Introduction and aims: A behavioural phenotype (BP) is a characteristic pattern of motor, cognitive, linguistic and social abnormalities that are associated in a way that is compatible with a biological disorder, while environmental factors are also known to be important in their development. Taking these concepts into account, we have analyzed several entities with acknowledged BP, which were selected according to the frequency of presentation, the compatibility of the association between BP and the underlying disease, and the importance of recognizing the entity, so as to enable suitable therapeutic guidance and proper genetic counselling.
Development: They were organized by dividing them into three groups according to the biological characteristics recognized to date: a) BP associated to genetic diseases with an identified biological basis (syndromes such as Lesch Nyhan, Rett, fragile X, tuberous sclerosis complex, Noonan, Sotos, Aicardi, Angelman, Prader Willi, Williams, Down, Smith Magenis, Di George, Pallister Killian and Turner, among others; b) BP associated to a genetic disease with an unidentified biological basis (Cornelia de Lange syndrome); and, c) BP with an as yet unidentified biological basis associated to diverse causations (autism). In all the entities phenotypic, clinical, cognitive, behavioural and biological aspects were analyzed from the way they are inherited to the molecular bases.