The First Korean Case of SLC12A3 Aberrant Skipping of Two Exons Detected by RNA Splicing Analysis

Gitelman syndrome is a salt-losing tubular disorder that is transmitted as an autosomal recessive trait. Variants in the SLC12A3 gene are found in the majority of Gitelman syndrome patients. A 26-year-old woman visited the genetic counseling clinic. Her fiancé was a known Gitelman syndrome patient who was previously diagnosed with 2 pathogenic variants in SLC12A3. In advance of marriage and future family planning, she wanted to perform genetic testing of SLC12A3. A silent exonic variant c.1050G>A was found, and multiple splice site in silico algorithms predicted this variant to have potential alteration of splicing. This variant was classified as "variant of uncertain significance,"and RNA splicing analysis was additionally performed. RNA splicing analysis showed aberrant splicing of exon 7-8 skipping. The result points out the potential pathogenicity of this variant, which should be considered a candidate of variant reclassification in the future. We highly recommend the performance of additional RNA splicing analysis, especially for silent variants predicted to have potential alteration of splicing.