Introduction: Based on clinical and genetic knowledge about certain syndromes, in recent decades the concept of behavioural phenotypes has been developed in an attempt to deal with the complex relations between genes and behaviour. The model is not linear but rather each type of behaviour is determined by the interaction of different genes and modulated by environmental factors.
Development and conclusions: The aim of this review is to provide a global view concerning the concept of 'behavioural phenotypes' based on the description of the molecular mechanisms and clinical observations of some syndromes. There is clearly a need for geneticists, who work in a laboratory, and clinicians, who can offer qualitative and quantitative data about behaviour in certain genetic syndromes, to work in collaboration. For this reason this study describes the clinical instruments that make it possible to evaluate the core aspects of behaviour and hence undertake their scientific study in situations in which their genetic dysfunction is already known.