Ordering Recommendation

Assess risk for alloimmune hemolytic disease of the fetus and newborn (HDFN) or hemolytic transfusion reaction. May be ordered for parental or fetal genotyping.

Mnemonic
RHE GENO
Methodology

Polymerase Chain Reaction/Fluorescence Monitoring

Performed

Varies

Reported

3-10 days

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

Fetal Genotyping: Amniotic fluid OR two T-25 flasks at 80 percent confluency of cultured amniocytes. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787.
WITH Maternal Cell Contamination Specimen (see Note): Lavender (K2EDTA), Pink (K2EDTA), or Yellow (ACD Solution A or B).
Parental Genotyping:
Lavender (K2EDTA), Pink (K2EDTA).

Specimen Preparation

Amniotic Fluid: Transport 10 mL unspun fluid. (Min: 5 mL)
Cultured Amniocytes:
Fill flasks with culture media. Transport two T-25 flasks at 80 percent confluency of cultured amniocytes filled with culture media. Backup cultures must be retained the client's institution until testing is complete.
Maternal Cell Contamination Specimen:
Transport 3 mL whole blood (Min: 1 mL)
Whole Blood (Parental Genotyping):
Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Amniotic fluid: Room temperature.
Cultured Amniocytes: CRITICAL ROOM TEMPERATURE.
Must be received within 48 hours of shipment due to liability of cells.
Whole Blood or Maternal Cell Contamination Specimen:
Refrigerated.

Unacceptable Conditions

Plasma or serum. Specimens collected in sodium heparin tubes.

Remarks

Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services.

Stability

Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Whole Blood or Maternal Cell Contamination Specimen:
Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

By report

Interpretive Data

Background Information for RhE/e (RHCE) Antigen Genotyping
Characteristics:
Erythrocyte alloimmunization may result in hemolytic transfusion reactions or hemolytic disease of the fetus and newborn (HDFN).
E Antigen Frequency: 0.29 Caucasians, 0.22 African Americans, 0.39 Asians.
e Antigen Frequency: 0.98 Caucasians, 0.98 African Americans, 0.96 Asians.
Inheritance: Co-dominant.
Cause:
Antigen-antibody mediated red-cell hemolysis between donor/recipient or transferred maternal antibodies.
Polymorphism Tested: Rh blood group RHCE*3 (E), RHCE*5 (e): c.676G>C; p.Ala226Pro.
Clinical Sensitivity: 99 percent.
Methodology:
Immucor PreciseType™ HEA Molecular BeadChip which is FDA-approved for clinical testing.
Analytic Sensitivity and Specificity: 99 percent.
Limitations:
Bloody amniotic fluid samples may give false-negative results because of maternal cell contamination. Rare nucleotide changes leading to altered or partial antigen expression and null phenotypes are not detected by this assay. This assay is occasionally limited in predicting genotype due to extreme variation in the Rh locus. False-negative Rhe predictions may result due to RHCE-D-CE fusion genes. Patients who have had hematopoietic stem cell transplants may have inconclusive results on this test. Abnormal signal intensities may result in indeterminate genotyping results.

For quality assurance purposes, ARUP Laboratories will confirm the above result at no charge following delivery. Order Confirmation of Fetal Testing and include a copy of the original fetal report (or the mother's name and date of birth) with the test submission. Please contact an ARUP genetic counselor at (800) 242-2787 extension 2141 prior to specimen submission.

Compliance Category

FDA

Note

Maternal specimen is recommended for proper test interpretation if contamination of the fetal specimen from the mother is suspected. Order Maternal Cell Contamination.

Hotline History
N/A
CPT Codes

0001U

Components
Component Test Code* Component Chart Name LOINC
3002019 RHE GENO Specimen 31208-2
3002020 RhEe Genotype 48030-1
* 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
  • RHCE genotyping
RhE/e (RHCE) Antigen Genotyping