Miscellaneous Blood Group Systems

• The Diego System includes 22 antigens, the main ones being

  • Dia/Dib
  • Wra/Wrb
• Dia and Wra are low-incidence antigens
• Dia is very rare except in Asians - it serves as a marker in anthropological studies of Mongolian ancestry; also is increased in indigenous people of North and South American
• Dib and Wrb are high-incidence antigens
• Dia and Dib antibodies

  • usually IgG
• Dia and Dib antibodies

  • generally require antiglobulin test for detection
• Dia and Dib antibodies

  • anti-Dia occasionally binds complement and lyses red cells
• Dia and Dib antibodies

  • anti-Dia can cause severe HDFN while anti-Dib has very rarely been implicated in HDFN
• Dia and Dib antibodies

  • anti-Dia and anti-Dib have rarely caused delayed hemolytic transfusion reactions (DHTR)
• Dia and Dib antibodies

  • antigens of the Diego system are not destroyed by proteolytic enzymes such as papin, ficin, or trypsin
• Wr antibodies

  anti-Wra

  • is relatively common and usually detected by AHG
• anti-Wra are mostly IgG but can sometimes be IgM or IgM plus IgG
• Anti-Wra has been responsible for severe HDFN and HTRs
• anti-Wrb

  • alloanti-Wrb is rare, and little is known about its clinical significance
• autanti-Wrb is a relatively common antibody, and it may be implicated in AIHA
• The Yt System

  • Yta and Ytb are antithetical antigens
• Yta is of relatively high prevalence in all populations -- 99.8%
• Ytb is infrequent except in Israeli Jews, Israeli Arabs, and Israeli Druze - 26%
• Yta and Ytb are both destroyed by ficin, papin, and a-chymotrypsin, but are not affected by trypsin
• Yt antibodies

  • anti-Yta and anti-Ytb
• Yt antibodies are stimulated by pregnancy or transfusion
• Yt antibodies are usually IgG
• Yt antibodies require IAT for detection
• anti-Yta has been implicated in acute and delayed HTRs, seem to be immunogenic
• anti-Ytb is poorly immunogenic, and the antibody is rare
• neither anti-Yta or anti-Ytb cause HDFN
• The Xg system

  • two antigens - Xga and CD99 (Xgb) that are controlled by the Xg gene
• Xg is found on the X chromosome, and CD99 is found on both the X and Y chromosome
• Xga has a prevalence of 66% in males and 89% in females
• The Xg system

  sometimes there is a null form: Xg
• null form of Xg system

  • for example, can be Xg Xg
• Xg antibodies

  • Xga antibodies occasionally agglutinate red cells directly (IS) bu are generally IgG and react at IAT
• Xg antibodies

  • anti-Xga antibodies are not clinically significant
• Xg antibodies

  • antigens can be destroyed by proteolytic enzyes
• The Dombrock system

  • Doa and Dob are polymorphic antithetical antigens
  • poor immunogens
• Do(a+b+) is found in about 50% of the population
• Dombrock antibodies

  • aren't common
  • IgG and found at IAT phase
• anti-Doa and anti-Dob have been responsible for acute and delayed HTRs
• Dombrock antibodies do not cause HDFN because the antigens are poorly developed on fetal cells; however, some neonates have been born with a positive DAT result
• Dombrock antibodies

  • antibodies are usually found in people with other alloantibodies, so screening for compatible donors is best done by molecular genotyping