rs121918344

A SNP in the CNGB3 gene on chromosome 8. Its most notable genotype is A;A: Complete achromatopsia (color-blindness)

Gene
CNGB3
Location
Chr 886,632,768 (GRCh38)
Highest magnitude
4.0Very important
Tested on
AncestryDNA

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

  1. G;GGoodcommon in clinvarTypical · 0.0
  2. A;GBadCarrier for colorblindness related conditionWorth knowing · 2.0
  3. A;AMost notableBadComplete achromatopsia (color-blindness)Very important · 4.0

SNPedia records rs121918344 on the minus strand: (C;C), (C;T), (T;T). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Other CNGB3 SNPs

All CNGB3 SNPs

Notes

From SNPedia

Notes

rs121918344, also known as S435F or SER322PHE, is a SNP in the cyclic nucleotide-gated channel beta-3 CNGB3 gene. Originally observed in Pingelapese islanders, a condition involving total colorblindness, photophobia, nystagmus, 20/200 visual acuity, yet a normal-appearing retina, was eventually found by sequence analysis to be due to a C-to-T transition causing a serine-to-phenylalanine substitution at amino acid 435 of this (CNGB3) gene.

Source and license

Adapted from rs121918344 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.