 NCC harboring type II mutations have normal kinetic properties but are present in lower amounts at the cell surface, resulting in a decreased uptake of sodium and chloride.NCC harboring type II mutations is still under control of its modulators and can still increase or decrease its activity in response to stimuli, whereas type I mutations cause a complete loss of function and regulation of the cotransporter.However, in some patients with Gitelman's syndrome, no mutations in the NCC gene have been found despite extensive genetic work-up.