Ordering Recommendation

Initial test to diagnose or rule out classic galactosemia. Recommended carrier testing for galactosemia.

Mnemonic
GALTPAN
Methodology

Enzymatic/Polymerase Chain Reaction/Single Nucleotide Extensions

Performed

Mon, Wed, Fri

Reported

7-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or green (sodium heparin).

Specimen Preparation

Do not freeze. Transport 10 mL whole blood. (Min: 3 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Frozen or room temperature specimens.

Remarks
Stability

Ambient: Unacceptable; Refrigerated: 5 days; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

One U/g Hb is equivalent to one umol/hour/gram of hemoglobin (umol/hr/g Hb).

Background Information for Galactosemia (GALT) Enzyme Activity and 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 DNA: Approaches 80 percent in Caucasians but reduced in other ethnic groups.
Methodology DNA: Polymerase chain reaction followed by single nucleotide extension (SNE) and capillary electrophoresis.
Analytical Sensitivity DNA: 99 percent for mutations listed.
Limitations DNA: GALT gene mutations, other than the 9 targeted, will not be detected. Diagnostic errors can occur due to rare sequence variations.
Methodology Enzymatic: Spectrophotometric quantitation of enzyme activity in red blood cells.

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

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

82775; 81401

Components
Component Test Code* Component Chart Name LOINC
0051171 Galactosemia (GALT) DNA Pan,G1PUT Spec
0051177 Galactosemia - Ethnicity 42784-9
0051178 Galactosemia - Symptoms
0051179 Galactosemia - Abnormal Newborn Screen
0051180 Galactosemia - Family History 8670-2
0051182 Galactosemia (GALT) Allele 1 42940-7
0051183 Galactosemia (GALT) Allele 2 42941-5
0051187 Galactosemia (GALT) DNA Pan,G1PUT Interp
0080125 Galac-1-Phos Uridyltransferase 24082-0
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • GALT DNA
  • Galactosemia Carrier Testing
  • Galactosemia Confirmation Test
  • Galactosemia genotyping
Galactosemia (GALT) Enzyme Activity and 9 Mutations