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Test Code GALTP Galactose-1-Phosphate Uridyltransferase Biochemical Phenotyping, Erythrocytes

Reporting Name

Gal-1-Phos Urdyltrns Phenotype,RBC

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Determining the biochemical phenotype for galactosemia when enzymatic and molecular results are incongruent

Method Name

Isoelectric Focusing


Ordering Guidance


The preferred test to evaluate for possible diagnosis of galactosemia, routine carrier screening, and follow-up of abnormal newborn screening results is GCT / Galactosemia Reflex, Blood.

 

For monitoring of dietary compliance, order GAL1P / Galactose-1-Phosphate, Erythrocytes.



Necessary Information


Patient's age is required.

 

A quantitative galactose-1-phosphate uridyltransferase level (GALT / Galactose-1-Phosphate Uridyltransferase, Blood) is required for accurate interpretation.

 

Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.



Specimen Required


Multiple whole blood tests for galactosemia can be performed on 1 specimen. Prioritize order of testing when submitting specimens. For a list of tests that can be ordered together see Galactosemia-Related Test List.

 

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL


Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated (preferred) 28 days
  Ambient  14 days

Reject Due To

Gross hemolysis Reject

Reference Values

An interpretative report will be provided.

Interpretation

Different banding patterns obtained by isoelectric focusing of galactose-1-phosphate uridyltransferase (GALT) can be consistent with classic galactosemia, carrier status for a disease-causing GALT variant, compound heterozygosity, or a normal biochemical phenotype. The banding pattern is interpretated in the context of the separately measured GALT activity.

Day(s) Performed

Pre-analytical processing: Monday through Saturday

Assay performed: Twice per month, Thursday

Report Available

4 to 17 days

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.

CPT Code Information

82664

82775

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GALTP Gal-1-Phos Urdyltrns Phenotype,RBC 33780-8

 

Result ID Test Result Name Result LOINC Value
80341 Gal-1-Phos Urdyltrns Phenotype,RBC 33780-8
34524 Reviewed By 18771-6

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) is recommended.

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

Additional Tests

Test ID Reporting Name Available Separately Always Performed
GALT Gal-1-P Uridyltransferase, RBC Yes Yes

Testing Algorithm

A quantitative galactose-1-phosphate uridyltransferase (GALT) level is used in addition to the isoelectric focusing for accurate interpretation. If recent GALT test results are not provided, GALT testing will be automatically performed at an additional charge. However, if previous GALT results are provided, GALT testing will be canceled.

 

For more information see Galactosemia Testing Algorithm.