Distribution of African-American and French-Canadian men and women according to NKCC activity. The 50 µmol/liter cells/h increment of NKCC was used to calculate the percentage of patients with the carrier’s activity, indicated by white and black circles (French-Canadian and African-American women, respectively) and white and black squares (French-C anadian and African-American men, respectively). AA-M, African-American men; AA-W, African-American women; FC-M, French-Canadian men; FC-W, French-Canadian women; NKCC, Na+,K+,2Cl− co-transport.