The Signs and Symptoms of AIP Are Difficult to Recognize
The clinical features of an acute attack of acute intermittent porphyria (AIP) vary greatly.3 The most common symptom is severe abdominal pain.1 Other neurovisceral and circulatory disturbances may occur.12 These clinical manifestations are all due to effects on the nervous system.*12
* Adapted from Anderson KE, Bloomer JR, Bonkovsky HL, et al. Recommendations for the diagnosis and treatment of the acute porphyrias. Ann Intern Med. 2005;142:439-450.
Incidence of Common Signs and Symptoms of Acute Intermittent Porphyria*1
* Data compiled from several series of patients with symptomatic acute intermittent porphyria.
AIP Is a Rare Disease
The combined prevalence of the 4 acute porphyrias, of which AIP is one, is estimated to be approximately 5 cases per 100,000 people in the US.1 Exact estimation is difficult as the majority of people with the gene mutation for AIP remain asymptomatic, and others may have only one or a few acute attacks throughout life.1
Genetic Patterns in AIP
While AIP is inherited as an autosomal dominant trait, the family history may not be indicative of the disease because most individuals do not present symptoms of the disease.1 Up to 200 different mutations have been identified in the porphobilinogen (PBG) deaminase gene, responsible for the deficient enzyme that results in AIP.12
In AIP there is an inherited partial deficiency (approximately 50% of normal) of PBG deaminase which predisposes the affected person to the effects of precipitating factors, all of which can increase the demand for hepatic heme, and thus induce synthesis of aminolevulinic acid (ALA) synthase.1,12 Due to a downstream deficiency of PBG deaminase, there is a marked accumulation and urinary excretion of PBG and ALA.1 How this leads to the symptomatic disease is still unclear.1,12