Unusual presentation of thrombotic microangiopathy in a young adult

Thrombotic Microangiopathy (TMA) is a complex disorder encompassing various acquired and hereditary causes. In this case report, we delve into the atypical presentation of TMA in a 21-year-old patient, characterized by a distinctive lack of systemic findings (e.g., thrombocytopenia and microangiopathic hemolytic anemia) typically associated with the condition. An extensive investigation ruled out common etiologies, including ADAMTS13 deficiency (ruling out TTP), Shiga-toxin mediated HUS, and other secondary causes such as drug/immune-related factors, toxins, and systemic complement dysregulation (aHUS). A comprehensive genetic panel for complement mutations was negative. The patient's medical history did not align with prior COVID-19 infection, eliminating a potential causative link. The patient's lack of hypertension history raised a perplexing question: did renal disease precede hypertension or vice versa? Renal biopsy revealed characteristic features of TMA with mesangial deposits, hinting at a potential underlying genetic cause. However, common hereditary culprits, such as complement factor H mutations or Cobalamin C abnormalities, were ruled out through meticulous clinical, serological, and genetic evaluation. • A 21-year-old female with hypertensive emergency and acute renal failure, no prior hypertension history. • Extensive testing excluded common TMA causes, including ADAMTS13 deficiency, infections, and autoimmune disorders. • Renal biopsy revealed mesangial deposits, and genetic causes like complement factor H mutations were excluded.