[Acute intermittent porphyria]

Acute intermittent porphyria is an autosomal dominant disease caused by a mutation in the gene coding for the porphobilinogen deaminase enzyme in the haem biosynthesis. The prevalence varies geographically.

This article presents a literature-based review of acute intermittent porphyria with emphasis on epidemiology and diagnostic and therapeutic strategies.

The 50% reduced activity of porphobilinogen deaminase enzyme found in heterozygote persons is sufficient for basal conditions, but during attacks, stimulation of haem synthesis upstream produces toxic spillover products that give a purple colour to the urine. Many causes: common drugs, alcohol, starvation, pregnancy or menstruation, can lead to attacks of abdominal pain, motor and/or sensory polyneuropathy autonomic dysfunction, hyponatraemia, mental changes and seizures. Hepatic carcinoma may develop in older patients with acute intermittent porphyria. Acute attacks are treated with glucose or haem arginate intravenously. Preliminary results indicate a prevalence of 600/100,000 for acute intermittent porphyria in the municipality of Saltdal in Norway compared to 1-2/100,000 in Europe generally. A W198X mutation is found in the porphobilinogen deaminase enzyme gene in members of a family in Saltdal, shared by some families in northern Sweden.

The high prevalence of acute intermittent porphyria in specific geographic areas emphasizes the importance of correct diagnosis, the first crucial step in avoiding attacks and associated diseases.