Which method is used for visualizing the entire chromosome set to detect chromosomal abnormalities?

• A. Amniocentesis
• B. Karyotyping
• C. Chorionic villus sampling
• D. Preimplantation genetic diagnosis

Answer: (B)

Karyotyping is a method specifically designed for visualizing the entire set of chromosomes in an individual. This technique allows researchers and clinicians to observe the number, shape, and size of chromosomes, enabling the detection of chromosomal abnormalities such as aneuploidies (e.g., Down syndrome, which is caused by an extra copy of chromosome 21) or structural changes (such as deletions, duplications, or translocations).

During karyotyping, cells are typically collected during cell division, stained, and then photographed under a microscope to analyze the arrangement of chromosomes. This comprehensive visual representation is crucial for diagnosing genetic disorders and assessing chromosomal integrity.

Other methods mentioned, such as amniocentesis and chorionic villus sampling, are techniques used to collect samples for genetic testing but do not visualize chromosomes directly in the same way. Preimplantation genetic diagnosis, while related to genetic analysis at the embryo stage, focuses on specific genetic conditions rather than providing a complete chromosomal overview. Thus, karyotyping stands out as the method used to specifically visualize and assess the entire chromosome set for abnormalities.