Rs121912805

rs121912805, also known as c.871G>A or p.Glu291Lys, is a mutation in the CLCN1 gene on chromosome 7.

Acting in either an autosomal dominant or recessive manner, the rs121912805(A) allele is considered to cause myotonia congenita; see also OMIM 118425.0010

Note that 23andMe refers to this SNP as i5003258.