A novel SLC12A3 splicing mutation skipping of two exons and preliminary screening for alternative splice variants in human kidney.
BACKGROUND
Gitelman's syndrome is a mild autosomal recessive disorder caused by inactivating mutations of SLC12A3. However, severe phenotype may be associated with compound heterozygous nonfunctional variants such as frameshift and splicing mutations. Because most multi-exon genes are alternatively spliced as shown by recent studies, SLC12A3, with 26 exons, is likely to be alternatively spliced as well.


METHODS
A case of Gitelman's syndrome with both physical and mental retardation was investigated by genetic analysis. In addition, the alternative splice variants of SLC12A3 were screened by RT-PCR.


RESULTS
A novel intron 7 and exon 8 boundary mutation (a successive 13-nucleotide transition: intron 7 as -1 G>A plus exon 8 +1 to +12 delCGGACATTTTTGinsCCGAAAATTTT) was identified in this patient besides a missense mutation Thr60Met. Further cDNA analysis revealed the novel mutation led to skipping of exons 7 and 8. Furthermore, we found an aberrant splice product skipping of exon 7 and identified two high-abundance alternative splice transcripts.


CONCLUSIONS
This is the first report of a splice mutation of SLC12A3 with multiple-exon skipping in Gitelman's syndrome. This study provides further evidence for the severe phenotype of Gitelman's syndrome and its association with underlying mutations. Additionally, we demonstrated that the pre-mRNA of SLC12A3 was complex spliced.
Shao
Leping
L
Division of Nephrology, Affiliated Hospital of Qingdao University School of Medicine, Qingdao, PR China.
Liu
Liqiu
L
Miao
Zhimin
Z
Ren
Hong
H
Wang
Weiming
W
Lang
Yanhua
Y
Yue
Shaoheng
S
Chen
Nan
N
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D004252:DNA Mutational Analysis; D005091:Exons; D006801:Humans; D007438:Introns; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D011955:Receptors, Drug / Q000235:genetics* / Q000378:metabolism*; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics* / Q000378:metabolism*
D011955:Receptors, Drug; C578874:SLC12A3 protein, human; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters