Definition:
Karyotyping is a laboratory technique that allows the visualization and analysis of an individual’s chromosomes. It involves arranging and examining the chromosomes from a cell sample to determine their number, size, shape, and structural abnormalities.
Process:
The process of karyotyping typically involves the following steps:
- Cell Culture: Cells are collected from an individual, typically through a blood sample, and cultured in a laboratory to promote cell growth.
- Cell Arrest: The cultured cells are treated with chemicals or other methods to stop them from dividing at a specific stage, usually metaphase, when chromosomes are most visible.
- Chromosome Preparation: The arrested cells undergo various treatments to remove proteins, stain the chromosomes, and spread them onto a slide for microscopic analysis.
- Microscopic Analysis: The prepared slide is examined under a microscope by a trained cytogeneticist who analyzes the chromosomes’ characteristics, such as banding patterns, size, and centromere position.
- Chromosome Identification: The cytogeneticist arranges the chromosomes into a karyogram, a standardized display of chromosomes, based on their size, banding pattern, and other identifying features.
- Karyotype Analysis: The cytogeneticist analyzes the karyotype to identify any chromosomal abnormalities, such as extra or missing chromosomes, translocations, deletions, or inversions.
Applications:
Karyotyping has several applications in medicine and genetics:
- Prenatal Diagnosis: Karyotyping can identify chromosomal abnormalities in unborn babies, helping diagnose conditions like Down syndrome, Turner syndrome, or Klinefelter syndrome.
- Cancer Diagnosis and Prognosis: Karyotyping helps identify chromosomal abnormalities commonly found in different types of cancer, aiding in diagnosis, selecting targeted therapies, and predicting disease outcomes.
- Genetic Disorders Investigation: Karyotyping is used to diagnose genetic disorders caused by chromosomal abnormalities, such as Prader-Willi syndrome, Angelman syndrome, or cri-du-chat syndrome.
- Forensic Analysis: Karyotyping can be used in criminal investigations, identifying suspects or victims by comparing their DNA profiles to collected samples.