Kell K/k Antigen (KEL) Genotyping
Ordering Recommendation

Assess risk for alloimmune hemolytic disease of the newborn or hemolytic transfusion reaction. May be ordered for parental or fetal genotyping.

Polymerase Chain Reaction/Fluorescence Monitoring
Mon, Thu
2-7 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
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 
Reference Interval
Interpretive Data
Background information: Kell K/k Antigen (KEL) Genotyping:
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.

Statement C: Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
Component Test Code*Component Chart NameLOINC
0051645KEL Specimen
0051646Kell K/k Antigen (KEL) Genotyping
* 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 view this test within the Laboratory Test Directory found at
  • KEL 1 and 2 genotyping
  • Kel1 heterzygosity or homozygosity assay
  • Kell Antigen genotyping