Why are alleles for this SNP different elsewhere?

Why Do My Alleles Look Different in Other Reports?

It can be confusing to see the same genetic variant written differently across platforms — but in most cases, nothing is wrong with your data. The difference comes down to how DNA is displayed.

A Simple Way to Think About It

Your DNA is shaped like a twisted ladder (a double helix). Each “rung” of that ladder is made of two matching bases, one on each strand:

• A pairs with T
• C pairs with G

At specific positions in your DNA — called SNPs (Single Nucleotide Polymorphisms) — the base you have can vary between people.

Why the Same SNP Can Look Different

Every SNP exists on two strands of DNA:

• The forward (positive / +) strand
• The reverse (negative / −) strand

Some companies and research databases report SNPs based on the negative (−) strand, while SelfDecode consistently reports all SNPs using the positive (+) strand. This keeps results standardized and easier to interpret across reports.

Because of this, the same genetic variant can appear different depending on which strand is being shown.

Example

• SelfDecode shows: AG
• Another source shows: TC

These are actually the same genetic information — just viewed from opposite strands of the DNA ladder.

What This Means for You

• Your DNA hasn’t changed
• One report isn’t more “correct” than the other
• The difference is purely a matter of strand orientation

Once you know this, you’ll be able to recognize your SNPs no matter how they’re written — and compare results across tools with confidence.

If you ever have questions about a specific SNP or report, feel free to reach out to our support team and we’ll be happy to help clarify.

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