SC5D Gene - Sterol-C5-Desaturase
Key enzyme in cholesterol biosynthesis, associated with lathosterolosis and neurodevelopmental disorders
Gene Information Card
| Symbol | SC5D |
|---|---|
| Full Name | Sterol-C5-Desaturase |
| Gene Type | Protein coding |
| Chromosomal Location | 11q23.3 |
| NCBI Gene ID | 6309 ncbi.nlm.nih.gov/gene/6309 |
| Ensembl ID | ENSG00000109919 |
| UniProt ID | O75845 |
| OMIM ID | 602286 |
| HGNC ID | 10547 |
| Aliases | SC5DL, S5DES, ERG3, delta-5-desaturase |
Description
The SC5D gene encodes sterol-C5-desaturase, an enzyme in the cholesterol biosynthesis pathway that catalyzes the conversion of lathosterol to 7-dehydrocholesterol. Mutations in SC5D cause lathosterolosis, a rare autosomal recessive disorder characterized by multiple congenital anomalies, intellectual disability, and elevated lathosterol levels. The enzyme is localized to the endoplasmic reticulum and requires cytochrome b5 as a cofactor.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Lathosterolosis | Loss-of-function mutations in SC5D impair conversion of lathosterol to 7-dehydrocholesterol, leading to accumulation of lathosterol and deficiency of downstream sterols including cholesterol. This disrupts membrane integrity and signaling pathways. | OMIM #607330; ClinVar; multiple case reports (PMID: 11971868, 12414899) |
| Neurodevelopmental disorder with hypotonia and dysmorphic features | Biallelic SC5D variants cause a syndromic form of intellectual disability with hypotonia, microcephaly, and facial dysmorphism, likely due to cholesterol deficiency during brain development. | ClinVar; PMID: 28418390 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | High |
| Adrenal gland | 8.3 | Medium |
| Brain | 6.1 | Medium |
| Testis | 4.7 | Low |
| Kidney | 3.9 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 14.2 | Hepatocellular carcinoma cell line |
| SH-SY5Y | 7.8 | Neuroblastoma cell line |
| HEK293 | 6.5 | Embryonic kidney cells |
| HeLa | 5.1 | Cervical carcinoma cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.638G>A (p.Arg213Gln) | Missense | Rare | Loss of function; reduced enzyme activity (PMID: 11971868) |
| c.1042C>T (p.Arg348Trp) | Missense | Rare | Loss of function; associated with lathosterolosis (ClinVar) |
| c.1A>G (p.Met1Val) | Start loss | Rare | Loss of function; no protein expression (PMID: 28418390) |
| c.1180delC (p.Leu394Trpfs*12) | Frameshift | Rare | Loss of function; premature truncation (ClinVar) |
Mutation functional classification
Loss of Function (LOF)
Most reported SC5D mutations are loss-of-function, leading to reduced or absent enzyme activity and accumulation of lathosterol.
Gain of Function (GOF)
No gain-of-function mutations have been reported for SC5D.
Dominant Negative (DN)
No dominant-negative mutations have been described; disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• KEGG hsa00100: Steroid biosynthesis
• Reactome R-HSA-191273: Cholesterol biosynthesis
• Reactome R-HSA-8957322: Metabolism of steroids
Protein Summary
Sterol-C5-desaturase (UniProt O75845) is a 299-amino acid enzyme located in the endoplasmic reticulum membrane. It contains a histidine-rich motif characteristic of membrane-bound desaturases and requires cytochrome b5 and iron for activity. The enzyme catalyzes the introduction of a double bond at the C5 position of lathosterol, a key step in the Kandutsch-Russell pathway of cholesterol synthesis. Deficiency leads to lathosterolosis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SC5D Knockout HEK293 Cell Line | EDJ-KQ5713 | Human | 6309 | Details Get a Quote |
| SSC5D Knockout HEK293 Cell Line | EDJ-KQ15515 | Human | 284297 | Details Get a Quote |
| SC5D Knockout A-549 Cell Line | EDJ-KQ29092 | Human | 6309 | Details Get a Quote |
| SC5D Knockout HCT 116 Cell Line | EDJ-KQ29093 | Human | 6309 | Details Get a Quote |
| SC5D Knockout HeLa Cell Line | EDJ-KQ29094 | Human | 6309 | Details Get a Quote |
| SSC5D Knockout HeLa Cell Line | EDJ-KQ46332 | Human | 284297 | Details Get a Quote |
| SSC5D Knockout A-549 Cell Line | EDJ-KQ67912 | Human | 284297 | Details Get a Quote |
| SSC5D Knockout HCT 116 Cell Line | EDJ-KQ76291 | Human | 284297 | Details Get a Quote |
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