Understanding Your SNPs: What Consumer Genomics Can and Can't Tell You
If you've taken a consumer DNA test from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA, the raw data file you can download is a long list of SNPs — single-nucleotide polymorphisms. A SNP (pronounced "snip") is a single position in your genome where the letter of your DNA code varies from person to person. Your file typically contains between 600,000 and 950,000 of these positions, each recorded as a reference ID (an rsID like rs429358), a chromosome, a position, and your two-letter genotype at that spot.
Most of those hundreds of thousands of positions have no published research attached to them at all — they're just places where humans happen to differ. Only a small fraction, roughly three to four percent, have been studied enough to carry a known scientific annotation in at least one public database. That annotated slice is what a genomics interpretation service like GeneticCoding.com actually explains: we cross-reference every annotated SNP in your file against public and government databases and translate the result into plain language.
The databases that make this possible are themselves public resources. ClinVar, maintained by the US National Center for Biotechnology Information, records clinical significance classifications for variants — whether a variant is considered pathogenic, likely pathogenic, of uncertain significance, likely benign, or benign. The GWAS Catalog, run by the European Bioinformatics Institute, curates genome-wide association studies linking variants to traits and disease risk. PharmGKB holds pharmacogenomic data on how variants affect drug response. dbSNP is the canonical reference for rsIDs, and MedlinePlus Genetics provides plain-language, publicly funded explanations of genes and conditions. Together these sources let a report cite the actual evidence behind each finding rather than inventing a score out of thin air.
A useful report separates findings into categories — health predispositions, carrier status, pharmacogenomics (drug response), ordinary traits, and lighter fun facts — and shows a transparent evidence-strength indicator for each one. Higher-stakes results, such as variants associated with adult-onset conditions, belong behind an explicit opt-in reveal with a recommendation to consult a genetic counselor, because a statistical association is never a diagnosis. Many people who carry a risk variant never develop the associated condition, and lifestyle, environment, and other genes all play a role your DNA file can't capture.
Finally, genetics is a moving target. New studies are published constantly, and a variant with no known meaning today may gain an annotation next year. That's why ongoing monitoring matters: re-checking the public databases for changes relevant to your previously analyzed SNPs, and alerting you when something genuinely new appears — without making you re-upload your file every time. Understanding what a SNP is, where the knowledge comes from, and what its limits are is the first step to reading your own genome with appropriate curiosity and appropriate caution.