Mental retardation (MR) is the most common developmental disability, affecting 2–3% of the general population. A major challenge in both clinical practice and research in the field of MR is to identify the underlying causes: genetic, chromosomal and environmental factors that have an influence on a person's development and behavior.

We present the results of our study regarding genetic abnormalities associated with mental retardation in children.

A total of 180 children were studied using a diagnostic protocol based on dysmorphologic and clinical assessment. A disease, familial and personal history were noted. All patients were evaluated by clinical and paraclinical exams (including dysmorphological features, psychological tests, neurological features, neuroimagistic studies). Genetic investigations included a karyotype with GTG banding, FISH and array-CGH.

A specific causes for the mental handicap was identified in 80 children (44%).

These included a chromosomal abnormality in 32 cases (17%), microdeletion syndromes in 25 children (14%), recognizable syndromes in 23 (13%). Array CGH identified a 22q11 deletion in a girl with unusual phenotype for DiGeorge syndrome, a Xp21 duplication in a girl with severe phenotype (including sever mental retardation, epilepsy, dysmorphic features, genital anomalies, glaucoma, dental anomalies), and a 4p14 deletion in a girl with moderate mental retardation, dysmorphic features, diparesis, congenital heard malformation.

While clinical diagnosis and conventional techniques form the mainstay of investigation of children with mental retardation, array CGH proved important diagnostic tool. Acknowledgments: National Research Program PN II, Project 42–130, CAPACITATI 29/2007–2009 Project; CNCSIS, Project 1203