structure underlying autistic traits was performed. We use bivariate coefficient for this study. Among all possible values of the parameters, we found the maximum-likelihood estimate(MLE), the value that maximizes the log-likelihood for the model. A best fitting model of influences on autistic traits, incorporating additive genetic (A), shared environmental (C) and non-shared environmental influences (E), was generated using this model framework. We got the AE model as the best model by Akaike’s information criterion(AIC), then the estimated heritability was 0.74 for restricted and repetitive behaviors and interests(RRBI), whereas for social impairments(SI) it was 0.96. They are very high values of heritability, respectively.