Renal Hypouricemia Type 2 due to a Novel Homozygous SLC2A9 Variant: Exercise‐Induced Acute Kidney Injury in One of Two Affected Siblings

We present the case of an adult male with repeated episodes of post-exercise acute renal injury. His biochemical study revealed severe hypouricemia with very high fractional excretion of urate and a genetic study showed the presence of an undescribed homozygous variant: SLC2A9 c.999T > G (p.N333K). A study of the parents, who were clinically healthy, normouricemic, and non-consanguineous, revealed that they carried the same variant in heterozygosis. Of the patient's two sisters, one is healthy and homozygous for the reference allele, while the other, who exhibits the same homozygous variant as the index case, presents with hypouricemia but remains asymptomatic. This is likely attributable to her physical inactivity, a consequence of severe uncorrected hip dysplasia. The present study aims to shed light on the pathogenic potential of this variant, not previously described in Latin Americans, illustrating the pathophysiological sequence that originates from the genetic change in renal uric acid management and its relationship with physical exercise and consequent acute kidney injury (AKI).