![]() ![]() ![]() The clinical significance of its recognition is that such. ![]() The phenotype is further classified into the regulator and amorph type based on underlying genetic defect. Rh-null patients rarely develop antibodies without stimulation, and most cases occur in response to pregnancy or transfusion (Silvy et al., 2015). Rhnull phenotype is a rare blood group characterized by the lack of expression of all Rh antigens (D, C, c, E and e) on the red cells. Clinically, Rh-null patients present mild to moderate hemolytic anemia cells exhibit characteristic morphologic and functional abnormalities including spherocytosis, stomatocytosis, and diminished lifespan. The RH-null amorph phenotype thus arises from inactivating mutations in RHCE on a D-negative background (summary by Huang et al., 1998 and Huang et al., 2000). The absence of the D antigen, produced by the RHD gene, is common in the human population the D-negative phenotype may result from deletion or genetic alteration of the RHD gene. Routine RBC transfusion protocols consider the RhD-positive or RhD-negative type of the donor and the recipient. Four genes must therefore be silenced to produce the RH-null phenotype. The Rh blood group system is highly immunogenic and is often implicated in hemolytic disease of the newborn and hemolytic transfusion reactions. The RH locus contains the RHD (111680) and RHCE genes tandemly arranged at chromosome 1p36-p34. What is unusual about Rh-Negative blood is that the gene for it is surprisingly common. This is especially true when the recipient’s blood type is unknown or in the case of an emergency when there is no time to test the recipients blood group. This explanation seems to be the one most consistent with available evidence and the one that is most able to withstand Occam’s Razor. O negative blood is special because it is the universal blood type, meaning that it is the preferred choice for blood transfusions. The amorph type arises from mutations at the RH locus itself that silence Rh expression. The majority of scientists who have studied the blood type have concluded that it is most likely just a random mutation. The regulator type is caused by mutation in the RHAG gene (180297). Two RH-null types, the regulator type (RHNR 268150) and the amorph type (RHNA), arising from independent genetic mechanisms have been distinguished. The RH-null phenotype designates rare individuals whose red blood cells lack all Rh antigens. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |