It is very difficult to evaluate the regions of chromosomes smaller than a certain size with karyotype analysis. Changes below 5-10 megabases (1 million bases) cannot be detected by conventional cytogenetic methods (Figure 1). Therefore, in cases that require analysis above a certain resolution (for example, in the diagnosis of microdeletions), FISH (fluorescent in situ hybridization) or array CGH (comparative genomic hybridization) methods are preferred. Array CGH is currently preferred for diagnostic purposes because it is a DNA-based method that can examine all chromosomal regions simultaneously.

The technique is similar to FISH. The basis of the method is based on comparing (hybridization) the reference DNA and the DNA to be examined with the help of fluorescently labeled primers. It belongs to the group of molecular cytogenetic methods. It is checked whether there is a deletion (break) or duplication (increase) in any region of the chromosomes. Different clinical findings occur depending on the content and functions of the affected genes in the problem area.

Advantages:

• Accurate detection of losses or gains in chromosomes, reliability and efficiency are high.
• Multiple genomes (DNA) can be compared at the same time.
• The study is performed by direct DNA extraction without the need for cell culture.
• With today’s technology, resolution has increased even more and even single base changes in the genome (DNA) can be detected.

Limitations:

• It is not diagnostic for polyploidies and balanced chromosomal carriers.
• There is a need for experts in the field and a bioinformatics team.

DNA Laboratories Genetic Diseases Evaluation Center Molecular Cytogenetics Laboratory; They are managed by Genetic Experts and work in close cooperation with the Molecular Cytogenetics Laboratory manager and laboratory personnel who have a minimum bachelor’s degree.

DNA Laboratories Molecular Cytogenetics Laboratory covers the application of molecular cytogenetic techniques, including the structural and functional organization of the chromosome and nucleus, genome variation, expression and evolution, chromosome abnormalities, and medical genetics and genomic variations.

Molecular Cytogenetics describes a multitude of techniques that work primarily with the entire genome or with specific targeted DNA. Some fields are as follows;

• Structural and functional organization of chromosome and nucleus
• Genome variation, expression and evolution
• Chromosome abnormalities and genomic variations in clinical genetics
• Applications in preimplantation, pre- and postnatal diagnosis
• Cancer and hematology research

DNA Laboratories uses the latest technologies in molecular cytogenetic techniques in fluorescence in-situ hybridization (FISH) analysis for a wide range of clinical settings, from prenatal and postnatal diagnosis to cancer.