Rs121918344

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.