Why Do My Alleles Look Different in Other Companies' Reports?

Seeing the same genetic variant written differently across platforms is normal—nothing is wrong with your data. The difference comes down to which strand of DNA is being displayed.

Understanding DNA Strands

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 Looks Different Across Platforms

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 your reports.

Example

• SelfDecode shows: AG
• Another source shows: TC

These represent 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 understand this, you'll be able to recognize your SNPs no matter how they're written and compare results across tools with confidence.

Have questions? If you'd like clarification on a specific SNP or report, reach out to us at support@selfdecode.com—we're happy to help.