Oncology Certified Nurse (OCN) Nursing Practice Test

Which genetic term describes a situation where there is a variation in DNA sequence that does not directly cause disease?

1. Missense

2. Aneuploidy

3. Polymorphisms

4. Translocation

The correct answer is: Polymorphisms

Polymorphisms refer to variations in DNA sequences that occur commonly within a population but do not necessarily lead to disease. These variations can manifest as differences in a single nucleotide (single nucleotide polymorphisms or SNPs) or in larger sections of DNA. Their presence can be related to normal genetic diversity, influencing traits such as physical appearance, response to medications, or susceptibility to certain diseases without directly causing them. In contrast, the other terms describe more specific genetic changes associated with disease or abnormal genetic structure. Missense mutations involve changes that result in a different amino acid being incorporated into a protein, which can affect protein function and potentially lead to disease. Aneuploidy signifies an abnormal number of chromosomes, which can be detrimental and associated with conditions like Down syndrome. Translocations involve the rearrangement of chromosome segments, often linked to certain cancers. Understanding these distinctions emphasizes why polymorphisms signify genetic diversity rather than pathogenicity.