Cytogenetic methods

Cytogenetics is a section of genetics that studies the visible carriers of genetic information: mitotic, meiotic and polytene chromosomes, interphase nuclei, to a lesser degree - the mitochondria and chloroplasts. Therefore, cytogenetic methods are, first of all, the methods of chromosomes studying – their number counting, structure and behavior during cell division description, and the relationship between the change in chromosome structure to the features variability.

Human chromosomes can be studied in peripheral blood lymphocytes, bone marrow cells, tumors and others. Abnormal chromosome set or structure indicates the presence of certain diseases, such as trisomy for the twenty-first chromosome is evidence of Down syndrome.

Cytogenetic methods are based on the cytologic analysis of genetic structures, comparing genetic phenomena with the structure and behavior of chromosomes and their parts (analysis of chromosomal and genomic mutations, building of chromosome cytological maps, cytochemical study of gene activity, and so on).

For chromosomes and other carriers of genetic information structure study light and electron microscopy are used.

Molecular cytogenetic method

The method of molecular fluorescence in situ hybridization (FISH) is based on the ability of chromosomal DNA to form stable hybrid molecules with known by nucleotide composition nucleic acids fragments (probes) directly on the preparations of fixed cells, chromosomes and interphase nuclei. Result of hybridization is detected due to fluorescent labels.

This method allows proceeding from the study of chromosomes morphology to the DNA sequences analysis.

The main scope of fluorescence in situ hybridization (FISH): clinical cytogenetics, prenatal and pre-implantation diagnostics, oncology, oncogenetics, hematology.