CPT1B

Chr 22

carnitine palmitoyltransferase 1B

Also known as: CPT1-M, CPT1M, CPTI, CPTI-M, M-CPT1, MCCPT1, MCPT1

NCBI Gene: 1375ENSG00000205560UniProt: Q92523

The protein encoded by this gene, a member of the carnitine/choline acetyltransferase family, is the rate-controlling enzyme of the long-chain fatty acid beta-oxidation pathway in muscle mitochondria. This enzyme is required for the net transport of long-chain fatty acyl-CoAs from the cytoplasm into the mitochondria. Multiple transcript variants encoding different isoforms have been found for this gene, and read-through transcripts are expressed from the upstream locus that include exons from this gene. [provided by RefSeq, Jun 2009]

311
ClinVar variants
145
Pathogenic / LP
0.00
pLI score
1
Active trials
Clinical Summary— CPT1B
⚡
Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
📋
ClinVar Variants
145 Pathogenic / Likely Pathogenic· 145 VUS of 311 total submissions
💊
Clinical Trials
1 active or recruiting trial — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
Tolerant — LoF & missense variants common in population
LoF Constraint?LOEUF (Loss-of-function Observed/Expected Upper bound Fraction) is the upper bound of the 90% CI for LoF OE — the preferred gnomAD v4 metric. Lower = more intolerant to LoF. LOEUF < 0.35 = highly constrained.
0.83LOEUF
pLI 0.000
Z-score 2.44
OE 0.59 (0.42–0.83)
Tolerant

Typical tolerance to LoF variation

Missense Constraint?Missense Z-score: standard deviations fewer missense variants observed vs. expected. Z > 3.09 (p < 0.001) = gene does not tolerate missense variation. OE missense < 0.6 is also considered constrained.
0.49Z-score
OE missense 0.94 (0.87–1.01)
449 obs / 479.5 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?Shaded band = 90% confidence interval. Vertical tick = point estimate. Grey threshold line = gnomAD constraint cutoff for that variant class.
LoF OE?Ratio of observed to expected LoF variants. Upper CI bound (LOEUF) ≤ 0.35 = strong LoF constraint signal.0.59 (0.42–0.83)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.94 (0.87–1.01)
0≤0.61.4
Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.0.98
0≤1.21.6
LoF obs/exp: 24 / 40.8Missense obs/exp: 449 / 479.5Syn Z: 0.25

ClinVar Variant Classifications

311 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic144
Likely Pathogenic1
VUS145
Likely Benign9
Benign9
144
Pathogenic
1
Likely Pathogenic
145
VUS
9
Likely Benign
9
Benign

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
0
144
0
144
Likely Pathogenic
0
0
1
0
1
VUS
1
126
18
0
145
Likely Benign
0
4
3
2
9
Benign
0
1
5
3
9
Total11311715308

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

Protein Context — Lollipop Plot

CPT1B · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

OMIM — Genotype-Phenotype Relationships

1 OMIM entry

OMIM
Clinical Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
CPT1A-mediated Fat Oxidation, Mechanisms, and Therapeutic Potential.
Schlaepfer IR et al.·Endocrinology
2020Review
PPARγ agonist pioglitazone reverses pulmonary hypertension and prevents right heart failure via fatty acid oxidation.
Legchenko E et al.·Sci Transl Med
2018
Pharmacological inhibition of miR-126 enhances venetoclax activity in acute myeloid leukemia.
Zhang L et al.·Blood
2026
CPT1B, a metabolic molecule, is also an independent risk factor in CN-AML.
Ling Q et al.·Cancer Biomark
2023
Single nucleotide polymorphism in CPT1B and CPT2 genes and its association with blood carnitine levels in acute myocardial infarction patients.
Khan HA et al.·Gene
2013Cohort
Cryptotanshinone alleviates liver fibrosis via inhibiting STAT3/CPT1A-dependent fatty acid oxidation in hepatic stellate cells.
Li Z et al.·Chem Biol Interact
2024
Variant between CPT1B and CHKB associated with susceptibility to narcolepsy.
Miyagawa T et al.·Nat Genet
2008
MT1G induces lipid droplet accumulation through modulation of H3K14 trimethylation accelerating clear cell renal cell carcinoma progression.
Wang S et al.·Br J Cancer
2024
International Union of Basic and Clinical Pharmacology. CXIX. Fundamental insights and clinical relevance regarding the carnitine palmitoyltransferase family of enzymes.
Rodríguez-Rodríguez R et al.·Pharmacol Rev
2025Review
HucMSC-Exo Induced N2 Polarization of Neutrophils: Implications for Angiogenesis and Tissue Restoration in Wound Healing.
Yang J et al.·Int J Nanomedicine
2024
Top 10 resultsSearch PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
DHDK, a Plant-Derived Natural Small Molecule, Protects Against Doxorubicin-Induced Cardiotoxicity via the PPARG-CPT1B-FAO Axis.
Hong J et al.·Pharmaceuticals (Basel)
2025🔓 Open Access
CPT1B-Mediated Fatty Acid Oxidation Induces Pigmentation in Solar Lentigo.
Choi Y et al.·Pigment Cell Melanoma Res
2025
The TEX44-CPT1B axis regulates mitochondrial sheath assembly and fatty acid oxidation in sperm.
Zhi E et al.·Nat Commun
2025🔓 Open Access
Shared molecular profiles of post-laser vision correction ectasia and keratoconus with key differences in CADPS, CPT1B, CIITA, and TBC1D4.
Jaskiewicz-Rajewicz K et al.·Front Mol Biosci
2025🔓 Open Access
AAV-mediated overexpression of CPT1B protects from cardiac hypertrophy and heart failure in a murine pressure overload model.
Kliesow Remes A et al.·Basic Res Cardiol
2025🔓 Open AccessFunctional
Top 5 resultsSearch Europe PMC ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov
Klinefelter Syndrome

Interrogating Fatty Acid Metabolism Impairment and Clinical Correlates in Males with Klinefelter Syndrome

ACTIVE NOT RECRUITING
NCT05498090Phase PHASE4University of Colorado, DenverStarted 2022-11-03
Fenofibrate 145 mg

External Resources

Links to major genomics databases and tools