Rh-hr Genotype With ABO Grouping

Test ID:

705286

CPT code:

86900, 86906

Synonyms:

•Rh Genotype
•Rh-hr Genotype

Clinical Use:

Determine ABO blood grouping and most probable zygosity for D(Rh_o) antigen. Zygosity for C, E, c, and e antigens is also determined. Paternal typing may aid in the prediction of Rh hemolytic disease of the newborn.

Test Information:

Tests for ABO blood grouping and the the Rh antigens D, C, E, c, and e (including test for “weak D,” if applicable) When a woman of childbearing age has anti-D, it is important for prognostic purposes to determine the probability that her husband is homozygous or heterozygous for the gene determining the D antigen. If a prenatal patient is Rh-negative and the father of her fetus is homozygous for D, the child will always be Rh positive. Approximately 50% of the children of a heterozygous father will be Rh-negative. Testing to determine zygosity involves testing the subject’s red blood cells for D, C, E, c, and e antigens. The results of this testing are referred to as the Rh phenotype. The Rh phenotype is used to determine a “most probable” zygosity for D based upon correlation of these results with a frequency chart detailing most probable Rh genotypes. In the case of D, this must be done indirectly since there is no detectable allele for this gene. In the case of the alleles C and c and the alleles E and e, the zygosity of these genes may be directly determined from the phenotyping results. Rh phenotyping of the father may also be helpful for evaluating the potential for hemolytic disease of the newborn in the presence of maternal antibodies to C, c, E, or e antigens.

Specimen Type:

Whole blood

Requested Volume:

4 mL

Minimum Volume:

1 mL

Container Type:

Lavender-top (EDTA) tube

Storage Instructions:

Specimens should be tested as soon as possible or within 72 hours of collection. Samples that cannot be tested immediately should be stored at 2°C to 8°C. Do not freeze red cells.