Which statement best describes SNPs?

• A. SNPs are variations at a single nucleotide position, the most common polymorphism.
• B. SNPs are long repeated sequences.
• C. SNPs are protein coding genes.
• D. SNPs are RNA variants.

Answer: (A)

SNPs are variations at a single nucleotide position in the DNA sequence and represent the most common form of genetic polymorphism. This means that at a particular spot in the genome, most people have one nucleotide, while some individuals in the population have a different nucleotide, and this difference is present in a significant fraction of individuals (often with a minor allele frequency above 1%). Because SNPs occur so frequently across the genome, they serve as abundant genetic markers for studying inheritance and association with traits or diseases.

SNPs are variations in DNA, not long repeated sequences, not whole genes, and not RNA variants. While a SNP can influence gene function or regulation if it lies in a coding region or regulatory element, many SNPs are neutral and simply mark genetic variation. Their ubiquity and stability make them especially useful in genome-wide studies to map disease loci and understand genetic diversity.