ARUP's Laboratory Test Directory

0051270: Galactosemia, GALT Gene Mutations, Fetal

[ image for: Patient History for Fetal Molecular Testing]
Patient History for Fetal Molecular Testing
  

Test Mnemonic: GALTDNA FE
Methodology: Polymerase Chain Reaction/Single Nucleotide Extensions

Performed: Sun-Sat

Reported: 5-7 days

Specimen Required:  
Collect: and Transport: Cultured cells: Two T-25 flasks at 80% confluent of cultured amniocytes.  Fill flasks with culture media to ship at 20-25°C.  Backup cultures must be retained at the client's institution until testing is complete. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787.
Maternal sample: One 5 mL lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B)
at 20-25°C.

Remarks: Fetal samples are CRITICAL AMBIENT and must be received within 48 hours of shipment due to lability of cells.
Maternal sample is recommended for proper test interpretation.  Maternal Cell (MCC MAT) to be ordered separately (0050608). 

Unacceptable Conditions: Frozen samples.

Stability: Fetal: Ambient: 2 days; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal: Ambient: 24 hours; Refrigerated: 5 days; Frozen: Unacceptable

Reference Interval:
By report

Interpretive Data:
Background Information:
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 1:120 in Caucasians; less common in other ethnic groups.
Inheritance: Autosomal recessive
Penetrance: 100% for severe GALT mutations.
Cause: Mutations in the GALT gene.
Mutations Detected: 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% in Caucasians but reduced in other ethnic groups.
Methodology: Polymerase chain reaction followed by single nucleotide extension (SNE) and capillary electrophoresis.
Analytical Sensitivity: 99% for mutations listed.
Limitations: Other mutations will not be detected.
For quality assurance purposes, ARUP Laboratories will provide a confirmation of the above result at no charge. Following delivery, please collect a cord blood sample from the infant in a lavender (EDTA) or yellow (ACD Solution A) top tube. Please specify on the test request form that it is a confirmatory study to be performed at no charge. Please provide the mother's name for specimen identification purposes.

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.

Please refer to Statement C in the Compliance Statements section in the front of the Laboratory Test Directory.



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

CPT Code(s):
83890 Isolation; 83898 Amplification; 83914 x9 Mutation identification; 83909 Capillary electrophoresis; 83912 Interpretation and report. FCC: 83900 Amplification multiplex (first two sequences); 83901 x14 Amplification; 83909 Capillary electrophoresis. If MCC MAT (0050608) is performed: 83890 Isolation; 83900 Amplification multiplex (first two sequences); 83901 x14  Amplification; 83909 Capillary electrophoresis; 83912 Interpretation and report - Additional CPT code modifiers may be required for procedures performed to test for oncological or inherited disorders.