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HSD3B7 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

HSD3B7 gene

The HSD3B7 gene provides instructions for an enzyme in the liver that is vital for the production of bile acids, which are necessary for fat digestion and vitamin absorption.

Normal Function

The HSD3B7 gene provides instructions for making an enzyme called 3 beta-hydroxysteroid dehydrogenase type 7 (3β-HSD7). This enzyme is found in liver cells, embedded in the membrane of the endoplasmic reticulum.

The 3β-HSD7 enzyme is responsible for the second step in the multi-step process of producing bile acids from cholesterol. Bile acids are a component of bile, a digestive fluid that stimulates bile flow and assists in the absorption of fats and fat-soluble vitamins. Specifically, the enzyme converts 7alpha(α)-hydroxycholesterol to 7α-hydroxy-4-cholesten-3-one.

Health Conditions Related to Genetic Changes

Congenital bile acid synthesis defect type 1

At least 17 mutations in the HSD3B7 gene have been found to cause congenital bile acid synthesis defect type 1. This condition is characterized by cholestasis, which impairs the production and release of bile from liver cells.

  • These mutations typically result in a 3β-HSD7 enzyme with little or no function.
  • The impairment prevents the conversion of 7α-hydroxycholesterol, which is instead converted into abnormal bile acid compounds that cannot be transported out of the liver.
  • The buildup of cholesterol and abnormal bile acids in the liver, combined with the inability to absorb fats and fat-soluble vitamins, leads to the signs and symptoms of the condition.

Other Names for This Gene

  • 3 beta-hydroxy-delta 5-C27-steroid oxidoreductase
  • 3 beta-hydroxysteroid dehydrogenase type 7
  • 3 beta-hydroxysteroid dehydrogenase type VII
  • 3-beta-HSD VII
  • 3-beta-hydroxy-Delta(5)-C27 steroid oxidoreductase
  • 3BHS7_HUMAN
  • c(27) 3-beta-HSD
  • C(27)-3BETA-HSD
  • cholest-5-ene-3-beta,7-alpha-diol 3-beta-dehydrogenase
  • SDR11E3
  • short chain dehydrogenase/reductase family 11E, member 3

Frequently Asked Questions

Genetic sequencing of the HSD3B7 gene is the definitive test; it can be done on blood or tissue DNA. In addition, liver function panels, serum bile acid profiling, and a liver biopsy showing abnormal bile acid intermediates support the diagnosis.
The mainstay of therapy is oral bile acid replacement, typically with ursodeoxycholic acid (UDCA) or cholic acid, which bypasses the enzymatic block and improves bile flow. Early initiation often normalizes liver enzymes, reduces cholestasis, and prevents long‑term liver damage. Vitamin supplementation (A, D, E, K) is also required.
Carriers (heterozygotes) are usually asymptomatic because one functional copy of the gene provides enough enzyme activity. However, they have a 25 % chance of having an affected child if both parents are carriers. Genetic counseling is recommended to discuss carrier testing, reproductive options, and prenatal diagnosis.
With consistent bile acid replacement, most patients maintain normal growth and avoid liver failure. Regular follow‑up includes liver function tests every 3–6 months, monitoring of fat‑soluble vitamin levels, and imaging (ultrasound) to assess liver size and fibrosis.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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