Recurrent Severe Viral-Induced Rhabdomyolysis Associated With Underlying Genetic Variants in a Young Adult: A Case Report.

Rhabdomyolysis is a potentially life-threatening syndrome characterized by skeletal muscle breakdown and release of intracellular contents into circulation, which can result in electrolyte abnormalities, acute kidney injury (AKI), and renal failure. Viral infections, particularly influenza, are recognized triggers of rhabdomyolysis; however, recurrent or unusually severe presentations may suggest underlying genetic susceptibility. We report a case of a previously healthy 21-year-old male with a prior history of COVID-19-associated rhabdomyolysis who presented to the emergency department with fever, generalized weakness, myalgia, red urine, and decreased oral intake following influenza A infection. Laboratory evaluation demonstrated severe rhabdomyolysis with creatine kinase (CK) elevation from 512,650 IU/L to a peak of over 1,000,000 IU/L, complicated by pigment-induced AKI requiring temporary hemodialysis. Extensive autoimmune, metabolic, and neuromuscular evaluation was unremarkable. Subsequent genetic testing identified a heterozygous pathogenic STAC3 variant and variants of uncertain significance in SCN4A, PLEC, and MYH7, raising suspicion for an underlying inherited predisposition to recurrent viral-induced muscle injury. This case highlights the importance of considering genetic susceptibility in patients with recurrent or severe viral-induced rhabdomyolysis, particularly in the setting of extreme CK elevation and recurrent episodes.