Acute intermittent porphyria
How often do people with acute intermittent porphyria have attacks?
Most people with acute intermittent porphyria will only have 1 or a few attacks throughout their life. About 5% of people with this condition will have 'recurrent' attacks, which means more than 4 attacks per year.
Acute Intermittent Porphyria. Gene Reviews. (http://www.ncbi.nlm.nih.gov/books/NBK1193)