rs334
A SNP in the HBB gene on chromosome 11. Its most notable genotype is A;A: sickle cell anemia
- Gene
- HBB
- Location
- Chr 115,227,002 (GRCh38)
- Highest magnitude
- 5.0Very important
- Tested on
- AncestryDNA
- Minor allele frequency
- 2%
Genotypes
Plus strand, as in 23andMe and AncestryDNA files.
- T;TGoodnormal allele
- A;TBadcarrier of, but unaffected by, sickle cell anemia; greater malaria resistance
- AG;AGGoodcommon in clinvar
- A;AMost notableBadsickle cell anemia
SNPedia records rs334 on the minus strand: (A;A), (A;T), (AG;AG), (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.
- AverageT;T 94% A;T 6% AG;AG 0% A;A 0%
- European ancestry (Utah)T;T 100% A;T 0% AG;AG 0% A;A 0%
- Han Chinese (Beijing)T;T 100% A;T 0% AG;AG 0% A;A 0%
- Japanese (Tokyo)T;T 100% A;T 0% AG;AG 0% A;A 0%
- Yoruba (Nigeria)T;T 77% A;T 23% AG;AG 0% A;A 0%
Related
Conditions, medicines and genes
Other HBB SNPs
- rs11549407A;ABeta Thalassemia major; Hemoglobin beta-zeroVery important
- rs33945777T;TBeta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
- rs33960103G;GBeta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
- rs33971440T;TBeta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
- rs33974936T;TBeta Thalassemia major; Hemoglobin beta-zeroVery important
- rs33986703A;ABeta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
- rs34716011T;TBeta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
- rs34889882-;-Beta Thalassemia major; Hemoglobin beta-zero; possibly transfusion dependentVery important
Genosets
Genosets combine several genotypes. Twofold checks them in your report.
Notes
From SNPedia
Show notes, about 180 words
This position causes sickle cell anemia; one report concludes that everyone with this mutation descended from the same ancestor 7,300 years ago. It is an ambiguous flip and is very prone to confusion dbSNP uses the minus orientation *rs334(A) encodes the normal Hb A form of (adult) hemoglobin. *rs334(T) encodes the sickling form of hemoglobin, Hb S. 23andMe tests this snp under the name i3003137 on the plus orientation *i3003137(T) encodes the normal Hb A form of (adult) hemoglobin. *i3003137(A) encodes the sickling form of hemoglobin, Hb S. Note that the 1000 genomes project is also reporting this in the plus orientation. gs228 and gs229 cover these arguably better Only individuals homozygous for this allele, in other words having the rs334(T;T) genotype, will have sickle cell anemia. The (T) allele appears to have maintained through evolution due to the ~10 fold higher resistance to life-threatening forms of malaria that heterozygotes (rs334(A;T) genotypes) exhibit. See the SNPedia sickle cell anemia entry for more information.
A;A
sickle cell anemia
Source and license
Adapted from rs334 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.