rs28940871

A SNP in the HEXA gene on chromosome 15. Its most notable genotype is C;C: 23andMe = Tay-Sachs disease likely, but on other platforms this may be the normal form

Gene: HEXA
Location: Chr 1572,346,305 (GRCh38)
Highest magnitude: 5.0Very important
Tested on: 23andMe, AncestryDNA

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

SNPedia records rs28940871 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.

Conditions, medicines and genes

Tay-sachs diseaseCondition

Other HEXA SNPs

All HEXA SNPs

Notes

From SNPedia

Show notes, about 210 words

This position appears to have been flipped between b36 and b37. Extra scrutiny is warranted. rs28940871, also known as Leu451Val, L451V, or C1351G, is a mutation in the HEXA gene. Some variations of this gene are associated with Tay-Sachs disease. In a population of Iraqi Jews, this SNP was found in 21 of 62 Tay-Sachs disease carriers (33.9%) and in 0 of 100 noncarriers. The authors estimated that this SNP originated sometime between 1519 BC and 635 AD, with 442 BC as the best estimate (+/- 1,000 years). The Iraqi Jewish community started around 586 BC when the Babylonian king Nebuchadnezzar deported 10,000 to 40,000 of the Jews from the kingdom of Judea to Babylon. This was probably the time of separation of the Iraqi Jews from the rest of the Jewish people. OMIM 23andMe reports the risk allele as C, because it is on the minus strand.

G;G

For 23andMe users, this is the normal genotype. However see also Rs28940871(G;G)

C;G

Unaffected in absence of a second HEXA gene mutation; see discussion at Tay-Sachs disease.

C;C

This position is an ambiguous flip which seems to have been flipped between b36 and b37. 23andMe users who see GG at the 23andMe site, are normal. However using more recent dbSNP based data, (G;G) is the risk genotype. Tay-Sachs disease likely; see details

Source and license

Adapted from rs28940871 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.