Ordering Recommendation
Molecular (DNA) test to identify the causative mutations when GALT enzyme activity is known. To diagnose or rule out galactosemia, refer to Galactosemia (GALT) Enzyme Activity and 9 Mutations (0051175).
Mnemonic
Methodology
Polymerase Chain Reaction/Single Nucleotide Extensions
Performed
Mon, Wed, Fri
Reported
7-10 days
New York DOH Approval Status
Specimen Required
Lavender (EDTA), pink (K2EDTA), or green (sodium heparin).
Transport 3 mL whole blood. (Min: 1 mL)
Refrigerated.
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval
By report
Interpretive Data
Interpretive Data:
Background Information for Galactosemia (GALT) 9 Mutations:
Characteristics: Affected infants present at 3-14 days old with poor feeding, vomiting, diarrhea, jaundice, lethargy progressing to coma, and abdominal distension with hepatomegaly usually followed by progressive liver failure. Patients with galactosemia are also at increased risk for E. coli or other gram-negative neonatal sepsis. Diagnosis is made by measuring GALT enzyme activity in red blood cells.
Incidence: Approximately 1 in 30,000 to 60,000 of classic galactosemia in Caucasian, varies in other populations.
Inheritance: Autosomal recessive.
Penetrance: 100 percent for severe GALT mutations.
Cause: Mutations in the GALT gene.
Mutations Tested: Seven GALT gene mutations (Q188R, S135L, K285N, T138M, L195P, Y209C, and IVS2-2 A>G) and two variants (N314D and L218L).
Clinical Sensitivity: Approaches 80 percent in Caucasians but reduced in other ethnic groups.
Methodology: Polymerase chain reaction followed by single nucleotide extension (SNE) and capillary electrophoresis.
Analytical Sensitivity: 99 percent for mutations listed.
Limitations: GALT gene mutations, other than the 9 targeted, will not be detected. Diagnostic errors can occur due to rare sequence variations.
This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
Laboratory Developed Test (LDT)
Note
This test is offered to individuals with known familial mutation(s).
Hotline History
CPT Codes
81401
Components
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
0051177 | Galactosemia - Ethnicity | 42784-9 |
0051178 | Galactosemia - Symptoms | |
0051180 | Galactosemia - Family History | 8670-2 |
0051182 | Galactosemia (GALT) Allele 1 | 42940-7 |
0051183 | Galactosemia (GALT) Allele 2 | 42941-5 |
0051184 | Galactosemia (GALT) DNA Panel Interp | 50398-7 |
2001351 | Galactosemia (GALT) DNA Panel Specimen | 66746-9 |
Aliases
- Galactosemia Carrier Testing
- Galactosemia Confirmation Test
- Galactosemia genotyping
- GALT DNA