Over the past 30 years the study of behavioral phenotypes in genetic syndromes has changed dramatically. Initially, the research has dealt with specific problems such as self-injurious behavior in Lesch-Nyhan syndrome, hyperphagia in Prader-Willi syndrome or hyperacusis in Williams syndrome. The field of interest has expanded progressively to cover the route from genes to cognition and complex behavior. This development is associated with an increase in knowledge about the typing and gene expression, which today cannot be ignored by the regulatory sequences, epigenetic mechanisms, the changes in the number of copies, or the nucleotide variations in allelic abnormalities. The study of the relationship between genes and behavior could also benefit from increasingly accurate descriptions of the structures of the central nervous system and their activities through the refinement of the techniques of neuropsychological and neuro-electro physiopathological neuroimaging. It has had a prominent place among the social aspects dealing with complex behaviors for more than three decades. The exploration is guided by the fragile X and Williams syndrome, where the social dysfunctions are particularly pronounced, and where they continue to show encouraging results. Many problems are interconnected, instead, delaying the achievement of important milestones in other genetic syndromes. Among these the most important are represented by the failure of psychiatric studies of more standardized phenotyping in confirming the presence of symptoms of the autistic spectrum, uncertainty about role models for diagnostic categorization, the discussion on whether to base all significant social deficits on simultaneous (or comorbidities) of an autism spectrum disorder, and the frequent omission of measuring adaptive behaviors in the definition of behavioral phenotypes.
REFERENCES
Harris J. Advances in understanding behavioural phenotypes. American Journal of Medical Genetics. Part C, Seminars in Medical Genetics, 2010; 154C: 389-399.
Swillen A., de Ravel T., and Oliver C. Social phenotypes in genetic syndromes. Journal of Intellectual Disability Research, 2012; 56: 919-921.