The Human Phenotype Ontology provides terms to describe specific phenotypic abnormalities rather than disease diagnoses. Nevertheless, it is common for descriptions such as 'Autism' to be used to describe individuals affected with Mendelian forms of neurodevelopmental disease and many other conditions. If possible, we recommend annotation using specific terms in other branchs of the Atypical behavior subontology, but if this is not possible, then terms from this branch may be used.