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HelpTest Code LAB3790 Mitochondrial Respiratory Chain Enzyme Analysis (ETC)
Clinical System Name
Mitochondrial Respiratory Chain Enzyme Analysis (ETC)
Synonyms
Mitochondrial ETC
Electron Transport Chain
Mito ETC
Sample Requirements
Specimen: Muscle Tissue
Container(s): see notes
Preferred Vol:100 mg fresh weight
Minimum Vol: May be able to accept smaller specimens, please contact the laboratory for approval.
Note: A 1 x 0.5 x 0.5 cm sample dissected from the belly of the muscle along the longitudinal plane should be obtained with minimal trauma and no cautery. Sample should be IMMEDIATELY transported to pathology OC.8.901 for weighing and flash freezing in liquid nitrogen.
Samples collected at outside hospitals should be flash frozen in liquid nitrogen within 20 minutes of resection and stored at -70C until shipping on dry ice to Seattle Children’s Laboratory, see “Off-Site collection” Instructions below.
Processing Instructions
Reject due to:
Spin: N
Aliquot:N
Temp:Frozen
Storage location:
Biopsies collected at Seattle Children’s hospital, notify Histology immediately when specimen arrives in Lab. Contact on-call pathologist if Histology is unavailable.
Samples received at the community service bench should be kept frozen and stored in -70 BG freezer.
Off-site collection: Samples should be flash frozen in liquid nitrogen within 20 minutes of resection, minimizing expose to heat. Store samples at -70C until ready to ship. Ship samples Monday-Thursday on dry ice with overnight delivery.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Tissue | Room temp |
20 min |
| On Ice |
20 min |
|
|
Frozen at -70°C or colder |
10 yr |
Availability
| STAT | Performed | TAT |
|---|---|---|
| N | monthly | 4 weeks |
Muscle biopsies should be scheduled between 0700 and 1500, Mon - Fri at SCH main campus.
Contact the Biochemical Genetics Lab for requests outside of stated availability (206) 987-2216.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Biochemical Genetics
Phone Number: 206-987-2216
CPT Codes
82657
Methodology
Method: UV-Vis absorbance to measure enzyme function over time.
Reference Range
Nine reactions are performed to test functionality of complexes 1-4 as well as citrate synthase and lactate dehydrogenase, for sample quality assurance.
|
Enzyme |
Ref Range (nmol/min/mg) |
Mean (nmol/min/mg) |
95% Confidence Interval |
|
Complex 1 |
>8 |
23 |
8-38 |
|
Complexes 1 and 3 |
>7 |
22 |
7-37 |
|
Complex 2 |
>26 |
59 |
26-92 |
|
Succinate Dehydrogenase |
>19 |
118 |
19-218 |
|
Complex 3 |
>14 |
47 |
14-80 |
|
Complexes 2 and 3 |
>9 |
25 |
9-42 |
|
Complex 4 |
>37 |
120 |
37-204 |
|
Citrate Synthase |
>79 |
237 |
79-394 |
|
Lactate Dehydrogenase |
>575 |
2178 |
575-3782 |
Description
The purpose of this assay is to identify malfunctioning electron transport chain complexes to support clinical evaluation of a defect in energy production. Testing is intended for patients with mitochondrial disease as part of their differential diagnosis for whom neuromuscular pathological evaluation may be ambiguous, DNA analysis was uninformative or identified variants of uncertain clinical significance. Functional enzyme testing may provide supporting evidence for a diagnosis of mitochondrial disease.