Four novel mutations in the thiazide-sensitive Na-Cl co-transporter gene in Japanese patients with Gitelman's syndrome.
BACKGROUND
Gitelman's syndrome (GS) is an autosomal recessive disorder resulting from inactivating mutations in the thiazide-sensitive Na-Cl co-transporter (NCCT) gene. To date, almost 90 mutations have been identified. It is possible that there is a population-specific distribution of mutations. In this study, we analysed mutations in the NCCT gene of seven Japanese patients with GS.


METHODS
Peripheral blood mononuclear cells were isolated from patients with GS, their family members and healthy control subjects. A mutation analysis of the NCCT gene was performed completely by direct automated sequencing of polymerase chain reaction-amplified DNA products. In patients with a deletion or splice site mutation, we undertook cDNA sequence analysis.


RESULTS
We identified nine mutations. Five of them [c.185C>T (Thr60Met), c.1712C>T (Ala569Val), c.1930C>T (Arg642Cys), c.2552T>A (Leu849His) and c.1932delC] have been reported in Japanese patients, but not in GS patients from other ethnic groups. The remaining four mutations [c.7A>T (Met1Leu), c.1181_1186+20del26, c.1811_1812delAT and IVS16+1G>A] were novel. In cDNA derived from a patient with c.1181_1186+20del26, a deletion of exon 9 and a frameshift at the start of exon 10 were observed. In cDNA derived from patients with IVS16+1G>A, an additional 96 bp insertion between exons 16 and 17 was observed. Six out of seven patients were compound heterozygotes, and the remaining one carried a single heterozygous mutation.


CONCLUSIONS
We found four novel mutations in the NCCT gene in seven Japanese patients with GS. Moreover, our study suggests that the distribution of mutations in the NCCT gene in Japanese GS patients potentially differs from that in other populations.
Maki
Nobuki
N
Third Department of Internal Medicine, Akita University School of Medicine, Akita, Japan.
Komatsuda
Atsushi
A
Wakui
Hideki
H
Ohtani
Hiroshi
H
Kigawa
Akihiko
A
Aiba
Namiko
N
Hamai
Keiko
K
Motegi
Mutsuhito
M
Yamaguchi
Akihiko
A
Imai
Hirokazu
H
Sawada
Ken-ichi
K
D000328:Adult; D000450:Aldosterone / Q000097:blood*; D000471:Alkalosis / Q000235:genetics*; D002118:Calcium / Q000652:urine*; D004252:DNA Mutational Analysis; D005260:Female; D006579:Heterozygote; D006801:Humans; D007008:Hypokalemia / Q000235:genetics*; D007564:Japan; D008274:Magnesium / Q000097:blood*; D008297:Male; D009154:Mutation; D011955:Receptors, Drug / Q000235:genetics*; D012083:Renin / Q000097:blood*; D049992:Sodium Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics*; D013577:Syndrome
D011955:Receptors, Drug; C578874:SLC12A3 protein, human; D049992:Sodium Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; C064415:thiazide receptor; D000450:Aldosterone; D012083:Renin; D008274:Magnesium; D002118:Calcium