One study reporting dominant dRTA mutations in the SLC4A1 gene found that, despite phenotypic similarities, the R901X mutation caused a milder phenotype than the R598H mutation, including lower plasma bicarbonate concentration and more severe hypokalemia, in patients with the R589H mutation than in those with the R901X mutation (Karet et al., 1998). This evidence concerns the gene SLC4A1 and Hypokalemia.