What is a SNP? rsID and genotype explained
Your raw data file consists of hundreds of thousands of marker rows. Here is what each row means — and what DNAHelper can read from it.
A SNP is a position, not a trait
DNA is a letter code of A, T, C and G. At certain positions people differ — the same position can hold an A in one person and a G in another. Such a position is called a SNP (single nucleotide polymorphism). The ~600,000–700,000 markers in your raw data file are positions where variation is common in the population — not a list of traits.
Your genotype is your two letters
You have two copies of every chromosome (one from each parent), so every SNP has two letters in you — for example AG or GG. That is your genotype at that position. In the raw data file a row looks roughly like this:
rs1801133 1 11856378 AG
The columns are: rsID, chromosome, position, genotype. That is all the file contains — no interpretation, just letters.
rsID is an ID number, not a result
rsID (e.g. rs1801133) is a reference number in the dbSNP database that identifies exactly which genetic variant it is. The same rsID means the same variant regardless of provider — the position coordinate can differ between reference versions, though (see Build 37 vs 38). It is what makes it possible to connect your genotype to published research studying that exact position.
What research links — association, not diagnosis
Studies can show that people with genotype GG at a certain rsID on average have a statistical link to a trait — for example a slightly higher value on some measure. That is an association, not a destiny: environment, lifestyle and thousands of other positions matter more together. DNAHelper therefore shows every link with its evidence strength — strong, well-replicated links are clearly marked against weaker findings. Read how we grade evidence in the methodology.
Why a SNP can be missing from your results
Every provider measures a different subset of SNPs. If your file does not contain an rsID a link is built on, DNAHelper cannot read it — we show the data as missing rather than guess. That is why results can differ between a MyHeritage file and a 23andMe file.
What DNAHelper does with the rows
Everything happens locally in your browser: the file is parsed, your genotypes are matched against the trait database and every result is shown with its evidence strength. The file is not uploaded — the only exception is the optional DNA Chat feature, where you consent to sharing selected variants. Read exactly what happens to your DNA file.
Also: Look up an rsID — free tool · What is imputation? · Why results differ · What is a raw DNA file? · English overview