IDENTIFICATION OF STRUCTURAL CHROMOSOMAL REARRANGEMENTS IN CHILDREN WITH IDIOPATHIC MENTAL RETARDATION USING HIGH RESOLUTION CHROMOSOME ANALYSIS

Introduction. Diagnosis of genomic and chromosomal anomalies is based on the application of cytogenetic and molecular technologies. The aim of the study. The objective of the work was the delivery and the use of the algorythm for diagnosis of structural genomic and chromosomal anomalies based on high-resolution chromosome analysis and molecular cytogenetics methods in children with idiopathic mental retardation Methods.High-resolution chromosome banding, molecular cytogenetic methods including fluorescence in situ hybridization (FISH) and molecular karyotyping (array CGH) were used. Results.Here we describe the results of cytogenetic and molecular cytogenetic studies of chromosomal/genomic microaberrations in 55 children with idiopathic mental retardation, developmental delay and small dysmorphic features. In all of these cases classical cytogenetic studies did not reveal gross microscopically detectable chromosomal aberrations. In order to detect or exclude unbalanced structural aberrations in these children we used a special algorythm of chromosome analysis based on the combined application of high resolution G-banding, in situ hybridization (FISH-method) and DNA microarrays (array CGH). Different types of chromosomal microaberrations in all of 55 children with mental retardation were identified. Conclusion. Step by step application of high-resolution banding and modern molecular cytogenetic and genomic technologies allowed to reveal microaberrations of genome (chromosome) and discover new etiological causes of idiopathic mental retardation and congenital malformation.