[Smith-Magenis syndrome: a report of two new cases and an approximation to their characteristic behavioural phenotype]. / Síndrome de Smith-Magenis: aportación de dos nuevos casos y aproximación a su característico fenotipo conductual.

INTRODUCTION: Smith-Magenis syndrome (SMS) is a well defined contiguous gene syndrome that is caused by an interstitial deletion in the 17p11.2 region. It is characterised by the presentation of characteristic facial features, brachydactylia, short stature, varying degrees of mental retardation, occasional neuropathy and a specific behavioural phenotype that points to this entity. AIMS: Our aim was to report the cases of two children with SMS and carry out an approximation towards their characteristic behavioural phenotype. CASE REPORTS: We studied the cases of two 12-year-old children who were suspected of suffering from SMS following the findings of a physical exploration and the presence of a specific behavioural phenotype. This was confirmed by the genetic-molecular study which proved the existence of the 17p11.2 deletion. CONCLUSIONS: Although SMS is a relatively infrequent syndrome, a patient with mental retardation and characteristic dysmorphic features who presents an especially relevant behavioural disorder including different stereotypic movements, aggression phenomena and sleep disorders is suggestive of this diagnostic possibility.