Ordering Recommendation

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




Enzymatic Assay/Polymerase Chain Reaction/Single Nucleotide Extensions


Mon, Wed, Fri


7-10 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

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

Specimen Preparation

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

Storage/Transport Temperature


Unacceptable Conditions

Frozen or room temperature specimens.


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:
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.

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.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes

82775; 81401


Component Test Code* Component Chart Name LOINC
0051171 Galactosemia (GALT) DNA Pan,G1PUT Spec 31208-2
0051177 Galactosemia - Ethnicity 42784-9
0051178 Galactosemia - Symptoms
0051179 Galactosemia - Abnormal Newborn Screen 46737-3
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 62365-2
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.


  • Galactosemia Carrier Testing
  • Galactosemia Confirmation Test
  • Galactosemia genotyping
Galactosemia (GALT) Enzyme Activity and 9 Mutations