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).
Polymerase Chain Reaction/Single Nucleotide Extensions
Mon, Wed, Fri
Lavender (EDTA), pink (K2EDTA), or green (sodium heparin).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
Laboratory Developed Test (LDT)
This test is offered to individuals with known familial mutation(s).
|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|
- Galactosemia Carrier Testing
- Galactosemia Confirmation Test
- Galactosemia genotyping
- GALT DNA