SLC12A3 is a gene that provides instructions for making a protein called the sodium-chloride cotransporter. This protein is primarily found in the kidneys, where it plays a crucial role in reabsorbing sodium and chloride ions from urine back into the bloodstream. This process helps regulate electrolyte balance and blood pressure. Mutations in the SLC12A3 gene can lead to a condition known as Gitelman syndrome, which is characterized by low levels of potassium and magnesium in the blood, as well as metabolic alkalosis. Individuals with this condition may experience muscle cramps, weakness, and fatigue due to electrolyte imbalances.