Pathway candidateNCBI-verifiedprotein-coding

HSD17B4

hydroxysteroid 17-beta dehydrogenase 4

NCBI Gene: 3295 Ensembl GeneCards UniProt: P51659

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

HSD17B4 is in the library because it belongs to the steroid synthesis family. No study, report or commentary in the corpus names it, so a variant in HSD17B4 is not, by itself, evidence of anything related to post-drug syndromes.

Gene summary

A protein-coding gene on chromosome 5 (steroid hormone synthesis). The protein encoded by this gene is a bifunctional enzyme that is involved in the peroxisomal beta-oxidation pathway for fatty acids. It also acts as a catalyst for the formation of 3-ketoacyl-CoA intermediates from both straight-chain and 2-methyl-branched-chain fatty acids.

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: Peroxisomal multifunctional enzyme type 2
Function: Bifunctional enzyme acting on the peroxisomal fatty acid beta-oxidation pathway. Catalyzes two of the four reactions in fatty acid degradation: hydration of 2-enoyl-CoA (trans-2-enoyl-CoA) to produce (3R)-3-hydroxyacyl-CoA, and dehydrogenation of (3R)-3-hydroxyacyl-CoA to produce 3-ketoacyl-CoA (3-oxoacyl-CoA), which is further metabolized by SCPx. Can use straight-chain and branched-chain fatty acids, as well as bile acid intermediates as substrates. May play a role in peroxisomal beta-oxidation step in polyunsaturated fatty acids (PUFAs) biosynthesis. Possibly regulates systemic levels of docosahexaenoic acid (DHA, C22:6n-3) through a process involving endoplasmic reticulum desaturation and elongation of alpha-linolenic acid (ALA, C18:3n-3) to form tetracosahexaenoic acid (THA, C24:6n-3), which is then beta-oxidized to DHA in peroxisomes.
Pathway: Lipid metabolism; fatty acid beta-oxidation.
Subcellular location: Peroxisome.
Tissue specificity: Present in many tissues with highest concentrations in liver, heart, prostate and testis.
Associated conditions: D-bifunctional protein deficiency (DBPD); Perrault syndrome 1 (PRLTS1).

Source: UniProtKB/Swiss-Prot P51659, 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

Steroid-synthesis enzymes sit directly on the pathways perturbed by 5-alpha-reductase inhibitors and SSRIs; inherited variation here is a candidate susceptibility factor for persistent post-drug phenotypes.

Written for the whole steroid synthesis family, not for HSD17B4 specifically.

Mentioned in 0 corpus records

No corpus record names HSD17B4 directly yet. It is in the library because it sits in a pathway the corpus tracks (Steroid synthesis).

Also in steroid hormone synthesis

All 38 genes

Browse by family on the gene families page.

Gene summary

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: Peroxisomal multifunctional enzyme type 2
Function: Bifunctional enzyme acting on the peroxisomal fatty acid beta-oxidation pathway. Catalyzes two of the four reactions in fatty acid degradation: hydration of 2-enoyl-CoA (trans-2-enoyl-CoA) to produce (3R)-3-hydroxyacyl-CoA, and dehydrogenation of (3R)-3-hydroxyacyl-CoA to produce 3-ketoacyl-CoA (3-oxoacyl-CoA), which is further metabolized by SCPx. Can use straight-chain and branched-chain fatty acids, as well as bile acid intermediates as substrates. May play a role in peroxisomal beta-oxidation step in polyunsaturated fatty acids (PUFAs) biosynthesis. Possibly regulates systemic levels of docosahexaenoic acid (DHA, C22:6n-3) through a process involving endoplasmic reticulum desaturation and elongation of alpha-linolenic acid (ALA, C18:3n-3) to form tetracosahexaenoic acid (THA, C24:6n-3), which is then beta-oxidized to DHA in peroxisomes.
Pathway: Lipid metabolism; fatty acid beta-oxidation.
Subcellular location: Peroxisome.
Tissue specificity: Present in many tissues with highest concentrations in liver, heart, prostate and testis.
Associated conditions: D-bifunctional protein deficiency (DBPD); Perrault syndrome 1 (PRLTS1).