The ETFQO antibody is a polyclonal rabbit-derived immunoglobulin (IgG) designed to specifically detect the ETFDH protein. Key features include:
This antibody is widely used in immunological assays to study ETFDH’s role in mitochondrial electron transport and its association with metabolic disorders like glutaric aciduria type II (GA2) and multiple acyl-CoA dehydrogenase deficiency (MADD) .
The ETFQO antibody is employed in diverse experimental and clinical contexts:
MADD Diagnosis: Detects pathogenic ETFDH variants (e.g., c.250G>A, c.1067G>A) linked to enzymatic deficiencies .
Mitochondrial Dysfunction: Used to study lipid droplet accumulation and cristae disorganization in ETFDH-deficient tissues .
Therapeutic Monitoring: Assesses riboflavin responsiveness in MADD patients .
Studies highlight critical ETFDH mutations:
c.250G>A: High carrier frequency in Southern China; linked to MADD .
c.1067G>A: Highly pathogenic, causing rapid clinical deterioration in homozygous cases .
c.487+2T>A: Associated with polycystic kidney disease (PKD) via mitochondrial oxidative stress .
Electron Transfer Pathways: The antibody aids in studying the FAD-cluster equilibration that enables UQ reduction .
Alternative Respiration: In etfqo-1 mutants, ETFQO deficiency impairs isovaleryl-CoA dehydrogenase (IVDH) activity under carbon-limiting conditions .
Methodology:
Perform immunoblotting using positive controls (e.g., cell lines or tissues with confirmed ETFQO expression) and negative controls (e.g., CRISPR/Cas9-knockout models) .
Validate via siRNA-mediated knockdown followed by densitometric analysis of band intensity reduction.
Use secondary antibody-only controls to rule out non-specific binding.
Example: In a South African MADD cohort study, ETFQO antibodies were validated using patient-derived fibroblasts and cross-referenced with genetic variants in ETFDH .
Applications:
Diagnosing Multiple Acyl-CoA Dehydrogenase Deficiency (MADD) via immunohistochemistry or Western blotting of patient fibroblasts .
Monitoring treatment efficacy (e.g., riboflavin supplementation) by quantifying ETFQO protein levels pre- and post-intervention .
Investigating mitochondrial fatty acid oxidation pathways in model organisms.
Protocol:
Conduct checkerboard titrations (e.g., 1:500 to 1:2000 dilutions) using lysates from tissues with varying ETFQO expression levels.
Adjust based on signal-to-noise ratios; the MADD study used 1:1000 dilutions in immunoblotting .
Include normalization to housekeeping proteins (e.g., β-actin) for quantitative comparisons.
Mitigation Strategies:
Validate each batch using standardized controls (e.g., recombinant ETFQO protein).
Document lot numbers and compare inter-batch performance via coefficient of variation (CV) analysis.
Reference: Studies highlight up to 30% variability in signal intensity across antibody batches, particularly with polyclonal preparations .
Resolution Workflow:
Compare subcellular fractionation protocols (e.g., differential centrifugation vs. digitonin permeabilization).
Use orthogonal methods (e.g., immunofluorescence microscopy + mitochondrial markers) to confirm localization.
Example: Conflicting reports of ETFQO in cytosol vs. mitochondria may stem from tissue-specific isoforms or fixation artifacts .
Approach:
Troubleshooting Table:
| Issue | Potential Cause | Solution |
|---|---|---|
| No signal | Low ETFQO expression | Use high-sensitivity substrates (e.g., chemiluminescent) |
| Faint bands | Over-transfer or degradation | Optimize gel electrophoresis time; add protease inhibitors |
| Non-specific bands | Cross-reactivity | Pre-absorb antibodies with antigen-blocking peptides |
Analytical Framework:
Apply multivariate regression to adjust for confounders (e.g., age, treatment status).
Use meta-analysis tools (e.g., RevMan) to harmonize data from heterogeneous studies.
Reference: The SA MADD cohort employed segregation analysis and haplotype frequency calculations to reconcile genetic and biochemical data .
Workflow:
Design Considerations: