We present the case of a Mexican woman who started experiencing recurring episodes of intense abdominal pain, weakness in her upper and lower extremities, uncontrollable vomiting, and insomnia at the age of 17. These symptoms required frequent visits to the emergency department. Despite undergoing normal biochemical and imaging tests, not responding to pain relief medications, and even undergoing abdominal surgery for suspected acute appendicitis, her symptoms persisted. After enduring nearly three years of almost daily symptoms, an episode of elevated urine porphobilinogen during a crisis finally confirmed the diagnosis of acute intermittent porphyria.

Treatment with hematin derivatives (Normosang®, Panhematin®) was initiated, resulting in partial improvement. However, subsequent years witnessed progressively severe crises, some accompanied by paralysis and kidney injury. Remarkably, elevated urine porphobilinogen was even detected during asymptomatic periods. Notably, her first cousin also received a diagnosis of acute intermittent porphyria with a similar clinical presentation.

A molecular genetic study was conducted at a reference center in Belgium. All coding exons (1, 3-15), including parts of the adjacent intronic sequences and regions of the 5´- and 3´-UTR of the HMBS gene, were PCR-amplified from genomic DNA. The amplicons underwent direct sequencing using capillary electrophoresis and the BigDye technology (Applied Biosystems). Data alignment and comparison with the wildtype sequence (NM_000190.3) were performed using the GenBank Database. This analysis revealed a heterozygous state mutation, c.457C>T (p.Q153, exon 9, HMBS gene).

At the age of 28, she enrolled in a clinical trial for Givosiran, an RNA interference therapeutic targeting ALAS1 mRNA. Remarkably, she exhibited a remarkable response to the treatment and continued it even after the trial. Over the past years, her symptoms have been sporadic, and she has not required hospitalization.