Indications: Pyruvate dehydrogenase complex deficiency, typically associated with post-prandial lactic acidemia with a normal lactate/pyruvate ratio, can be assayed in freshly isolated blood lymphocytes, cultured skin fibroblasts, or frozen tissues. The most common defects affect the X-linked E1-alpha subunit, which may be variably expressed especially in females. Measurement in more than one cell type or tissue is recommended because of variable cell/tissue expression with males and females. If low PDC activity is found, the activities of components E1, E2, and E3 are assayed. Gluconeogenic defects of pyruvate carboxylase (more common) and phosphoenolpyruvate carboxykinase (rare) are associated with fasting hypoglycemia and lactic acidosis, and can be assayed in skin fibroblasts or liver.
Method Description: Radioactive enzyme assay measures the rate of decarboxylation of 1-14C-pyruvate, dependent on the presence of thiamine pyrophosphate and coenzyme A, after preactivation or inactivation (by dephosphorylation or phosphorylation) of the enzyme. Assay of the E3 component (dihydrolipoamide dehydrogenase) is used as an internal control for mitochondrial content.
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Specimen |
Specimen Requirements |
Shipping Requirements |
ACD Blood for Lymphocytes |
REQUIRES ADVANCE SCHEDULING
Amt Required varies with patient age.
You will be informed of the required volume when you schedule.
20ml of control blood from an unrelated adult volunteer, drawn at the same time and in the same way as the patient is also REQUIRED!
Collect blood in ACD or CPD-A1 using sterile technique.
*ACD is available in yellow stoppered Vacutainer tubes.
*CPD-A1 is an anticoagulant/preservative mixture used routinely in blood banks.
It is also possible to obtain CPD-A1 in a blood pack unit (from the blood bank), and to then transfer the CPD-A1 to plain sterile Vacutainer tubes. If neither is available, use whatever equivalent mixture is in your blood bank and note this on the sample. Use an equivalent proportion of the mixture/blood sample as would be used routinely in collecting blood.
NOTE:
Yellow stoppered Vacutainer tubes containing SPS, for use in microbiology, are not suitable for enzyme assays.
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Ship tubes in a styrofoam box at room temperature on the day you have scheduled to send the blood to our laboratory with enough packing material, so that the tubes do not crack or break during shipment. Indicate clearly on the container: Room Temperature Do Not Freeze.
If for any reason you are not able to ship on your scheduled day, please notify us.
NOTE:
***We do not accept unscheduled blood, so please contact our laboratory to schedule a shipment time*** |
Cultured Skin Fibroblasts |
REQUIRES ADVANCE SCHEDULING
Two confluent T25 flasks filled to the neck with media in a non-vented flask and tape/parafilm shut. If several assays are ordered (more than 3), the shipment of an additional T25 flask is recommended.
Also the cell line MUST be MYCOPLASMA tested. If your institution is unable to test for mycoplasma, please tell us when you schedule a shipment or send them to Bionique to get tested.
Amt Required: 2T25 flasks |
Schedule a shipment time and ship the 2T25 flasks at room temperature with enough packing material so flasks do not leak.
Please notify us if you are unable to ship the skin fibroblasts on your scheduled shipment time. |
Skin Biopsy |
Biopsy must be obtained under sterile conditions. Be careful to remove all betadine and alcohol and rinse with saline prior to obtaining the sample. Use a 3 or 4mm punch biopsy kit or take from the site of incision for a muscle biopsy.
Place biopsy in a container of sterile Hanks Balance Salt Solution (HBSS), sterile Ringer's Lactate, or other physiological solution.
Minimum Amt Required: a bx punch or a piece |
Call us to let us know you'll be sending the skin biopsy and ship at room temperature with enough packing material so container does not leak.
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Muscle, Heart, or Liver |
After a biopsy/autopsy, the tissue specimen should be immediately quick-frozen in liquid nitrogen.
Minimum Amt Required: 100 mg |
Ship on dry ice. If biopsy/autopsy is performed on a Friday, keep sample at -70°C or colder over the weekend and ship on Monday.
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Samples Accepted: Monday - Friday, 8:30 AM - 5:00 PM
Turn-Around-Time:
2-3 weeks for Skeletal muscle, heart, liver, or blood
lymphocytes
3-4 weeks for skin fibroblasts cultured from T25
7-10 weeks for culturing skin fibroblasts from a skin biopsy
(skin biopsies grow at different rates and sometimes can
take 3 months or longer)
CPT Codes for assay of blood lymphocytes, fibroblasts, or tissues: 84999, 82657, 84157, 80502
CPT Code for lymphocyte preparation: 84999
CPT Codes for Cell Culture: 88233, 88240
CPT Code for Mycoplasma testing if your institution is unable to do this: 86738
Specimens can be sent via Federal Express, DHL, or UPS using Overnight Priority/Next Morning service.
Special Instructions for skin fibroblasts: Ship T25 flasks with Mycoplasma results. Also save back-up flasks of skin fibroblast culture(s) at your institution until you have received the test results in the event of breakage of flasks or contamination during transport.
Future Testing on skin fibroblasts: We freeze down plugs on the cell line(s) you send to us, so if additional testing needs to be ordered in the future, we will have plugs here at CIDEM to initiate.
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