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HelpEpic Code LAB1230724 Alpha-1-Antitrypsin Phenotype, Serum
Additional Codes
Mayo code: A1APP
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Identification of homozygous and heterozygous phenotypes of the alpha-1-antitrypsin deficiency
Specimen Type
SerumSpecimen Required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1.25 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
COLLECTION NOTE: Volumes listed are in serum or plasma, draw approximately 2 1/2 times the requested volume in whole blood.
Special Instructions
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Day(s) Performed
Monday through Friday
Reference Values
ALPHA-1-ANTITRYPSIN
100-190 mg/dL
ALPHA-1-ANTITRYPSIN PHENOTYPE
The interpretive report will identify the alleles present. For rare alleles, the report will indicate whether or not they have been associated with reduced quantitative levels of alpha-1-antitrypsin.
Clinical Information
Alpha-1-antitrypsin (A1A) is the most abundant serum protease inhibitor and inhibits trypsin and elastin, as well as several other proteases. The release of proteolytic enzymes from plasma onto organ surfaces and into tissue spaces results in tissue damage unless inhibitors are present. Congenital deficiency of A1A is associated with the development of emphysema at an unusually early age and with an increased incidence of neonatal hepatitis, usually progressing to cirrhosis.
Most normal individuals have the M phenotype (M, M1, or M2). Over 99% of M phenotypes are genetically MM. In the absence of family studies, the phenotype (M) and quantitative level can be used to infer the genotype (MM). The most common alleles associated with a quantitative deficiency are Z and S.
See Alpha-1-Antitrypsin-A Comprehensive Testing Algorithm in Special Instructions.
Cautions
This assay identifies the phenotype of the circulating alpha-1-antitrypsin (A1A) protein. If the patient is already on replacement therapy, the phenotype will detect patient and replacement protein.
If 2 bands are seen, such as an M band and a Z bands, it is reported as MZ (eg, heterozygous)
If 1 band is seen, such as the Z band and the quantitative level is consistent with a homozygote, the phenotype is assumed to be homozygous and is reported as ZZ.
Interpretation
There are greater than 40 alpha-1-antitrypsin (A1A) phenotypes (most of these are associated with normal quantitative levels of protein). The most common normal phenotype is M (M, M1, or M2), and greater than 90% of individuals of European descent are genetically homozygous M (MM).
A1A deficiency is usually associated with the Z phenotype (homozygous ZZ), but SS and SZ are also associated with decreased A1A levels.
Reporting Name
Alpha-1-Antitrypsin PhenotypeMethod Name
A1AP2: Isoelectric Focusing
AATP: Nephelometry
Method Description
Phenotyping is done by isoelectric focusing in agarose gels.(Package insert: Hydragel 18 A1AT Isofocusing. Sebia. 2013 July)
Nephelometry.(Instruction manual: Siemens Nephelometer II. Siemens, Inc., Newark, DE)
CPT Code Information
82103
82104
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| A1APP | Alpha-1-Antitrypsin Phenotype | 32769-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| AATP | Alpha-1-Antitrypsin, S | 6771-0 |
| 8166 | Alpha-1-Antitrypsin Phenotype | 32769-2 |
Report Available
2 to 6 daysTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.Clinical Reference
1. Morse JO: Alpha-1-antitrypsin deficiency. N Engl J Med 1978;299:1045-1048;1099-1105
2. Donato LJ, Jenkins SM, Smith C, et al: Reference and interpretive ranges for alpha(1)-antitrypsin quantitation by phenotype in adult and pediatric populations. Am J Clin Pathol 2012 Sep;138(3):398-405
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| A1AP2 | Alpha-1-Antitrypsin Phenotype | No | Yes |
| AATP | Alpha-1-Antitrypsin, S | Yes, (Order AAT) | Yes |
Forms
If not ordering electronically, complete, print, and send Gastroenterology and Hepatology Test Request (T728) with the specimen.