Recovery of chronic motor neuropathy due to acute intermittent porphyria after givosiran treatment in a young boy: a case report

BACKGROUND: We describe the first case of a pediatric patient with acute intermittent porphyria and severe chronic porphyric neuropathy treated with givosiran, a small-interfering RNA that drastically decreases delta-aminolevulinic acid production and reduces porphyric attacks’ recurrence. CASE REPORT: A 12-year-old male patient with refractory acute intermittent porphyria and severe porphyric neuropathy was followed prospectively for 12 months after givosiran initiation (subcutaneous, 2.5 mg/kg monthly). Serial neurological, structural, and resting-state functional magnetic resonance imaging (MRI) evaluations were performed, including clinical scales and neurophysiological tests. Delta-aminolevulinic acid urinary levels dropped drastically during treatment. In parallel, all the administered neurological rating scales and neurophysiological assessments showed improvement in all domains. Moreover, an improvement in central motor conduction parameters and resting-state functional connectivity in the sensory- motor network was noticed. At the end of the follow-up, the patient could walk unaided after using a wheelchair for 5 years. CONCLUSIONS: A clear beneficial effect of givosiran was demonstrated in our patient with both clinical and peripheral nerve neurophysiologic outcome measures. Moreover, we first reported a potential role of givosiran in recovering central motor network impairment in acute intermittent porphyria (AIP), which was previously unknown. This study provides Class IV evidence that givosiran improves chronic porphyric neuropathy.