7-Dehydrocholesterol reductase, also known as DHCR7, is a protein that in humans is encoded by the DHCR7 gene. [5] [6] [7]
7-Dehydrocholesterol reductase, also known as DHCR7, is a protein that in humans is encoded by the DHCR7 gene. [5] [6] [7]
| 7-dehydrocholesterol reductase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 1.3.1.21 | ||||||||
| CAS no. | 9080-21-1 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
The protein encoded by this gene is an enzyme catalyzing the production of cholesterol from 7-Dehydrocholesterol using NADPH.
The DHCR7 gene encodes delta-7-sterol reductase (EC 1.3.1.21), the ultimate enzyme of mammalian sterol biosynthesis that converts 7-dehydrocholesterol (7-DHC) to cholesterol. This enzyme removes the C(7-8) double bond introduced by the sterol delta8-delta7 isomerases. In addition, its role in drug-induced malformations is known: inhibitors of the last step of cholesterol biosynthesis such as AY9944 and BM15766 severely impair brain development. [5]
A deficiency is associated with Smith–Lemli–Opitz syndrome. [8]
All house cats and dogs have higher-than-usual activity of this enzyme, causing an inability to synthesize vitamin D due to the lack of 7-dehydrocholesterol. [9]
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D3 in the skin, therefore functioning as provitamin-D3. The presence of this compound in human skin enables humans to manufacture vitamin D3 (cholecalciferol). Upon exposure to ultraviolet UV-B rays in the sun light, 7-DHC is converted into vitamin D3 via previtamin D3 as an intermediate isomer. It is also found in the milk of several mammalian species. Lanolin, a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by sunlight and then ingested during grooming as a nutrient. In insects 7-dehydrocholesterol is a precursor for the hormone ecdysone, required for reaching adulthood. It was discovered by Nobel-laureate organic chemist Adolf Windaus.
Smith–Lemli–Opitz syndrome is an inborn error of cholesterol synthesis. It is an autosomal recessive, multiple malformation syndrome caused by a mutation in the enzyme 7-Dehydrocholesterol reductase encoded by the DHCR7 gene. It causes a broad spectrum of effects, ranging from mild intellectual disability and behavioural problems to lethal malformations.
XX gonadal dysgenesis is a type of female hypogonadism in which the ovaries do not function to induce puberty in an otherwise normal girl whose karyotype is found to be 46,XX. With nonfunctional streak ovaries, she is low in estrogen levels (hypoestrogenic) and has high levels of FSH and LH. Estrogen and progesterone therapy is usually then commenced. Some cases are considered a severe version of premature ovarian failure where the ovaries fail before puberty.
Laminopathies are a group of rare genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina. They are included in the more generic term nuclear envelopathies that was coined in 2000 for diseases associated with defects of the nuclear envelope. Since the first reports of laminopathies in the late 1990s, increased research efforts have started to uncover the vital role of nuclear envelope proteins in cell and tissue integrity in animals.
Mevalonate kinase is an enzyme that in humans is encoded by the MVK gene. Mevalonate kinases are found in a wide variety of organisms from bacteria to mammals. This enzyme catalyzes the following reaction:
A dysmorphic feature is an abnormal difference in body structure. It can be an isolated finding in an otherwise normal individual, or it can be related to a congenital disorder, genetic syndrome or birth defect. Dysmorphology is the study of dysmorphic features, their origins and proper nomenclature. One of the key challenges in identifying and describing dysmorphic features is the use and understanding of specific terms between different individuals. Clinical geneticists and pediatricians are usually those most closely involved with the identification and description of dysmorphic features, as most are apparent during childhood.
Methionine synthase reductase, also known as MSR, is an enzyme that in humans is encoded by the MTRR gene.
MID1 is a protein that belongs to the Tripartite motif family (TRIM) and is also known as TRIM18. The MID1 gene is located on the short arm of the X chromosome and loss-of-function mutations in this gene are causative of the X-linked form of a rare developmental disease, Opitz G/BBB Syndrome.
Peroxisome biogenesis factor 1, also known as PEX1, is a protein which in humans is encoded by the PEX1 gene.
24-Dehydrocholesterol reductase is a protein that in humans is encoded by the DHCR24 gene.
Lathosterol oxidase is a Δ7-sterol 5(6)-desaturase enzyme that in humans is encoded by the SC5D gene.
Acrocallosal syndrome is an extremely rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features, motor and intellectual disabilities, and other symptoms. The syndrome was first described by Albert Schinzel in 1979. Mutations in KIF7 are causative for ACLS, and mutations in GLI3 are associated with a similar syndrome.
Hydrolethalus syndrome (HLS) is a rare genetic disorder that causes improper fetal development, resulting in birth defects and, most commonly, stillbirth.
Desmosterolosis in medicine and biology is a defect in cholesterol biosynthesis. It results in an accumulation of desmosterol and a variety of associated symptoms. Only two cases have been reported as of 2007. The condition is due to inactivating mutations in 24-dehydrocholesterol reductase. Certain anticholesterolemic and antiestrogenic drugs such as triparanol, ethamoxytriphetol, and clomifene have been found to inhibit conversion of desmosterol into cholesterol and to induce desmosterolosis, for instance cataracts.
Lathosterolosis is an inborn error of cholesterol biosynthesis caused by a deficiency of the enzyme 3-beta-hydroxysteroid-delta-5-desaturase. This leads to a flaw in the conversion of lathosterol to 7-dehydrocholesterol. Characteristics include facial dysmorphism, congenital malformations, failure to thrive, developmental delay, and liver illness. Brunetti-Pierri et al. originally described Lathosterolosis in 2002.
Young–Madders syndrome, alternatively known as Pseudotrisomy 13 syndrome or holoprosencephaly–polydactyly syndrome, is a genetic disorder resulting from defective and duplicated chromosomes which result in holoprosencephaly, polydactyly, facial malformations and intellectual disability, with a significant variance in the severity of symptoms being seen across known cases. Many cases often suffer with several other genetic disorders, and some have presented with hypoplasia, cleft lip, cardiac lesions and other heart defects. In one case in 1991 and another in 2000 the condition was found in siblings who were the product of incest. Many cases are diagnosed prenatally and often in siblings. Cases are almost fatal in the prenatal stage with babies being stillborn.
C-5 sterol desaturase is an enzyme that is highly conserved among eukaryotes and catalyzes the dehydrogenation of a C-5(6) bond in a sterol intermediate compound as a step in the biosynthesis of major sterols. The precise structure of the enzyme's substrate varies by species. For example, the human C-5 sterol desaturase oxidizes lathosterol, while its ortholog ERG3 in the yeast Saccharomyces cerevisiae oxidizes episterol.
A sterol-sensing domain (SSD) is a protein domain which consists of 180 amino acids forming five transmembrane segments capable of binding sterol groups. This type of domain is present in proteins involved in cholesterol metabolism and signalling.
John M. Opitz was a German-American medical geneticist and professor at the University of Utah School of Medicine. He is best known for rediscovering the concept of the developmental field in humans and for his detection and delineation of many genetic syndromes, several now known as the "Opitz syndromes" including Smith–Lemli–Opitz syndrome (SLOS), Opitz–Kaveggia syndrome (FGS1), Opitz G/BBB syndrome, Bohring–Opitz syndrome, and other autosomal and X-linked conditions. He is founder of the Wisconsin Clinical Genetics Center, the American Journal of Medical Genetics, and was a cofounder of the American College and American Board of Medical Genetics.
A steroidogenesis inhibitor, also known as a steroid biosynthesis inhibitor, is a type of drug which inhibits one or more of the enzymes that are involved in the process of steroidogenesis, the biosynthesis of endogenous steroids and steroid hormones. They may inhibit the production of cholesterol and other sterols, sex steroids such as androgens, estrogens, and progestogens, corticosteroids such as glucocorticoids and mineralocorticoids, and neurosteroids. They are used in the treatment of a variety of medical conditions that depend on endogenous steroids.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
