Neurodevelopmental disorders are mainly represented by autism spectrum disorders (ASD) commonly known as autism, attention deficit hyperactivity disorder (ADHD), cerebral palsy, learning disabilities, developmental delays and intellectual retardation. A worrying situation is that neurodevelopmental disorders have become increasingly frequent over the past 30 years worldwide. In fact, the Autism Society of America has recently reported that autism is the fastest growing developmental disability, increasing annually at a rate of 10 to 17 percent. At least in part, this trend is explained by the increase of environmental pollution and inadequate nutritional balance at early stages of pregnancy, because the developing brain is extremely vulnerable to these factors. Moreover, if coexist genetically determined innate vulnerabilities these environmental agents could be act as extremely harmful factors even at doses much lower than those that affect people without special genetic vulnerabilities. In the present paper I describe a method that, due to a particular genetic predisposition, makes it possible to understand how external factors acting together with internal factors, might induce various gene-environment interactions with differential impact on the clinical outcome in ASD patients. This method is based on previously published papers and preliminary results of a study carried out in our center. Thus, the aim of the present paper is to insist in the need of including genetic characterization of vulnerabilities to environmental influences as part of the analysis protocol for all ASD patients. By applying this method we propose an approach that does not represent a DNA test to confirm a diagnosis, but a DNA-SNP analysis to detect especial vulnerabilities to several environmental factors in a multifactorial context. In this sense, I propose a method based on DNA polymorphism analysis as the first step to characterize vulnerabilities related to different ASD subtypes in order to design more individualized therapeutic and support strategies.