ARUP's Laboratory Test Directory

Galactosemia, (GALT) 9 Mutations : 0051176
[ image for: Patient History For Galactosemia]
Patient History For Galactosemia
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Additional Technical Information


Mnemonic: GALTDNA

Ordering Recommendation: Diagnostic testing for galactosemia or carrier screening for galactosemia.
Methodology: Polymerase Chain Reaction/Single Nucleotide Extensions
Performed: Tue, Thu
Reported: 7-10 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA), or green (sodium heparin).

Specimen Preparation: Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval:
By report
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 Gramnegative 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:
Other mutations will not be detected.

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Note: This test is offered to individuals with known familial mutation(s).
CPT Code(s): 81401