Pathway candidateNCBI-verifiedprotein-coding

CYP26A1

cytochrome P450 family 26 subfamily A member 1

NCBI Gene: 1592 Ensembl GeneCards UniProt: O43174

Pathway candidate — not linked to PFS or PSSD by any record here

CYP26A1 is in the library because it belongs to the retinoid signaling family. No study, report or commentary in the corpus names it, so a variant in CYP26A1 is not, by itself, evidence of anything related to post-drug syndromes.

Gene summary

A protein-coding gene on chromosome 10 (retinoid signaling). This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This endoplasmic reticulum protein acts on retinoids, including all-trans-retinoic acid (RA), with both 4-hydroxylation and 18-hydroxylation activities.

Source: NCBI Gene and Ensembl, accessed 2026-10-11.

Protein reference (UniProt)

Protein: Cytochrome P450 26A1
Function (excerpt): A cytochrome P450 monooxygenase involved in the metabolism of retinoates (RAs), the active metabolites of vitamin A, and critical signaling molecules in animals. RAs exist as at least four different isomers: all-trans-RA (atRA), 9-cis-RA, 13-cis-RA, and 9,13-dicis-RA, where atRA is considered to be the biologically active isomer, although 9-cis-RA and 13-cis-RA also have activity (Probable). Catalyzes the hydroxylation of atRA primarily at C-4 and C-18, thereby contributing to the regulation of atRA homeostasis and signaling. Hydroxylation of atRA limits its biological activity and initiates a degradative process leading to its eventual elimination (Probable). Involved in the conversion of atRA to all-trans-4-oxo-RA. Able to metabolize other RAs such as 9-cis, 13-cis and 9,13-di-cis RA (By similarity).
Subcellular location: Endoplasmic reticulum membrane; Microsome membrane.
Tissue specificity: Expressed in most fetal and adult tissues with highest levels in adult liver, heart, pituitary gland, adrenal gland, placenta and regions of the brain. Expressed at high levels in lung, pancreas, skin and uterus (at protein level). Lower expression level is detected in spleen, kidney, intestine and adipose tissue (at protein level).

Source: UniProtKB/Swiss-Prot O43174, release 2026_03, licensed CC BY 4.0. This is the protein’s normal biology, not evidence about post-drug syndromes; associated conditions are inherited disorders of the gene, not PFS, PSSD or PRSD.

Why its pathway is in the library

These proteins take vitamin A from blood to gene regulation: RBP4 carries retinol, STRA6 takes it into cells, LRAT stores it, RDH10 and the ALDH1A enzymes turn it into retinoic acid (DHRS3 reverses the first step), CRABP2 carries retinoic acid to the nucleus, the RAR and RXR receptors act on it, and CYP26A1 and CYP26B1 break it down. Isotretinoin, the drug behind post-retinoid sexual dysfunction, is a retinoid; and several retinol dehydrogenases (RDH16, HSD17B6, RDH5) also oxidize androgen metabolites such as 3α-androstanediol, a point of contact with the steroid pathways implicated in PFS.

Written for the whole retinoid signaling family, not for CYP26A1 specifically.

Mentioned in 0 corpus records

No corpus record names CYP26A1 directly yet. It is in the library because it sits in a pathway the corpus tracks (retinoid signaling).

Also in retinoid signaling

All 23 genes

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Gene summary

Source: NCBI Gene and Ensembl, accessed 2026-10-11.

Protein reference (UniProt)

Protein: Cytochrome P450 26A1
Function (excerpt): A cytochrome P450 monooxygenase involved in the metabolism of retinoates (RAs), the active metabolites of vitamin A, and critical signaling molecules in animals. RAs exist as at least four different isomers: all-trans-RA (atRA), 9-cis-RA, 13-cis-RA, and 9,13-dicis-RA, where atRA is considered to be the biologically active isomer, although 9-cis-RA and 13-cis-RA also have activity (Probable). Catalyzes the hydroxylation of atRA primarily at C-4 and C-18, thereby contributing to the regulation of atRA homeostasis and signaling. Hydroxylation of atRA limits its biological activity and initiates a degradative process leading to its eventual elimination (Probable). Involved in the conversion of atRA to all-trans-4-oxo-RA. Able to metabolize other RAs such as 9-cis, 13-cis and 9,13-di-cis RA (By similarity).
Subcellular location: Endoplasmic reticulum membrane; Microsome membrane.
Tissue specificity: Expressed in most fetal and adult tissues with highest levels in adult liver, heart, pituitary gland, adrenal gland, placenta and regions of the brain. Expressed at high levels in lung, pancreas, skin and uterus (at protein level). Lower expression level is detected in spleen, kidney, intestine and adipose tissue (at protein level).

Why its pathway is in the library

Written for the whole retinoid signaling family, not for CYP26A1 specifically.