Galactosemia (GALT) Sequencing and Deletion/Duplication
Also known as: GALT NGS
Use
This test is used to detect pathogenic variants in the GALT gene, which is crucial for confirming carrier status or diagnosing galactosemia in individuals with decreased GALT enzyme activity. Galactosemia is a disorder of galactose metabolism due to GALT deficiency, leading to potential life-threatening conditions such as classic galactosemia and clinical variant galactosemia. These can cause symptoms like diarrhea, hepatocellular damage, and sepsis. A lactose-restricted diet initiated early can prevent neonatal complications, though long-term issues may still arise in certain cases. Benign variant galactosemia, like the Duarte variant, does not usually require dietary restrictions. This test aids in deciding appropriate management and genetic consultation recommendations.
Special Instructions
The test should be ordered with a Galactosemia Testing Patient History Form and informed consent for genetic testing, especially for New York State patients. New York clients should note that specimens will be sent to a state-approved laboratory if required. The preferred initial test for diagnosis or carrier assessment is the Galactosemia (GALT) Enzyme Activity and 9 Mutations test.
Limitations
A negative result does not exclude the diagnosis of galactosemia. The test detects variants within coding regions and intron-exon boundaries of the GALT gene. It might not detect some deletions, duplications, or insertions by massively parallel sequencing. Regulatory and deep intronic variants are not identified, and diagnostic errors can occur due to rare sequence variations. Some variants may not be detected due to technical limitations like pseudogenes or repetitive regions. This test is not designed to detect low-level mosaic, somatic variants, or some complex genomic events. Results could be affected if the patient has had an allogeneic stem cell transplant.
Methodology
NGS (Targeted)
Biomarkers
Result Turnaround Time
10-15 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 mL
Minimum Volume
2 mL
Container
Lavender or pink (EDTA) or yellow (ACD solution A or B). New York State Clients: Lavender (EDTA)
Storage Instructions
Refrigerated
Causes for Rejection
Serum or plasma; grossly hemolyzed or frozen specimens; saliva, buccal brush, or swab; FFPE tissue.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 2 weeks |
| Frozen | Unacceptable |
Other tests from different labs that may be relevant