Laboratory Test Information Guide

Details for Alpha 1-Antitrypsin Phenotype, Serum

Test Name: Alpha 1-Antitrypsin Phenotype, Serum
Alternate Name(s): A1AT Phenotyping
Alpha-1-Antitrypsin:Proteotype
Laboratory: Core
Specimen Type: 5 mL Gold top Vacutainer tube

Pediatric:
0-2 years: Red 0.5 pk.
2-10 years 2 mL Red top
Collection Information: Minimum volume required is 1.5 mL for an adult sample and 0.5 mL for a pediatric sample.

Serum drawn from a fasting individual is preferred.
Requisition: GENERAL LABORATORY REQUISITION
Test Schedule: Referred out as required
Turnaround time from when specimen
is received in testing laboratory:
 
Routine
20 days
Stat
N/A
 
Reference Range: Alpha-1-Antitrypsin: 100- 190 mg/dL (Mayo medical Lab reference range)
Proteotype: Negative for S and Z phenotype (Non S Non Z)
Effective Date: 2010-01-21
Revised Date: 2017-06-30
Critical Value:  
Interpretive Comments: Report includes S Mutation, Z Mutation, Proteotype Comment, serum A1AT level, and A1AT phenotype comment.

This assay will not detect 5% of the known mutations that cause A1AT deficiency
Special Processing: This test is available exclusively to LHSC/SJHC physicians.

All specimens submitted for A1AT Phenotyping will have a serum A1AT level performed at LHSC as a screening tool. Those specimens with an A1AT result of ≤1.50 g/L will be subject to review by the Biochemist for authorization.
Comments: For each of the possible genotypes there is an expected range for the total serum level of A1AT. However, a number of factors can influence either the A1AT serum level or the proteotype results, including acute illness (acute phase reactant), protein replacement therapy, the presence of other rare variants, or the presence of DNA polymorphisms. When the serum level differs from what is expected for that proteotype (i.e. discordant), additional studies are performed to ensure the most appropriate interpretation of test results. Additional follow-up may include A1AT phenotyping by isoelectric focusing (IEF), obtaining additional clinical information and DNA sequencing.
Method of Analysis: Nephelometry: quantification of serum A1AT levels.
LC-MS/MS (Proteotype): detection of the mutated peptides of the S and Z alleles.
IEF (Phenotyping): determination of specific allelic variants.
Critical Information Required:  
Storage & Shipment: Store sample at 2-8C for up to 5 days.
If sample must be stored for longer, store specimen at -20C or below.
Avoid repeated freeze/thaw cycles.
System Codes: 
Cerner
A1ATP
 
Referred To: Referred out to Mayo Medical Laboratories via ICL.

The testing lab has revised their protocol for this test. A1AT Phenotyping by isoelectronic focusing (IEF) will not be offered as a stand-alone test. All orders for A1AT Phenotyping will be processed using a new primary test, Alpha-1-Antitrypsin:Proteotype (A1ALC). Phenotyping by IEF will only be offered as a reflex add-on if the Proteotype and serum level are discordant.

Questions? Comments? Contact Laura Gopaul