rs7755898
A SNP in the CYP21A2 gene on chromosome 6. Its most notable genotype is T;T: Congenital adrenal hyperplasia
- Gene
- CYP21A2
- Location
- Chr 632,040,421 (GRCh38)
- Highest magnitude
- 5.0Very important
- Tested on
- Not on consumer chips
Genotypes
As shown in 23andMe and AncestryDNA files.
- C;CGoodcommon in clinvar
- C;TBadmiscalled by 23andMe, but should indicate being a carrier of allele for congenital adrenal hyperplasia
- T;TMost notableBadCongenital adrenal hyperplasia
On SNPedia: (C;C), (C;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 CYP21A2 SNPs
- rs6445T;TCongenital adrenal hyperplasiaVery important
- rs6471T;TCongenital adrenal hyperplasiaVery important
- rs6475A;ACongenital adrenal hyperplasiaVery important
- rs6476A;ACongenital adrenal hyperplasiaVery important
- rs151344503A;ACongenital adrenal hyperplasiaVery important
- rs151344505A;ACongenital adrenal hyperplasiaVery important
- rs201552310A;ACongenital adrenal hyperplasiaVery important
- rs267606757C;CCongenital adrenal hyperplasiaVery important
Notes
From SNPedia
Show notes, about 170 words
This SNP is supposed to serve as a marker for the Q318X null allele of the 21-hydroxylase gene. This would generally be associated, when homozygous, with the most severe form of congenital adrenal hyperplasia (salt wasting). However, a random survey of 10 publicly uploaded genomes showed all 10 to be carriers. This is well out of Hardy-Weinberg equilibrium, making the accuracy of this SNP as reported by 23andme suspect. Positive results should be clinically correlated and verified in cooperation with your health care provider.
C;T
This genotype should indicate being a carrier of Congenital adrenal hyperplasia, but most 23andMe users will find this in their data due to a problem with that testing platform being confused by a nearby pseudogene (source)
T;T
23andMe users are often mistakenly identified as heterozygotes at this position. However you are being identified as having 2 copies of the rare allele, causing Congenital adrenal hyperplasia. See discussion at Congenital adrenal hyperplasia
Source and license
Adapted from rs7755898 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.