rs234706

A SNP in the CBS gene on chromosome 21. Its most notable genotype is A;A: 0.50 reduced risk of cleft lip / palate, 0.51 reduced risk of non-Hodgkin lymphoma. Increased responsiveness to homocysteine-lowering effects of folic acid.

Gene
CBS
Location
Chr 2143,065,240 (GRCh38)
Highest magnitude
2.5Worth knowing
Tested on
23andMe, AncestryDNA, FamilyTreeDNA
Minor allele frequency
22%

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. A;AMost notableGood0.50 reduced risk of cleft lip / palate, 0.51 reduced risk of non-Hodgkin lymphoma. Increased responsiveness to homocysteine-lowering effects of folic acid.Worth knowing · 2.55% of people
  2. A;GGood0.94 reduced risk of cleft lip / palateMinor · 1.130% of people
  3. G;GGoodcommon in clinvarTypical · 0.065% of people

On SNPedia: (A;A), (A;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Frequency

Share of each genotype in 11 HapMap populations.

  • AverageA;A 5% A;G 30% G;G 65%
  • European ancestry (Utah)A;A 10% A;G 48% G;G 43%
  • Han Chinese (Beijing)A;A 0% A;G 4% G;G 96%
  • Japanese (Tokyo)A;A 0% A;G 6% G;G 94%
  • Yoruba (Nigeria)A;A 7% A;G 33% G;G 61%
  • African ancestry (Southwest US)A;A 11% A;G 39% G;G 51%
  • Chinese (Denver)A;A 0% A;G 5% G;G 95%
  • Gujarati IndianA;A 11% A;G 43% G;G 47%
  • Luhya (Kenya)A;A 4% A;G 44% G;G 53%
  • Mexican ancestry (Los Angeles)A;A 2% A;G 26% G;G 72%
  • Maasai (Kenya)A;A 3% A;G 39% G;G 58%
  • TuscanA;A 9% A;G 43% G;G 48%

Conditions, medicines and genes

Other CBS SNPs

All CBS SNPs

Notes

From SNPedia

Show notes, about 240 words

rs234706, also known as c.699C>T and C699T, represents a common variant in the CBS gene on chromosome 21. The most common allele for this SNP is rs234706(G) as named in dbSNP orientation, or (C) if in cDNA orientation; the only somewhat less common allele, found in one or two copies in 40 - 50% of the individuals in most populations, is rs234706(A), also known as 699T. There is significant uncertainty, and even to some extent controversy, over the consequences of the the 699T allele. Some individuals believe it leads to upregulation of the CBS gene, and (eventually) an overproduction of ammonia and/or a decrease in glutathione. Most peer-reviewed publications feel that there is little to no evidence for any negative effect of the 699T variant.web.mit.edu Being investigated in Ehlers-Danlos syndrome

A;A

We found a reduced risk of CL/P with mothers who carried the CBS C699T variant (rs234706); relative risk was 0.94 with one copy of the T allele (95% CI 0.63-1.4) and 0.50 (95% CI 0.26-0.96) with two copies (P = 0.008). PMID 18203168 A significantly reduced risk of NHL was associated with the homozygous TT genotype in CBS (rs234706, Ex9+33C>T) (OR = 0.51, 95 % CI 0.31-0.84) PMID 23913011

A;G

We found a reduced risk of CL/P with mothers who carried the CBS C699T variant (rs234706); relative risk was 0.94 with one copy of the T allele (95% CI 0.63-1.4) and 0.50 (95% CI 0.26-0.96) with two copies (P = 0.008). PMID 18203168

References

Source and license

Adapted from rs234706 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.