Since mutations in the SLC12A3 and CLCNKB genes are not present in all patients with clinical manifestations of Gitelman syndrome, genetic screening after clinical diagnosis is essential.
This study revealed the following characteristics of these disorders: 1) subjects with CLCNKB mutations showed one or more biochemical features of Gitelman syndrome (including hypomagnesemia, hypocalciuria, and fractional chloride excretion insensitivity to thiazide administration); and 2) subjects with KCNJ1 mutations appeared to show normal fractional chloride excretion sensitivity to furosemide and thiazide administration.
We searched for SLC12A3 and CLCNKB gene mutations in 13 Chinese patients (9 males and 4 females, age 35 +/- 14 years) from 8 unrelated families with the clinical and biochemical features of GS.
However, the relationship between the alterations in the NO signalling system observed in this study and the mutations in either Na+-K+-2Cl cotransporter or in a K+ channel ROMK or in Cl- channel ClCNKB in Bartter's syndrome and in Na+-Cl- cotranstransporter in Gitelman's syndrome, recently reported as their primary defects remains to be defined.