Ordering Recommendation

Diagnostic testing for galactosemia.

Mnemonic

GALTDNA FE

Methodology

Polymerase Chain Reaction/Single Nucleotide Extensions

Performed

Sun-Sat

Reported

5-7 days; if culture is required, an additional 1 to 2 weeks is required for processing time.

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Fetal: Cultured Amniocytes, Cultured CVS, or Direct Amniotic Fluid (direct) AND Maternal Whole Blood Specimen: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Cultured Amniocytes or Cultured CVS: Transfer cultured amniocytes or cultured CVS to two T-25 flasks at 80 percent confluence. (Min: one T-25 flask at 80 percent confluence). Backup cultures must be retained at the client's institution until testing is complete. If ARUP receives a sample below the minimum confluence, CG GRW&SND (0040182) will be added on by ARUP, and additional charges will apply. If clients are unable to culture specimens, CG GRW&SND should be added to the initial order.
Direct Amniotic Fluid:
10 milliliters
Maternal Whole Blood Specimen:
2 mL whole blood (Min: 1 mL).

Storage/Transport Temperature

Cultured Amniocytes or Cultured CVS: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of collection due to viability of cells.
Direct Amniotic Fluid: Ship room temperature.
Maternal Whole Blood Specimen:
Room temperature

Unacceptable Conditions
Remarks
Stability

Cultured Amniocytes or Cultured CVS: Room temperature: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Direct Amniotic Fluid: Room temperature: 48 hours; Refrigerated: 72 hours; Frozen: Unacceptable
Maternal Whole Blood Specimen: Room temperature: 7 days; Refrigerated: 1 month; 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 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 for classic galactosemia in Caucasians; 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.

Compliance Category

Laboratory Developed Test (LDT)

Note

This test is offered to individuals with a known familial mutation(s).

Hotline History

N/A

CPT Codes

81401; 81265 Fetal Cell Contamination (FCC)

Components

Component Test Code* Component Chart Name LOINC
0050548 Maternal Contamination Study Fetal Spec 59266-7
0050612 Maternal Contam Study, Maternal Spec 66746-9
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
2001352 Galactosemia (GALT) DNA Pan, Fetal Spec 31208-2
* 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

  • Galactosemia Carrier Testing
  • Galactosemia Confirmation Test
  • Galactosemia genotyping
  • GALT DNA
Galactosemia (GALT) 9 Mutations, Fetal