tsütogenetika

Tsütogenetika, commonly called cytogenetics, is the branch of genetics that studies the structure, number, and function of chromosomes in cells. It combines cytology and molecular genetics to understand how chromosomal alterations relate to development, fertility, and disease. The field uses laboratory techniques to visualize and analyze chromosomes in metaphase spreads and interphase nuclei, and it is central to clinical genetics and cancer genetics.

Key techniques include karyotyping with G-banding to identify gross chromosomal abnormalities; improved banding and higher-resolution methods; fluorescence in situ hybridization (FISH) to detect specific DNA sequences on chromosomes; multicolor FISH (spectral karyotyping). More recently, array comparative genomic hybridization (array-CGH) and sequencing-based methods enable detection of smaller copy-number variations and structural rearrangements. In prenatal and cancer diagnostics, samples such as peripheral blood, bone marrow, amniotic fluid, or chorionic villus sampling are used.

Applications include prenatal diagnosis of aneuploidies and structural rearrangements (for example, trisomy 21 and monosomy X); identification of chromosomal abnormalities in infertility and miscarriage; cancer cytogenetics through characteristic translocations, deletions, and duplications (such as BCR-ABL in chronic myeloid leukemia); prognosis and treatment decisions. Limitations include the limited resolution of conventional karyotyping, the inability to detect certain balanced rearrangements by some methods, and reliance on dividing cells; integration with higher-resolution methods improves detection.

The field continues to evolve with genomic technologies enabling comprehensive chromosomal and subchromosomal analyses.