Recurrent Acute Flaccid Quadriparesis: Unmasking Hereditary Coproporphyria after a Diagnostic Odyssey

Background: Acute flaccid paralysis (AFP) is a syndrome of rapid-onset weakness and areflexia, most commonly caused by Guillain-Barr syndrome (GBS).Hereditary coproporphyria (HCP) is a rare, autosomal dominant acute hepatic porphyria that represents a frequently overlooked etiology.Caused by a coproporphyrinogen oxidase (CPOX) gene mutation, HCP leads to the accumulation of neurotoxic porphyrin precursors, causing acute neurovisceral attacks.These attacks can progress to a severe motor neuropathy that mimics AFP.The absence of cutaneous photosensitivity in many cases and the resemblance of its neuropathy to more common conditions often lead to significant diagnostic delay, particularly in patients with recurrent, unexplained weakness. Objectives: To present HCP as a rare, treatable cause of recurrent AFP in children. To highlight the diagnostic challenge and underscore the utility of simple clinical clues, like urine discoloration, in resource-limited settings. To emphasize the critical importance of reanalyzing prior genetic data when clinical suspicion for a specific disorder remains high.Case presentation: A 7-year-old male presented with recurrent acute flaccid quadriplegia, respiratory distress, abdominal pain, vomiting, and severe syndrome of inappropriate antidiuretic hormone secretion (SIADH)-mediated hyponatremia.The diagnostic clue was photosensitive dark-red urine.Prior whole-exome evaluations from outside for tubulopathies were negative.Whole-exome sequencing reanalysis confirmed HCP via a pathogenic CPOX variant (c.746C>G).This case highlights HCP as a rare cause of recurrent AFP.It was initially mismanaged as a tubulopathy before exome sequencing re-analysis identified the correct porphyria diagnosis.Conclusion: This case highlights a classic yet rare presentation of acute neurovisceral porphyria in a pediatric patient and the importance of re-analysis of the exome on strong suspicion.