Molecular (DNA) test to identify the causative mutations for galactosemia when GALT enzyme activity is consistent with galactosemia and the 9 mutation panel does not identify two causative mutations. To diagnose or rule out galactosemia, refer to Galactosemia (GALT) Enzyme Activity and 9 Mutations (0051175).
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Vomiting, diarrhea, feeding problems, failure to thrive, hepatocellular damage, bleeding, sepsis, mental retardation, and neonatal death. If treated early, most symptoms resolve, although speech, motor problems, developmental delay and premature ovarian failure may persist.
Incidence: Approximately 1 in 30,000.
Inheritance: Autosomal recessive
Penetrance: 100 percent for severe mutations.
Cause: Pathogenic galactose-1-phosphate uridyl transferase (GALT) gene mutations.
Clinical sensitivity: 98 percent.
Methodology: Bidirectional sequencing of the entire GALT coding region, intron/exon boundaries and partial 5'UTR.
Analytic Sensitivity & Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations, and large deletions/duplications will not be detected. Mutations in genes other than GALT are not evaluated.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2006698||Galactosemia (GALT) Sequencing Specimen|
|2006699||Galactosemia (GALT) Sequencing Interp|
- Galactosemia Carrier Testing
- Galactosemia Confirmation Test
- Galactosemia genotyping
- GALT DNA sequencing