Genetic Analysis of Gitelman Syndrome: Co-existence with Hyperthyroidism in a Two-year-old Boy

Case Presentation: A two-year-old boy visited the doctor for hypokalemia and metabolic alkalosis. Laboratory examination revealed that urinary potassium excretion and serum aldosterone level were increased, with hyperthyroidism and thyroid-related antibodies positive at the same time. Genetic testing showed that there was a complex heterozygous mutation in the SLC12A3 gene, c.1077C>G (p.N359K) and c.1567G>A (p.A523?); the final diagnosis was Gitelman syndrome and autoimmune hyperthyroidism. Background: Gitelman syndrome is an autosomal recessive genetic disease caused by the inactivation of mutation of the SLC12A3 gene. The onset age is more than 6 years old; it is mainly manifested as low blood potassium, low blood sodium, low blood chlorine, metabolic alkalosis, increased urine potassium and urine chlorine excretion, and low urine calcium. Autoimmune hyperthyroidism manifests due to autoimmune disorders. The highest incidence rate in children is of Graves' disease, followed by chronic lymphocytic thyroiditis. Conclusion: