--- Query Results ---

  
Program:Genetics and Genomics
 
Test Name:Very Long-Chain & Branched-Chain Fatty Acids (G&G South ACH)
Test Code:VLCFA-P, VLCFA-S
Performing Site: Alberta Children's Hospital
Performing Dept:Biochemical Genetics
 
Availability:Test is performed on a monthly basis.
TAT:45 days
 
Preferred Tube/Container:Sodium heparin (dark green - NOT PST)
Alternate:Lithium heparin (dark green - NOT PST)
Non-additive (red top - NOT SST)
 
Specimen Requirements:1. Collect 1 x 4.0 mL sodium heparin tube (or alternate tube type).
2. Collect following a minimum four-hour fast; or just before next feed for newborns.
3. Indicate length of fast, or time of last feeding on the requisition (with collection time).
 
Min. Sample Required:0.25 mL plasma or serum
 
Specimen Processing:At ACH only
The primary heparinized tube can be put on ice (ensure not to freeze sample) or refrigerated for routine pick-ups between 8:30 am – 2:30 pm, Monday through Friday.

For all other collections
1. Centrifuge.
2. Transfer plasma or serum to aliquot tube.
3. Write "NaHep", "LiHep" or "Red Top" on the aliquot tube label.
4. Freeze.
 
Specimen Handling:Transport frozen samples on ice. Samples must not thaw during transport.
 
Additional Information:
  1. Dietary Restrictions
    • Patients should avoid eating peanut-rich goods (e.g., peanut butter) 24 hours prior to collection.
  2. Samples will be rejected if:
    • Primary tube not refrigerated
    • Aliquot tube received thawed
    • Tube type not written on aliquot tube label
 
Requisition/Form:Submit request using Biochemical Genetics Laboratory Requisition.
Please ensure all required information, including patient's clinical history/indication, is provided on the requisition.
 
Order Restrictions:None
 
Indications:This test is for the investigation of peroxisomal biogenesis disorders and specific peroxisomal fatty-acid oxidation disorders.
This test should be ordered in combination with plasma/serum or urine pipecolic acid for the investigation of a peroxisomal biogenesis disorders as an additional, independent measure of peroxisomal function.

This test SHOULD NOT be ordered for the investigation of very long chain acyl-CoA dehydrogenase deficiency, as the enzyme deficiency in that disorder is involved in mitochondrial (not peroxisomal) fatty acid beta-oxidation.
Method:Saturated very long-chain and branched-chain fatty acids are detected following derivatization (i.e., silylation) using a gas chromatography-mass spectrometry (GC-MS) stable isotope dilution (SID) method with deuterium-labeled internal standards.
Method Details:Disorders Detectable by very long-chain and branched-chain fatty acid analysis*:
  1. Peroxisomal Biogenesis Disorders
    • Zellweger spectrum disorder (encompassing Zellweger syndrome, NALD and infantile Refsum disease)
  2. Specific Peroxisomal Enzyme Deficiencies:
    • X-linked adrenoleukodystrophy
    • acyl-CoA oxidase deficiency (a.k.a., pseudo-NALD)
    • D-bifunctional protein deficiency
    • 2-methylacyl-CoA racemase deficiency
    • Adult Refsum disease
*Further confirmatory testing is required for some of these conditions, as nonspecific/artifactual findings as well as overlapping patterns may prevent definitive diagnosis in specific cases.

Metabolite reported:
  • behenic (docosanoic) acid (C22:0), lignoceric (tetracosanoic) acid (C24:0), ceratinic (hexacosanoic) acid (C26:0), pristanic (2,6,10,14-tetramethylpentadecanoic) acid, phytanic (3,7,11,15-tetramethylhexadecanoic) acid.
  •  
    Reference Interval:
    C22:0   33 - 96umol/L
    C24:0   25 - 79umol/L
    C26:00.22 - 1.08umol/L
    C26:0/C22:0   <0.020  ratio
    C24:0/C22:00.44 - 1.16  ratio
    Phytanic Acid    <11.5umol/L
    Pristanic Acid     <1.5umol/L
     
    Comments:For the investigation of very long chain acyl-CoA dehydrogenase deficiency, order Acylcarnitine Profile (ACH).

    Contact ACH Biochemical Genetics Laboratory (403-955-7379) for priority turn-around.
     
     
    Last Updated On:Monday, March 26, 2018
    Date of Last Review:Jan 2 2018 12:00AM