rs121908789
A SNP in the CFTR gene on chromosome 7. Its most notable genotype is -;T: carrier of a cystic fibrosis allele
- Gene
- CFTR
- Location
- Chr 7117,642,493 (GRCh38)
- Highest magnitude
- 3.0Important
- Tested on
- Not on consumer chips
Genotypes
As shown in 23andMe and AncestryDNA files.
- -;-Goodcommon in clinvar
- -;TMost notableBadcarrier of a cystic fibrosis allele
- T;TGoodcommon in clinvar
On SNPedia: (-;-), (-;T), (T;T). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.
Related
Conditions, medicines and genes
Other CFTR SNPs
- i4000292D;Dcystic fibrosisVery important
- rs74551128A;ACystic fibrosisVery important
- rs113993960-;-Cystic Fibrosis; homozygote for delta F-508 mutationVery important
- rs199826652-;-Cystic Fibrosis; homozygote for delta F-508 mutationVery important
- i4000309A;ACystic FibrosisVery important
- i4000294A;ACystic FibrosisVery important
- i4000296T;TCystic FibrosisVery important
- i4000297A;ACystic FibrosisVery important
Notes
From SNPedia
Show notes, about 120 words
rs121908789 is reported as a pathogenic SNP for cystic fibrosis in several sources, however, there is ambiguity in how it is reported so be sure to double-check any results regarding this SNP. This SNP is also known as c.3773dupT, p.Leu1258PhefsTer7, and perhaps most commonly, 3905insT. In genome build GRCh37, the position for this SNP on chromosome 7 is 117282547:117282548 (where the additional insertion of a T takes place). 23andMe uses it's own code names for this SNP, namely i4000324 and i5012017. For these two SNPs, the common/normal allele is 'D', and therefore the common/normal genotype is DD.
-;T
Cystic fibrosis mutation carrier; unaffected unless CF mutation present on other copy of CF gene
Source and license
Adapted from rs121908789 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.