Clinical Significance of Rhnull and Rhmod

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Clinical Significance of Rhnull and Rhmod

Individuals with Rhnull syndrome demonstrate mild compensated hemolytic anemia, stomatocytosis, reticulocytosis, increase in hemoglobin F, slight to moderate decrease in hemoglobin and hematocrit, decrease in haptoglobin, and possibly elevated bilirubin. This syndrome is highly variable among these individuals, even within the same family. Whenever transfusion is necessary, only Rhnull blood can be given. In addition to the compensated anemia, there is alteration of other blood group antigens in these individuals. They are negative for the high prevalence antigen LW and for FY5, an antigen in the Duffy blood group system. Expression of the S, s, and U antigens found on glycophorin B may also be depressed.
Individuals of the Rhmod phenotype have altered RhAG protein caused by mutations in the RHAG gene, resulting in weakened expression of the Rh and LW antigens. Like Rhnull, S, s, and U antigen expression may be depressed. These individuals exhibit features of the Rhnull syndrome, with less severe clinical symptoms that are rarely remarkable.

Harmening, DM,: Modern Blood Banking & Transfusion Practices, 6th ed. FA Davis, Philadelphia, PA, 2012, p 163.
Howard, PR, Basic & Applied Concepts of Blood Banking and Transfusion Practices, 4th ed, Elsevier, St. Louis, MO, 2017, p 137.