Introduction: Array comparative genomic hybridization (aCGH) is a high throughput and high resolution technique for the detection of chromosomal copy number variations (CNVs) in the form of deletions, amplifications and gains. Mental retardation is a genetically heterogeneous disorder and more than 90 genes for this disorder have been found on the X chromosome alone. CNVs of X-chromosome (X-CNVs) may be a significant cause of mental retardation in male patients.  In this study, the application of this technology has enabled the detection of X-CNVs in males with mental retardation.

Methods: aCGH was performed on patients presented with non-syndromic mental retardation from Pantai Hospital Kuala Lumpur, Malaysia using the Oxford Gene Technology (OGT) microarray platform to identify CNVs and their location on the chromosome.

Results: Three patients have been identified to have CNVs at a specific region in chromosome X (Xq21.1). Of the three patients, two show a variant duplication resulting in an extra genetic material, while one has a deletion.

Discussion: The region of X-CNVs detected encompasses the MAGT1 (Magnesium transporter protein 1) gene. MAGT1 is involved in N-glycosylation through its association with N-oligosaccharyl transferase and in Mg2+ transport in epithelial cells. Based on a study conducted by Molinari et al. (2008), a mutation in the MAGT1 gene was identified in an Australian family where 4 out of 5 children suffered from mild to severe X-linked mental retardation.

Conclusion: This shows that aCGH technology can help in the identification of the clinically relevant X-CNVs in males with mental retardation syndromes.