[Clinical approach to mental retardation of genetic origin]

Etiological investigations of mental deficiencies and their syndromic analysis have greatly progressed with advancing knowledge in the field of genetics and the advent of new technical procedures. Fast diagnostic tests are now available for certain syndromes, particularly those related to micordeletions. Clinical diagnosis remains however the necessary prerequisite for ordering such tests. The clinical examination not only provides a detailed description of the physical condition, but also provides essential information on behavioral and cognitive disorders. Distinctive behavioral patterns observed in some syndromes are suggestive of a "behavioral phenotype". This pattern can be a valuable clue to diagnosis and also allows for early intervention and counselling specifically aimed at dealing with predicted behavioral abnormalities.