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Test Code LAB1849 Galactosemia DNA Analysis

Clinical System Name

Galactosemia (GALT) DNA Analysis

Synonyms

Galactosemia DNA (8 mutations)

Galactosemia Common Mutation Panel

Galactosemia Known Mutation Analysis

 

Description

Galactosemia affects about 1/10,000 individuals and is included in the Washington State newborn screening program.  The Seattle Children's Hospital Molecular Laboratory offers two different options for GALT DNA Analysis:

Common Mutation Panel: Analysis of the GALT gene for the following 8 common mutations: p.S135L (c.404 C>T), p.F171S (c.512 T>C), p.Q188R (c. 563 A>G), p.L195P (c.625 A>G), p.Y209C (c. 625 A>G), p.K285N (c.855 G>T), p. N314D (c. 940 A>G) (Duarte variant), p. L218L (c.1721 C>T) (LA variant)

Targeted Variant Analysis - For targeted analysis of variants previously identified through clinical testing of a family member or research testing of the individual.  Please provide copies of proband reports when requesting targeted variant analysis for cases NOT performed by Seattle Children's Lab.

Sample Requirements

Note: For patients who have had a whole blood transfusion, wait 10 days post transfusion to draw for genetic testing. No wait time is necessary for blood or saliva collection if the patient received leuko-reduced red cells or plasma.

 

Specimen: Whole blood, cord blood

Container(s): Lavender/EDTA, Yellow/ACD A or B

Preferred Vol: 3 mL

Minimum Vol: 1 mL

 

Note: Heparin samples (Green tops) are unacceptable.

 

Specimen: Extracted DNA from EDTA blood

Minimum:　10µg

Note:　Isolation of nucleic acids for clinical testing must be performed in a CLIA-certified

laboratory or a laboratory meeting equivalent requirements as determined by the CAP

and/or the CMS.　DNA concentration minimum 50 µg/mL; 260/280 ratio 1.70-2.00.

  

Specimen: Cultured cells

Acceptable:  Fibroblasts

Container(s): T-25 flasks

Preferred Vol: 2 flasks

Processing Instructions

Reject due to: Heparin

Spin: No

Aliquot: No

Temp: Refrigerate

Storage location: Molecular Genetics box in CPA refrigerator #2

 

Off-site collection: Refrigerate blood samples until ready to ship.  Transport all sample types at room temperature via overnight shipping.

Stability

Specimen Type Temperature Time
Cultured cells Room temp 3 days
Whole blood, extracted DNA Room temp 3-5 days
Whole blood, extracted DNA Refrigerated 7 days
Extracted DNA Frozen ok

 

Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.

Availability

STAT Performed TAT
Contact lab Monday - Friday 2-3 weeks

 

Performing Laboratory

Seattle Children's Laboratory

Department

Department:  Molecular Genetics Laboratory

Phone: 206-987-3872

 

Lab Client Services: 206-987-2617

 

Lab Genetic Counselor: LabGC@seattlechildrens.org

CPT Codes

GALT 8 Mutation Panel    81401
GALT Targeted Variant Analysis 81403

 

Methodology

Method: PCR + Sequencing

 

Limitations: This test is for the specified targeted 8 variants analysis only.

Reference Range

Interpretive report will be provided

Requisition

Molecular Genetics

Special Instructions

Links to: Galactosemia GeneReview

Clinical Utility

Galactosemia is an inherited disorder of galactose metabolism. Individuals with galactosemia are unable to break down galactose, a sugar found primarily in dairy products and some vegetables and legumes. Galactosemia is caused by a deficiency in the enzyme galactose-1-phosphate uridyltransferase, and individuals with galactosemia have mutations in the GALT gene. They also have elevated galactose-1-phosphate, a metabolite of galactose metabolism. Galactosemia affects about 1/10,000 individuals and is included in the Washington State newborn screening program.