Which chromosomal abnormality is defined as having three complete sets of chromosomes?

Which chromosomal abnormality is defined as having three complete sets of chromosomes?

• A. Triploidy
• B. Trisomy 21
• C. Turner syndrome
• D. Klinefelter syndrome

Answer: (A)

Having three complete sets of chromosomes means triploidy. In humans, that’s 69 chromosomes (3 × 23) instead of the normal 46. This occurs when an extra haploid set is present, typically from fertilization errors, and triploidy is usually not compatible with sustained development, often ending in miscarriage. This differs from a trisomy, where only one chromosome is present in three copies (for example, three copies of chromosome 21 in Down syndrome). Turner syndrome involves the loss of an entire sex chromosome (45,X), and Klinefelter syndrome involves an extra X chromosome in a male (47,XXY).

Having three complete sets of chromosomes means triploidy. In humans, that’s 69 chromosomes (3 × 23) instead of the normal 46. This occurs when an extra haploid set is present, typically from fertilization errors, and triploidy is usually not compatible with sustained development, often ending in miscarriage. This differs from a trisomy, where only one chromosome is present in three copies (for example, three copies of chromosome 21 in Down syndrome). Turner syndrome involves the loss of an entire sex chromosome (45,X), and Klinefelter syndrome involves an extra X chromosome in a male (47,XXY).