rs121907970

A SNP in the HEXA gene on chromosome 15. Its most notable genotype is A;G: Carrier of a Tay-Sachs pseudodeficiency allele

Gene
HEXA
Location
Chr 1572,350,584 (GRCh38)
Highest magnitude
2.0Worth knowing
Tested on
23andMe, AncestryDNA
Minor allele frequency
<1%

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

  1. G;GGoodcommon in clinvarTypical · 0.0
  2. A;GMost notableNot ratedCarrier of a Tay-Sachs pseudodeficiency alleleWorth knowing · 2.0
  3. C;CGoodMiscall by Ancestry; actually represents the common/benign genotypeTypical · 0.0

SNPedia records rs121907970 on the minus strand: (C;C), (C;T), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Other HEXA SNPs

All HEXA SNPs

Notes

From SNPedia

Notes

aka c.739C>T (p.Arg247Trp or R247W) This variant is considered benign by the most recent submitter to ClinVar. It leads to a pseudodeficiency of beta-hexosaminidase A, which means that in the standard enzymatic tests for Tay Sachs that use a synthetic substrate, it will appear to have no HEX A activity (at least if coupled with a second 'disease-causing' allele). However, in the real world (i.e. in the individual and when acting on true substrates), the enzyme is reported to normally be fully functional.

A;G

see discussion on main rs-page

C;C

Error by Ancestry; this should be the (C;C) common/benign genotype.

Source and license

Adapted from rs121907970 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.