ACUTE PORPHYRIA - BUT WHICH ONE?

A 36-year-old woman was admitted to our center with tetraparesis, assisted breathing, red urine and hyponatremia (113 mmol/l). Starting one month earlier she experienced weakness, increasing colicky abdominal pain and developed paralytic ileus and tetraparesis. Biochemical studies revealed increased porphyrin precursors (porphobilinogen: 348 µmol/l, aminolevulinic acid: 114 µmol/l) and porphyrins (uroporphyrin: 237 nmol/l, coproporphyrin: 3161 nmol/l) in the urine indicating acute porphyric attack. The patient improved for hematine therapy, after 6 months of physical therapy she was able to walk again and had no symptoms. To identify the type of her acute porphyria HPLC analysis of the feces was carried out. The result did not indicate the presence of coproporphyria or variegate porphyria. Later the coproporphyrinogen oxydase and protoporphyrinogen oxydase activities were measured in the French Porphyria Center in Paris and were within the normal range. The aminolevulinic acid dehydratase activity was normal too. The hydroxymethylbilane synthase activity was high (150% of the normal level) which occurs during an acute attack as it was reported in the literature, but it remained high even years later (97% of the normal level). The porphobilinogen level in the urine also remained elevated. These findings suggested the non-erythroid form of acute intermittent porphyria. According to this exon 1, its boundaries and the promoter region of the hydroxymethylbilane synthase gene were sequenced in both direction but no mutation was detected. The aim of this presentation was to show a case where the usual diagnostic laboratory methods failed to identify the type of acute porphyria making impossible to screen the family members for this disease. [The genetic study of this work was supported by the Hungarian Ministry of Welfare (ETT 025/2000)].