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THURSDAY, Aug. 25 (HealthDay News) -- Researchers have discovered a molecular missing link that helps explain why fasting brings on acute attacks of the genetic disease hepatic porphyria.
Porphyria disease is caused by defects in the enzyme pathway that produces heme, a critical iron compound found in red blood cells, according to a report in the Aug. 26 issue of Cell. The intermediate molecules that eventually become heme accumulate in the body, becoming toxic.
Acute porphyria attacks can cause such symptoms as severe abdominal pain, skin sensitivity to sunlight, and psychiatric disorders including hysteria.
Doctors have long known that fasting can cause acute attacks of the disease, and that the attacks can be relieved with glucose or other high-carbohydrate treatments.
Now, a team from the Dana-Farber Cancer Institute and Harvard Medical School has found that fasting increases levels of a metabolic protein called PGC-1a. The protein jump-starts the process of creating glucose from scratch in the liver, but it also regulates the activity of a key enzyme in the production of heme.
The higher levels of that enzyme can cause a toxic buildup of precursor heme molecules, the team found.
More information
The National Institute of Diabetes and Digestive and Kidney Diseases has more about porphyria (digestive.niddk.nih.gov ).
--Dennis Thompson
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