QDPR mutations provoke hyperphenylalaninemia (Trujillano et al., 2014), (also called atypical phenylchetonuria (PKU), a genetic metabolic disease provoking postnatal cognitive deficit due to the neurotoxic effect of hyperphenylalaninemia; interestingly, PKU could be a comorbid condition of ASD, although with low prevalence (Baieli et al., 2003). This evidence concerns the gene QDPR and metabolic disease.