HMBS
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Gene summaries condense public reference material; disease links and population data change as databases are updated. Clinical decisions belong with your care team.
hydroxymethylbilane synthase
Normal Function
Health Conditions Related to Genetic Changes
Porphyria
More than 300 mutations in the HMBS gene have been identified in people with a form of porphyria known as acute intermittent porphyria. Some of these mutations change single protein building blocks (amino acids) in hydroxymethylbilane synthase. Other mutations add or delete genetic material within the HMBS gene, which alters the structure and function of the enzyme.
Mutations in the HMBS gene reduce the activity of hydroxymethylbilane synthase, allowing compounds called porphyrins to build up in the liver and other organs. These compounds are formed during the normal process of heme production, but reduced activity of hydroxymethylbilane synthase allows them to accumulate to toxic levels. This buildup, in combination with nongenetic factors such as certain drugs, alcohol, smoking, and dieting, leads to attacks of severe abdominal pain and other symptoms in people with acute intermittent porphyria.
More About This Health ConditionRelated Conditions
Porphyria
Health Conditions Related to Genetic Changes
More than 300 mutations in the HMBS gene have been identified in people with a form of porphyria known as acute intermittent porphyria. Some of these mutations change single protein building blocks (amino acids) in hydroxymethylbilane synthase. Other mutations add or delete genetic material within the HMBS gene, which alters the structure and function of the enzyme.
Mutations in the HMBS gene reduce the activity of hydroxymethylbilane synthase, allowing compounds called porphyrins to build up in the liver and other organs. These compounds are formed during the normal process of heme production, but reduced activity of hydroxymethylbilane synthase allows them to accumulate to toxic levels. This buildup, in combination with nongenetic factors such as certain drugs, alcohol, smoking, and dieting, leads to attacks of severe abdominal pain and other symptoms in people with acute intermittent porphyria.