Which genetic disorder can be diagnosed through karyotyping?

Karyotyping is a laboratory technique used to visualize an individual's complete set of chromosomes, allowing for the detection of chromosomal abnormalities such as aneuploidies, large deletions, and duplications. Down's syndrome, which is caused by the presence of an extra copy of chromosome 21 (trisomy 21), can be directly identified through karyotyping. The technique allows for the examination of the number and structure of chromosomes, making it a useful tool in identifying this particular genetic disorder.

In contrast, Alzheimer's disease, cystic fibrosis, and Huntington's disease are primarily the result of single-gene mutations. These conditions cannot be identified through karyotyping, as they involve small, specific genetic changes rather than large chromosomal abnormalities. Therefore, the ability of karyotyping to reveal chromosomal disorders, like the extra chromosome associated with Down's syndrome, illustrates its role in diagnosing this genetic condition effectively.