Two hit model and de novo mutation

Even though there are arising evidence that autism may be caused by environmental factors, many still believe that there are strong genetic influence in autism (Deletions and duplication of 16p11.2 is single most common cause of autism in genetic analysis and duplication of 7q11.23 also correlates with the cause of autism). In my search for my phd project, I looked into what genetic mechanisms may contribute to this increasing incidents of Autism and I found Two-hit model and the influence of de novo mutation.

If there is a molecular-phenotypic pathway, single mutation in that pathway may cause a change in phenotype (e.g. intellectual disability, depression, etc). Then, a second mutation (that may be caused from spontaneous mutation, de novo) can push the phenotype to autism or more severe neurological disorder. Even though it's only a model at this point, I thought it was very convincing. It supports the fact that autism is oligogenic disorder and also it's a partially heritable disorder. Partially heritable because there are high concordance rates between siblings in a family or twins in regards to ASD. Also, two-hit model explains how autistic kid can be born from a perfectly behaviorally normal parents (excluding environmental factors)...

so what do I do with this information...? Find these recessive genes? Breed mice with multiple known autism contributing genes to see the rate of autistic progeny? I don't know....hahaha.... :(