HSD3B7 gene

hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 7

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. It is embedded in the membrane of a cell structure called the endoplasmic reticulum, which is involved in protein processing and distribution. The 3β-HSD7 enzyme participates in the production of bile acids, which are a component of a digestive fluid called bile. Bile acids stimulate bile flow and helps absorb fats and fat-soluble vitamins. Bile acids are produced from cholesterol in a multi-step process. The 3β-HSD7 enzyme is responsible for the second step in that process, which converts 7alpha(α)-hydroxycholesterol to 7α-hydroxy-4-cholesten-3-one.

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, a condition that impairs the production and release of a digestive fluid called bile from liver cells. Most of the HSD3B7 gene mutations delete one or two DNA building blocks (base pairs) from the gene or replace single protein building blocks (amino acids) in the enzyme. These mutations result in production of a 3β-HSD7 enzyme with little or no function. Without enough functional 3β-HSD7 enzyme, the conversion of 7α-hydroxycholesterol to 7α-hydroxy-4-cholesten-3-one is impaired. The 7α-hydroxycholesterol instead gets converted into abnormal bile acid compounds that cannot be transported out of the liver into the intestine, where the bile acids are needed to absorb fats and fat-soluble vitamins. This impaired production and release of bile acids leads to cholestasis. As a result, cholesterol and abnormal bile acids build up in the liver and fat-soluble vitamins are not absorbed, leading to the signs and symptoms of congenital bile acid synthesis defect type 1.

Cytogenetic Location: 16p11.2, which is the short (p) arm of chromosome 16 at position 11.2

Molecular Location: base pairs 30,985,189 to 30,989,152 on chromosome 16 (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: 16p11.2, which is the short (p) arm of chromosome 16 at position 11.2
  • 3-beta-HSD VII
  • 3 beta-hydroxy-delta 5-C27-steroid oxidoreductase
  • 3-beta-hydroxy-Delta(5)-C27 steroid oxidoreductase
  • 3 beta-hydroxysteroid dehydrogenase type 7
  • 3 beta-hydroxysteroid dehydrogenase type VII
  • 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