Rational selection of Genetic tests in Clinical Practice Part 1 - Cytogenetics, FISH and Microarray

Abstract

Advances in the fields of molecular medicine and genetic engineering have found applications in clinical practice in the form of diagnosis, treatment and prevention of genetic disorders. Genetic disorders can be broadly classified into three categories: Chromosomal disorders, Single gene disorders and multifactorial disorders. During evaluation of a suspected genetic disorder, apart from hematological, biochemical and radiological investigations we have to use some specialized investigations. Cytogenetics refers to the description of chromosome structure and the identification of genomic aberrations that cause diseases..Fluorescence In Situ Hybridization (FISH) is a process whereby chromosomes or portions of chromosomes are vividly painted with fluorescent molecules that anneal to specific regions. Chromosomal microarray analysis (CMA) is a high resolution, whole-genome screening technique that can identify most of the chromosomal imbalances detected by conventional cytogenetic analysis, as well as smaller sub microscopic deletions and duplications that are referred to as copy-number variants (CNVs) that may miss in the conventional karyotyping.