Description: The karyotype is the set of chromosomes present in the nucleus of a eukaryotic cell, organized into homologous pairs and characterized by their number, shape, and size. In humans, the normal karyotype consists of 46 chromosomes, arranged in 23 pairs, of which 22 are autosomes and 1 pair is sex chromosomes. Visualization of the karyotype is performed through cytogenetic techniques, where images of the chromosomes are obtained during the metaphase of mitosis. This representation allows for the identification of chromosomal abnormalities, such as duplications, deletions, or translocations, which may be associated with various genetic diseases. The karyotype is fundamental for understanding inheritance and genetic variability and also plays a crucial role in developmental biology and evolution. Its study has enabled scientists to unravel the complexity of genetic material and its relationship with phenotypic characteristics, as well as with predisposition to certain pathologies. In summary, the karyotype is an essential tool in genetics and bioinformatics, providing valuable information about the structure and function of DNA in eukaryotic organisms.
History: The concept of karyotype was developed in the 20th century, with significant advances in cytogenetics. In 1956, American biologist Joe Hin Tjio and geneticist Albert Levan determined that the normal number of chromosomes in humans is 46, establishing a standard for chromosomal studies. Since then, karyotype analysis has been fundamental in identifying genetic disorders and in cancer research.
Uses: The karyotype is used in medicine to diagnose genetic diseases, such as Down syndrome, which is characterized by the presence of an extra chromosome 21. It is also employed in cancer research to identify chromosomal alterations that may contribute to malignancy. In evolutionary biology, the karyotype helps understand phylogenetic relationships among species.
Examples: An example of karyotype analysis is the study of fetal cells to detect chromosomal abnormalities through amniocentesis. Another case is the analysis of tumor cells to identify specific translocations, such as the BCR-ABL translocation in chronic myeloid leukemia.
