Molecular karyotyping in the clinical setting

Microarray technology for the detection of putative pathological submicroscopic copy number variants (CNV) has become a standard tool in the field of molecular cytogenetics in recent years. In addition to the identification of somatic CNVs in tumour genetics this technology is increasingly used for the analysis of constitutional CNVs in patients with developmental delay. Array-based genomic hybridisation increases sensitivity in comparison to more conventional technologies such as comparative genomic hybridisation (CGH). Recent developments now allow a genome-wide detection of submicroscopic chromosomal alterations, deletions and duplications smaller than 100 Kb, thus significantly increasing the detection rate of chromosomal aberrations in patients suffering from idiopathic mental retardation. Several centers are already using array technology in their routine setting in the diagnostic approach to syndromes. Therefore, this overview focuses on the similarities, as well as the differences, of several basic array techniques.