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Test ID PMMIL Phosphomannomutase and Phosphomannose Isomerase, Leukocytes

Useful For

Diagnosing congenital disorders of glycosylation Ia (phosphomannomutase-2 deficiency: PMM2-CDG) and Ib (phosphomannose isomerase deficiency: MPI-CDG) as measured in leukocytes

 

Follow-up testing for patients with an abnormal type I CDG transferrin isoform profile

 

This test is not useful for carrier testing.

Genetics Test Information

Congenital disorders of glycosylation (CDG) are a large and growing group of inborn errors of glycan metabolism that are clinically diverse, but most often present during infancy or childhood.

 

A diagnostic workup for a CDG should begin with transferrin analysis by liquid chromatography-mass spectrometry (CDG / Carbohydrate Deficient Transferrin for Congenital Disorders of Glycosylation, Serum).

 

Follow-up testing of an abnormal type 1 CDG transferrin isoform profile may include enzymatic analysis for the diagnosis of phosphomannomutase-2 deficiency (PMM2-CDG) and phosphomannose isomerase deficiency (MPI-CDG).

Method Name

Colorimetric

Reporting Name

PMM-PMI, Leukocytes

Specimen Type

Whole Blood ACD


Ordering Guidance


The initial screening test for congenital disorders of glycosylation is transferrin isoform analysis (CDG / Carbohydrate Deficient Transferrin for Congenital Disorders of Glycosylation, Serum). The results of the transferrin isoform analysis should be correlated with the clinical presentation to determine the most appropriate testing strategy, which may include this test.



Shipping Instructions


For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.



Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A)

Specimen Volume: 6 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD Refrigerated (preferred) 6 days YELLOW TOP/ACD
  Ambient  6 days YELLOW TOP/ACD

Reference Values

PHOSPHOMANNOMUTASE

Normal >350 nmol/h/mg protein

 

PHOSPHOMANNOSE ISOMERASE

Normal >1,300 nmol/h/mg protein

Day(s) Performed

Preanalytical processing: Monday through Saturday

Assay performed: Twice per month

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82657

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PMMIL PMM-PMI, Leukocytes 100735-0

 

Result ID Test Result Name Result LOINC Value
50836 Specimen 31208-2
50837 Specimen ID 57723-9
50838 Source 31208-2
50839 Order Date 82785-7
50840 Reason For Referral 42349-1
50841 Method 85069-3
50842 Phosphomannomutase, Leuko 78970-1
50843 Phosphomannose Isomerase, Leuko 78963-6
50844 Interpretation 59462-2
50845 Amendment 48767-8
50846 Reviewed By 18771-6
50847 Release Date 82772-5

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

Report Available

30 to 45 days

NY State Approved

Yes

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602) in Special Instructions

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Testing Algorithm

For more information see Congenital Disorders of Glycosylation: Screening Algorithm.