Describe Rh blood group system

Describe Rh blood group system
Ans: ABO blood type is further differentiated by + or- sign.
This positive or negative sign refers to the presence or absence
 of another blood group system antigen called Rh factor.
 Rh blood group system is defined on the basis of Rh
factor present on the surface of RBC.
This system is named Rh after Rhesus monkey.
 because its antigen was first discovered by Landstener in 1930s.
 Rh blood group system is encoded by three genes C, D and E, which
occupy two lightly linked loci. Alleles of gene D occupy one locus called locus
 D, while genes C and E alrematively occupy the other locus. The D locus is
of prime importance.

 Gene D has two alleles, D and d. D is completely dominant over d
. Persons having genotype DD or Dd have Rh factor on their RBC and are
 Rh+. Persons with genotype dd do not have Rh factor and are Rh-.
 Unlike the naturally occurring anti A and anti B antibodies of ABO
system, anti Rh antibody production requires a stimulus by the human
 Rh antigen itself. An Rh- person does not produce anti Rh antibodies
 unless h+ is exposed to Rh- recipient. If an Rh- person receives Rh
 antigen through wrong Rh+ blood transfusion, he will begin to produce
 anti Rh antibodies against Rh antigens. Rh- blood, clear of any anti Rh
 antibody from a donor who has never been exposed to Rh antigen can
 be transferred to Rh+ recipient.