rs2143340

A SNP in the TTRAP gene on chromosome 6. Its most notable genotype is G;G: > 2x risk of dyslexia and poor reading performance

Gene
TTRAP
Location
Chr 624,658,843 (GRCh38)
Highest magnitude
2.3Worth knowing
Tested on
23andMe, AncestryDNA, FamilyTreeDNA
Minor allele frequency
15%

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

  1. G;GMost notableBad> 2x risk of dyslexia and poor reading performanceWorth knowing · 2.35% of people
  2. A;GBadincreased risk of dyslexia and poor reading performanceWorth knowing · 2.025% of people
  3. A;AGoodcommonTypical · 0.071% of people

SNPedia records rs2143340 on the minus strand: (C;C), (C;T), (T;T). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Frequency

Share of each genotype in 4 HapMap populations.

  • AverageG;G 5% A;G 25% A;A 71%
  • European ancestry (Utah)G;G 6% A;G 28% A;A 66%
  • Han Chinese (Beijing)G;G 4% A;G 18% A;A 78%
  • Japanese (Tokyo)G;G 4% A;G 22% A;A 73%
  • Yoruba (Nigeria)G;G 3% A;G 32% A;A 65%

Conditions, medicines and genes

Notes

From SNPedia

Show notes, about 140 words

genetic risk for poor reading performance. Rs2143340, a SNP in the TTRAP gene, is in a region that crops up in several independent studies as likely to associated with dyslexia. The risk allele in the US/UK Caucasian populations studied is (C), and it is indicative of a risk haplotype found in ~18% of the general population but up to ~28% of severely dyslexic individuals. It is not thought that rs2143340 is a functional SNP; instead, it marks the haplotype known as rs4504469-rs2038137-rs2143340 "1-1-2" since the other two SNPs are the common forms whereas the significant form for rs2143340 is the rare form. The functional effect of this haplotype appears to be on the KIAA0319 gene, in that KIAA0319 gene activity associated with the 1-1-2 risk haplotype is 40% lower than for other haplotypes, and other genes aren't noticeably affected.

Source and license

Adapted from rs2143340 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.

SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.