X-linked mental retardation (XLMR) is a common, clinically complex and genetically heterogeneous disease arising from many mutations along the X chromosome. Although research during the past decade has identified >90 XLMR genes, many more remain uncharacterized. In XY males, duplication of any part of the X chromosome leads to functional disomy of the corresponding genes.

In this paper we present the case of a boy with a syndrome of Xq28 duplication. Methods: We present a 6 years old boy, admitted in the Department of Pediatric Psychiatry for evaluation. He presented sever mental retardation, autistic features, speech delay, hyperkinesia, and dysmorphic features (high forehead, partial palpebral ptosis, small nose, carp-shaped open mouth, micrognathia), recurrent infections. Cerebral MRI was normal. Genetic investigations, including katyotype with GTG banding and array-CGH, were performed.

Array-CGH indicated a dup(X)(q28) of less than 1.5 Mb. There were 15 duplicated genes, including MECP2 gene, which is involved in autism and mental retardation.

Duplications at Xq28 are often associated with autistic features/non-syndromic MR; alterations in MECP2 gene (duplicated in our patient) are described in Rett syndrome or as a specific phenotype. The alteration occurring at Xq28 band is responsible for the patient’s phenotype. Clinical manifestation of this child will be compared with those of other patients with the same duplication previously described to further delineate this syndrome.

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