Alpha 1 Antitrypsin Phenotype (Sendout)

General Information

Lab Name

Alpha 1 Antitrypsin Phenotype

Lab Code

RA1AP

Epic Name

Alpha-1 Antitrypsin Phenotype (Sendout)

External Test Id

A1APP

Description

Useful for: Identification of homozygous and heterozygous phenotypes of the alpha-1-antitrypsin deficiency. Refer to guidance below.

Ordering Recommendation:

Initial Testing:
- Recommended First Step: perform Alpha 1 Antitrypsin [A1AT].
- Include CRP, high sensitivity [HSCRP] to check for an acute phase response.
  - Note: An acute phase response can elevate a genetically low A1AT, potentially confounding results.
If CRP is High:
- If CRP is high and the A1AT is low, wait for inflammation to resolve before measuring again.
If A1AT is Low with Non-elevated (i.e. normal) CRP:
- Proceed to classify the decrease with Mayo proteotype test (mass spectrometry, Alpha 1 Antitrypsin Type S/Z (Sendout) [RA1APR]).
  - Mayo Alpha-1-Antitrypsin Comprehensive Testing Algorithm
  - This test will determine if the decrease is due to a common mutation (Z/S).
- If the mass spectrometry proteotype assay is inconclusive, phenotyping (isoelectric focusing, this test) will be performed reflexively.
Last Resort:
- Consider full SERPINA1 gene sequencing for unusual cases (to order sequencing, contact the Laboratory Medicine Resident via the paging operator at 206-598-6190).

Synonyms

A1A Phenotyping, A1APP, A1AT Phenotype, AAT Phenotyping, Pi Typing, Protease Inhibitor Allo Typing

Components

Code	Name
PHENO	Alpha 1 Antitrypsin Phenotype
RA1A	Alpha 1 Antitrypsin, Total

Interpretation

Method

A1AT Phenotype: Isoelectric Focusing
A1AT: Nephelometry

Reference Range

See individual components

Ref. Range Notes

Interpretation:

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.

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 Caucasians 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.

Interferences and Limitations

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.

Ordering & Collection

Specimen Type: Blood
Collection: 4 mL blood in GOLD SST or RED TOP tube
Approval Required: LMR approval is not required.
Handling Instructions: Outside Laboratories: Centrifuge sample and transfer serum to a separate aliquot. Refrigerate serum.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 28 days.

Reject Due To: Gross lipemia. Gross hemolysis and gross icterus are acceptable.
Quantity: Requested: 1 mL serum
Minimum: 0.3 mL serum

Processing

Receiving Instructions

Centrifuge sample and aliquot serum to a separate plastic vial. Refrigerate serum.

Sendouts:

Order Mayo Test: A1APP.
Interfaced: Yes.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 28 days.

Reject Due To: Gross lipemia. Gross hemolysis and gross icterus are acceptable.

Misc Sendout

Performance

Lab Department

Sendouts Mayo Lab (RF)(MARF)

Frequency

Performed: Sun-Sat. Report Available: 2-6 days from sample receipt at Mayo Clinic Laboratories.

Available STAT?

Performing Location(s)

Sendout	Mayo Clinic Laboratories 800-533-1710 200 First Street Southwest Rochester, MN 55901

Billing & Coding

CPT Codes: 82103, 82104
LOINC: 32769-2
Interfaced Order Code: UOW3741