Cytogenetic

Cytogenetics is the branch of genetics that studies the structure and function of the cell, with a focus on chromosomes. Cytogenetic analysis examines chromosome number, morphology, and behavior during cell division to identify genetic abnormalities. This field integrates cytology and genetics to understand how chromosomal changes affect development, reproduction, and disease.

Techniques include classical karyotyping, where chromosomes are prepared from dividing cells and ordered by size and banding pattern; banding methods such as GTG-banding to reveal characteristic patterns; and more advanced molecular cytogenetic tools such as fluorescence in situ hybridization (FISH), multicolor FISH (M-FISH) or spectral karyotyping (SKY), and array-based platforms like array comparative genomic hybridization (array CGH) and next-generation sequencing–based approaches. These methods enable detection of numerical chromosomal abnormalities (aneuploidies), structural rearrangements (translocations, inversions, deletions, duplications), and submicroscopic changes.

Applications include clinical diagnosis of congenital anomalies and developmental delay, prenatal screening for chromosomal disorders via amniocentesis or chorionic villus sampling, and cancer cytogenetics where chromosomal changes drive tumor classification and prognosis (for example, translocations in leukemias). Cytogenetics also informs infertility workups and helps study mosaicism.

Samples are typically lymphocytes from blood, bone marrow, amniotic fluid, chorionic villi, or tumor tissue. The field continues to evolve with molecular cytogenetics, offering higher resolution and integration with genomic data, while complementing molecular genetics in research and diagnostics.