rs121908937

A SNP in the LCT gene on chromosome 2. Its most notable genotype is G;G: Congenital lactase deficiency

Gene
LCT
Location
Chr 2135,829,593 (GRCh38)
Highest magnitude
5.0Very important
Tested on
AncestryDNA

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

  1. G;GMost notableBadCongenital lactase deficiencyVery important · 5.0
  2. C;GBadCarrier of a congenital lactase deficiency alleleWorth knowing · 2.5
  3. C;CGoodcommon in clinvarTypical · 0.0

SNPedia records rs121908937 on the minus strand: (C;C), (C;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Other LCT SNPs

All LCT SNPs

Notes

From SNPedia

Notes

G;G

This genotype is reported to lead to congenital lactase deficiency.

C;G

In the absence of other mutations in this gene (LCT), this genotype represents an unaffected carrier. In the presence of another LCT mutation, though, this genotype could be associated with congenital lactase deficiency.

Source and license

Adapted from rs121908937 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.