cytogénétiques

Cytogénétiques is a field of genetics that studies the structure and behavior of chromosomes. Chromosomes are thread-like structures found in the nucleus of eukaryotic cells that carry genetic information in the form of DNA. Cytogeneticists examine chromosomes to identify abnormalities in their number or structure, which can be associated with various genetic disorders and diseases, including cancer.

The primary technique used in cytogenetics is karyotyping. This involves culturing cells, typically from blood or bone marrow, arresting them in metaphase of cell division when chromosomes are most condensed and visible, and then staining and photographing them. The chromosomes are then arranged in order of size and banding pattern, creating a karyotype. This visual representation allows for the detection of aneuploidies (abnormal chromosome numbers) and structural rearrangements such as translocations, deletions, duplications, and inversions.

Beyond karyotyping, other cytogenetic techniques include fluorescence in situ hybridization (FISH), which uses fluorescent probes to detect specific DNA sequences on chromosomes, and comparative genomic hybridization (CGH), used to detect chromosomal gains and losses across the entire genome. These advanced methods provide higher resolution and specificity in identifying chromosomal alterations.

Cytogenetics plays a crucial role in clinical diagnostics, prenatal screening, cancer research, and understanding the genetic basis of developmental disorders. It helps in diagnosing genetic conditions, assessing the prognosis of certain diseases, and guiding treatment decisions.