Assess risk for alloimmune hemolytic disease of the newborn or hemolytic transfusion reaction. May be ordered for parental or fetal genotyping.
- Patient Preparation
- 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 Remarks): Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). Parental Genotyping: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- 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
- Maternal specimen is recommended for proper test interpretation if contamination of the fetal specimen from the mother is suspected. Order Maternal Cell Contamination. Patient History Form is available on the ARUP website or by contacting ARUP Client Services.
- Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Whole Blood or Maternal Cell contamination Specimen: Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Fetal or neonatal hemolytic anemia, erythroblastosis and hydrops.
K Allele Frequency: 9 percent of Caucasians, 2 percent of African Americans; unknown for other ethnic groups.
Inheritance: Autosomal dominant.
Cause: Maternal-fetal or transfusion-related K antigen incompatibility.
Polymorphism Tested: KEL1 and KEL2 alleles of the KEL gene. The KEL1 allele is known as K (c.578C>T; p.Thr193Met) and the KEL2 allele is known as k (common allele). The presence of the KEL1 allele predicts a Kell-positive phenotype.
Clinical Sensitivity: 99 percent.
Methodology: Polymerase chain reaction (PCR) and fluorescent monitoring using hybridization probes to detect the c.578C>T polymorphism.
Analytic Sensitivity and Specificity: 99 percent.
Limitations: Bloody amniotic fluid samples may give false-negative results because of maternal cell contamination. Diagnostic errors can occur due to rare sequence variations.
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0051646||Kell K/k Antigen (KEL) Genotyping|
- KEL 1 and 2 genotyping
- Kel1 heterzygosity or homozygosity assay
- Kell Antigen genotyping