Bruce Wang, MD, a porphyrias specialist and assistant professor in the gastroenterology division in the department of medicine at University of California San Francisco (UCSF) and UCSF Porphyria Center and the Porphyrias Consortium, explains acute hepatic porphyrias (AHPs).
International Porphyria Awareness Week was observed throughout the United States from April 21st through April 28th, and to recognize the effort, Rare Disease Report sat down and spoke with a physician who treats porphyrias: Bruce Wang, MD, a porphyrias specialist and assistant professor in the gastroenterology division in the department of medicine at University of California San Francisco (UCSF) and UCSF Porphyria Center and the Porphyrias Consortium.
Acute hepatic porphyrias (AHPs) are a subgroup of 4 different, rare genetic diseases: acute intermittent porphyria (the most common), variegate porphyria, hereditary coproporphyria, and ALA dehydratase-deficiency porphyrias. All 4 variants are characterized by episodic and potentially life-threatening acute neurologic attacks, which occur most commonly in women in child-bearing years.
“Attacks are typically characterized by very severe, generalized abdominal pain with nausea and vomiting,” explained Dr Wang, “but they can also include other generalized neurological symptoms like numbness, weakness, and other mental status changes.”
In addition to challenging symptoms, AHPs also pose challenging diagnoses. Due to AHPs rarity and the commonality of their symptoms, they are often overlooked and misdiagnosed by physicians. Gallstones, appendicitis, inflammatory bowel disease, irritable bowel syndrome, and fibromyalgia are not uncommon misdiagnoses, and by the time a patient receives an AHPs diagnosis, he or she has often undergone one or multiple abdominal surgeries. As a result, AHPs are often underdiagnosed, and patients can take up to 15 years to receive a proper diagnosis.
There is a very simple urine test to assess an individual for AHPs, Dr Wang explained; however, it requires the physician to consider the potential that it could be the accurate diagnosis and order it.
Regarding treatments, Dr Wang erred on the side of caution, warning that some medications can trigger attacks despite AHPs being genetic diseases.
“The acute attacks typically require additional inciting events,” he said. “Most commonly, these are medications. For example, one of the main triggers known in patients is hormonal changes in women during their menses, which are attacks that may be very difficult to prevent.” When an acute attack has already begun though, there is another therapy that can effectively stop it.
“Giving purified heme proteins infused through the veins stops the acute attack from occurring,” said Dr Wang. “However, there is a need for better medications to prevent patients from having recurrent severe attacks.”
Approximately 10% of AHPs patients experience regular attacks as often as once a week.
A lack of available treatment options is certainly a challenge for individuals suffering from AHP, but an even greater challenge comes when it is realized that the medical field also lacks physicians familiar with AHPs.
“It is, unfortunately, difficult to find physicians who are familiar with this disease,” said Dr Wang. “It is one of the reasons the National Institute of Health has funded a porphyria consortium. We, at the University of California, San Francisco, are 1 of 6 centers that are nationally part of the porphyria consortium, and we have added 3 satellite sites. It can still be very difficult for patients to find a porphyria expert. For over 30 years at UCSF, we have been the only medical center on the West Coast of the US that sees a significant number of porphyria patients.”
In addition to the University of California, San Francisco Porphyria Center, Dr Wang suggested other resources, like the American Porphyria Foundation where patients can turn for resources about research that has been conducted for AHPs, as well as more information about available therapies and ways to prevent acute attacks.