The concept of autism has led to the inclusion of increasingly heterogeneous and atypical individuals. Clinicians find it difficult to establish clear boundaries between autism, other psychiatric and/or neurodevelopmental disorders and atypical individuals, despite standardized instruments. What's more, these standardized instruments have been built around the male phenotype, and do not allow for an accurate assessment of autism in women. Whatever the gender, the diagnosis is based on multiple, variable, disabling and persistent deficits. Finally, we'll mention a few recommendations to help clinicians make a diagnosis or invoke the precautionary principle.