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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.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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.  Pre-analytical processing is performed Monday through Friday and Sunday. This test may be canceled if specimens are outside of stability when processing occurs. Collect and package specimens for arrival on days when processing is performed.



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 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 Friday, Sunday

Assay performed: Twice per month

CPT Code Information

82657

Report Available

30 to 45 days

Reject Due To

Gross hemolysis Reject

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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602)

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

Secondary ID

89656

Testing Algorithm

For information see Congenital Disorders of Glycosylation: Screening Algorithm.