rs121908548
A SNP in the SCN4A gene on chromosome 17. Its most notable genotype is C;T: Potassium aggravated myotonia; paramyotonia congenita
- Gene
- SCN4A
- Location
- Chr 1763,941,517 (GRCh38)
- Highest magnitude
- 4.4Very important
- Tested on
- AncestryDNA
Genotypes
Plus strand, as in 23andMe and AncestryDNA files.
- C;TMost notableBadPotassium aggravated myotonia; paramyotonia congenita
- C;CGoodcommon in clinvar
SNPedia records rs121908548 on the minus strand: (A;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.
Related
Conditions, medicines and genes
Other SCN4A SNPs
- rs80338784C;Tpossibility of Hypokalemic periodic paralysisImportant
- rs80338785G;Tpossibility of Hypokalemic periodic paralysisImportant
- rs80338788C;Tpossibility of Hypokalemic periodic paralysisImportant
- rs121908555A;Gpossibility of Hypokalemic periodic paralysisImportant
- rs751368967C;GSIDS predisposition??Worth knowing
- rs774452124C;TSIDS predisposition??Worth knowing
- rs774453167G;TSIDS predisposition??Worth knowing
Notes
From SNPedia
Notes
rs121908548, also known as c.4765G>A, p.Val1589Met and V1589M, represents a rare mutation in the SCN4A gene on chromosome 17. Based on OMIM, ClinVar designates the mutant allele as pathogenic for paramyotonia congenita, a form of potassium aggravated myotonia that is dominantly inherited. As reported in two families, the clinical description can encompass potassium-aggravated myotonia without muscle weakness and/or cramps in the fingers, toes, and eyelids.
C;T
see rs121908548
Source and license
Adapted from rs121908548 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.