How many chromosomes do individuals with Turner syndrome have?

• A. 45 Chromosomes Instead of the Typical 46.
• B. 46 Chromosomes.
• C. 47 Chromosomes.
• D. 44 Chromosomes.

Answer: (A)

Turner syndrome is a condition of sex-chromosome monosomy, where one X chromosome is missing. Humans usually have 46 chromosomes, with either two X chromosomes in females or an X and a Y in males. When one sex chromosome is absent, the total becomes 45, so individuals with Turner syndrome have 45 chromosomes. In some cases, there can be mosaicism (some cells are 45,X and others 46,XX), but the classic count taught is 45. The other options don’t fit because 46 is the normal karyotype, 47 would mean an extra chromosome, and 44 would be an autosomal monosomy, which is not typical for Turner.