Hydroxymethylbilane Synthase Gene Mutation: The Hidden Driver of Abdominal Pain and Neurological Symptoms in Acute Intermittent Porphyria

Abstract

Mutations in the hydroxymethylbilane synthase (HMBS) gene can lead to a deficiency of the HMBS enzyme, allowing porphyrins to accumulate to toxic levels in the liver and other organs, leading to acute intermittent porphyria (AIP). This case report describes the medical journey of a 20-year-old female, previously in good health, who experienced multiple hospitalizations and clinic visits due to severe abdominal pain episodes and remained undiagnosed for over 6 years. Despite the nonspecific nature of these symptoms, a suspicion of acute porphyria confirmed by genetic analysis revealed a splice pathogenic variant (c.826-2A>T) in the HMBS gene in a heterozygous state. As the disease progressed, the patient developed a series of complications, including hyponatremia, autonomic instability, and motor neuropathy, culminating in complete paralysis (quadriplegia) and respiratory failure. The case highlights the importance of early recognition and differential diagnoses in managing AIP, with genetic testing playing a crucial role in confirming the diagnosis.

Keywords

• acute intermittent porphyria
• case report
• hydroxymethylbilane synthase gene