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.

Introducción y objetivo. El fenotipo conductual (FC) es un patrón característico de anormalidades motoras, cognitivas, lingüísticas y sociales, que se asocian de forma compatible con un trastorno biológico, sin desestimar la importancia de lo ambiental en su desarrollo. Teniendo en cuenta estos conceptos, hemos analizado diversas entidades con FC reconocidos, seleccionadas de acuerdo a su frecuencia de presentación, la compatibilidad de la asociación del FC con la enfermedad de base y la importancia del reconocimiento de la entidad para la adecuada orientación terapéutica y el correcto asesoramiento genético.

Desarrollo A modo organizativo, las hemos dividido en tres grupos de acuerdo con las características biológicas que se reconocen hasta el momento: a) FC asociados a enfermedades genéticas con base biológica identificada (síndromes de Lesch­Nyhan, Rett, X frágil, complejo esclerosis tuberosa, Noonan, Sotos, Aicardi, Angelman, Prader Willi, Williams, Down, Smith Magenis, Di George, Pallister Killian y Turner, entre otros; b) FC asociado a una enfermedad genética de base biológica aún no identificada (síndrome de Cornelia de Lange), y c) FC de base biológica aún no identificada asociado a etiologías diversas (autismo). En todas las entidades, analizamos los aspectos fenotípicos, clínicos, cognitivos, conductuales y biológicos, desde su modo de herencia hasta las bases moleculares.