SNPs and Genetic Variants: What They Are and Why They Matter

Single nucleotide polymorphisms — SNPs (pronounced “snips”) — are the most common form of genetic variation in the human genome. A SNP represents a difference in a single nucleotide at a specific genomic position, where two or more alternatives exist across individuals in a population.

Clinical Significance

SNPs underpin much of what we understand about the genetic basis of common complex diseases. GWAS have identified thousands of SNP-disease associations including:

• Cardiovascular disease (APOE, PCSK9 variants)
• Type 2 diabetes (TCF7L2, KCNJ11 variants)
• Breast and colorectal cancer (BRCA1/2, APC variants)
• Drug metabolism (CYP2D6, CYP2C19, VKORC1 variants)

SNP Panels vs. Full Genome Sequencing

SNP arrays provide rapid, cost-effective screening for known variants but cannot detect novel or rare mutations. Full genome sequencing captures all variants — known and novel — providing a complete picture. Understanding SNPs allows practitioners to make more informed decisions about screening intervals, preventative interventions, and pharmaceutical choices.