Test ID: PMMIF
Phosphomannomutase (PMM) and Phosphomannose Isomerase (PMI), Fibroblasts
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosis of congenital disorders of glycosylation Ia (phosphomannomutase-2 deficiency [CDG-Ia or PMM2-CDG]) and Ib (phosphomannose isomerase deficiency [CDG-Ib or MPI-CDG]) as measured in fibroblasts
A follow-up test for patients with an abnormal transferrin isoform profile as determined by isoelectric focusing or liquid chromatography-mass spectrometry (eg, CDG/89891 Carbohydrate Deficient Transferrin for Congenital Disorders of Glycosylation, Serum)
Additional Tests Lists test(s) that are always performed, at an additional charge, with the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FIBR | Fibroblast Culture | Yes | Yes |
| CRYOB | Cryopreserve for Biochem Studies | No | Yes |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, a fibroblast culture and cryopreservation for biochemical studies will always be performed at an additional charge. However, for multiple lysosomal enzyme assays on a patient utilizing fibroblast culture, only 1 culture is required regardless of the number of enzyme assays ordered. If viable cells are not obtained within 10 days, client will be notified.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
PMMIF/89657: Colorimetric Enzyme Assay
FIBR/8482: Cultivated from Biopsy as Monolayer
CRYOB/88832: Fibroblast Subculture Followed by Cryopreservation and Storage
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
CDG (Congenital Disorders of Glycosylation)Type II
CDG-Ia
CDG-Ib
Congenital Disorders of Glycosylation (CDG)Type I
Congenital Disorders of Glycosylation (CDG)Type II
Phosphomannose Isomerase (PMI)
PMI (Phosphomannose Isomerase)
PMM (Phosphomannomutase)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
This test is not recommended for prenatal testing.
Forms:
1. 1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
2. 2. If not ordering electronically, submit a Biochemical Genetics Request Form (Supply T439) with the specimen.
Submit only 1 of the following specimens:
Specimen Type: Cultured fibroblasts
Container/Tube: T-75 or T-25 flask
Specimen Volume: 1 Full T-75 flask or 2 full T-25 flasks
Specimen Stability Information: Ambient (preferred)/Refrigerated 24 hours
Specimen Type: Skin biopsy
Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin. Tubes can be supplied upon request (Eagle's minimum essential medium with 1% penicillin and streptomycin [Supply T115]).
Specimen Volume: 4-mm punch
Specimen Stability Information: Refrigerated (preferred)/Ambient
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Specimen in formalin or fixative preservative |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Tissue | Varies | |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Congenital disorders of glycosylation (CDG), formerly known as carbohydrate-deficient glycoprotein syndrome, are a group of inherited metabolic diseases that affect 1 of the steps of the pathway involved in glycosylation. CDGs typically present as multisystemic disorders with developmental delay, hypotonia, abnormal magnetic resonance imaging (MRI) findings, hypoglycemia, and protein-losing enteropathy. There is considerable variation in the severity of this group of diseases, which can range from hydrops fetalis to a mild presentation in adults. In some subtypes (Ib, in particular) intelligence is not compromised.
Phosphomannomutase-2 deficiency (CDG-Ia or PMM2-CDG) is an autosomal recessive glycosylation disorder resulting from reduced or absent activity of the enzyme phosphomannomutase-2, encoded by the PMM2 gene. Over 700 individuals have been described to date, making it the most common congenital disorder CDG worldwide. All patients with CDG-Ia have a neurological manifestation of disease with variable involvement of other organ systems. Individuals with this disorder typically present in the neonatal period with failure to thrive, developmental delay, abnormal subcutaneous fat distribution, elevated liver transaminases, and abnormal MRI findings. Currently, there is no cure and treatment remains primarily supportive and symptomatic.
Phosphomannose isomerase deficiency (CDG-Ib or MPI-CDG) is an autosomal recessive glycosylation disorder resulting from reduced or absent activity of phosphomannose isomerase, an enzyme encoded by the MPI gene. This subtype of CDG is unique in that there is little to no involvement of the central nervous system. The primary clinical manifestations are a result of aberrant gastrointestinal function. In particular, individuals with CDG-Ib may present with failure to thrive, hypoglycemia, chronic diarrhea, and protein-losing enteropathy. Although CDG-Ib can be life threatening, it can be effectively treated with mannose supplementation.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
PMM
Normal >700 nmol/h/mg Prot
PMI
Normal >1,500 nmol/h/mg Prot
Interpretation Provides information to assist in interpretation of the test results
Normal results are not consistent with either phosphomannomutase-2 deficiency (CDG-Ia or PMM2-CDG) or phosphomannose isomerase deficiency (CDG-Ib or MPI-CDG).
Markedly reduced activity of phosphomannomutase is consistent with a diagnosis of CDG-Ia. Markedly reduced activity of phosphomannose isomerase is consistent with a diagnosis of CDG-Ib.
Mild to moderately reduced enzyme activities will be interpreted in the context of clinical and other laboratory test information submitted with the specimen.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not appropriate for carrier testing.
The initial screening test for congenital disorders of glycosylation is transferrin isoform analysis (CDG/89891 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.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Jaeken J: Congenital Disorders of Glycosylation. Ann N Y Acad Sci 2010;1214:190-198
2. Jaeken J, Matthijs: Congenital Disorders of Glycosylation: A Rapidly Expanding Disease Family. Annu Rev Genomics Hum Genet 2007;8:261-278
3. Marquardt T, Denecke J: Congenital disorders of glycosylation: review of their molecular bases, clinical presentations and specific therapies. Eur J Pediatr 2003 Jun;162(6):359-379
Method Description Describes how the test is performed and provides a method-specific reference
One confluent T75 flask of fibroblasts is harvested and the cell pellet is subjected to 1 freeze-thaw cycle. The lysate is collected and the enzymatic activity for both phosphomannomutase and phosphomannose isomerase is measured by a colorimetric assay (Dr. Otto van Diggelen, Erasmus University, Rotterdam, The Netherlands; personal communication).
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Tuesday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82657-PMM and PMI
88233-Fibroblast culture
88240-Cryropreservation for biochemical studies
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 50824 | Specimen | 31208-2 |
| 50825 | Specimen ID | N/A |
| 50826 | Source | N/A |
| 50827 | Order Date | N/A |
| 50828 | Reason For Referral | 42349-1 |
| 50829 | Method | In Process |
| 50830 | Phosphomannomutase, Fibro | In Process |
| 50831 | Phosphomannose Isomerase, Fibro | In Process |
| 50832 | Interpretation | 59462-2 |
| 50833 | Amendment | In Process |
| 50834 | Reviewed By | N/A |
| 50835 | Release Date | N/A |
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