A New Case of Kilquist's Syndrome with a Novel Variant in SLC12A2 and a Brief Review of the Literature

Background Kilquist's syndrome is a recently described rare disease characterized by hearing loss, secretory dysfunction, gastrointestinal system abnormalities, and neurological anomalies including hypotonia and global developmental delay. It is caused by mutations in the solute carrier family 12 member 2 (SLC12A2) gene, which encodes the Na-K-2Cl cotransporter isoform 1 (NKCC1). Objective The aim of this study was to contribute to understanding the genotype–phenotype correlations of SLC12A2 variants. Material and Methods We evaluated a Turkish patient with a novel variant in SLC12A2 and reviewed all previously reported cases with Kilquist's syndrome. Whole exome sequencing and Sanger sequencing were used as molecular genetic testing methods. Results Whole exome sequencing revealed a nonsense homozygous NM_001046.3: c.2534G > A (pW845*) variant in the SLC12A2 gene. Sanger sequencing confirmed the variant. The patient was homozygous for this variant; the parents were heterozygous. Conclusion This is the first Turkish patient with a novel variant in SLC12A2 reported in the literature. With this report, we have contributed to expanding the clinical and mutation spectrum of SLC12A2.