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

(Micro)deletion/(Micro)duplication syndromes in one of the most common cause of intellectual disability in children, often in association with a sever phenotype. Introducing of new genetic techniques of molecular diagnosis, like array-CGH, allowed identification of new microdeletion/microduplication syndromes. This paper presents our experience regarding diagnosis and management of children with (micro)deletion/(micro)duplication syndromes.

250 children with mental retardation, selected using a diagnostic protocol based on personal and familial history, general and neurological examination, dysmorphologic and psychological assessment, specific paraclinical tests, were included in our study. in 130 children genetic investigations, including karyotype with GTG banding, FISH and array-CGH, were performed.

44 (micro)deletion/(micro)duplication syndromes were diagnosed: 16 cases with Williams syndrome, 10 cases with Angelman syndrome, 3 cases with Prader-Willi syndrome, 2 cases with Wolf-Hirschorn syndrome, 3 cases with cri-du-chat syndrome, and one from the following syndromes: DiGeorge, 1q deletion, 3p deletion, 3q duplication, 4p deletion, 8p deletion, 9p deletion, 12p duplication, Xp duplication, Xq duplication. the management of these children included physical therapy, speech therapy, behavioral therapy, the therapy of associated conditions (epilepsy, malformation etc.).

An early diagnosis of (micro)deletion/(micro)duplication syndromes is very important for a proper management of these conditions. New molecular genetics tests are useful for identification of some new or very rare anomalies.

Financial support: CNCSIS 1203 project, PNII 42130.