CPT1B
Chr 22carnitine palmitoyltransferase 1B
Also known as: CPT1-M, CPT1M, CPTI, CPTI-M, M-CPT1, MCCPT1, MCPT1
CPT1B encodes carnitine palmitoyltransferase IB, the rate-controlling enzyme that catalyzes the transfer of long-chain fatty acids onto carnitine for mitochondrial uptake and subsequent beta-oxidation in muscle. Mutations cause CPT1B deficiency, an autosomal recessive disorder presenting with exercise intolerance, muscle weakness, and rhabdomyolysis triggered by prolonged exercise or fasting. The gene shows low constraint against loss-of-function variants, consistent with the recessive inheritance pattern of this fatty acid oxidation disorder.
No known disease relationship
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Typical tolerance to LoF variation
Mild missense constraint
The highest-scoring mechanism for this gene is dominant-negative.
Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.
Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.
ClinVar Variant Classifications
200 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | 0 | 0 | 127 | 0 | 127 |
Likely Pathogenic | 0 | 0 | 1 | 0 | 1 |
VUS | 2 | 44 | 12 | 0 | 58 |
Likely Benign | 0 | 3 | 3 | 0 | 6 |
Benign | 0 | 0 | 5 | 3 | 8 |
| Total | 2 | 47 | 148 | 3 | 200 |
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.
3D Protein StructureAlphaFold
External Resources
Links to major genomics databases and tools
Clinical Trials
Active and recruiting trials from ClinicalTrials.gov
No active trials found for this gene.
Search ClinicalTrials.gov →External Resources
Links to major genomics databases and tools