6 Minor Blood Group Systems

• Diego system has 2 sets of independent pairs of antithetical antigens
• Dia (Diego system) serves as a useful tool in anthropogenic studies of Mongolian ancestry. If you have this antigen, you have a Mongolian lineage
• Dia and Dib (Diego system) is located at AE-1, a type of receptor on surface of RBC; anion exchange protein on RBCs
• Mutations in AE-1 are associated with poikilocytosis
• Anti-Dia and Dib (Diego system) are IgG and do not bind C'; it is associated with mild to severe HTR and HDN
• Anti-Dia (Diego system) demonstrates dosage effect
• Wra and Wrb (Diego system) is first classified as an independent blood group system and later as a collection
• Yt System (011), formerly known as Cartwright is located on Acetylcholinesterase

  • Sensitive to reducing agents
  • Antibodies are IgG
  • Associated with transfusion reaction but no reports have associated Yt with HDN
• Xg System (012) is located at the short arm of X chromosome

  • Antigen is sensitive to most enzymes but not to reducing agents; poor immunogenic
• Yta antigen (Yt system) has high incidence, and Ytb has low incidence
• Yta antigen (Yt system) variably sensitive to certain enzymes; not well developed at birth; strongly immunogenic
• Ytb antigen (Yt system) is well developed at birth but poorly immunogenic
• Anti-Xga (Xg system) is IgG and binds C'

  • Associated with HTR and HDN
• Scianna System (013) is composed of Sc1 (high)/ Sc2 (low), Sc3 (High), Radin [Rd] (low)
• Sc1/Sc2 (Scianna system) are resistant to standard enzymes; sensitive to reducing agents
• Anti-Sc1 (Scianna system) is IgG and binds to C'

  • Not implicated with HTR
• Anti-Sc2 (Scianna system) is rare and does not bind to C'

  • Not implemented with HTR
• Anti-Sc2 and anti-Rd (Scianna system) are associated with mild HDN
• Anti-Sc3 (Scianna system) is IgG

  • Associated with HTR but not with HDN
• Dombrock System (014) consists of Doa / Dob , Gregory (Gya ), Holley ( Hy ), Joseph (Joa)

  • Associated with acute/delayed HTR but not with HDN
  • Absence of DO expression is seen in PNH III
• Doa/Dob (Dombrock system) are resistant to ficin and papain, and sensitive to trypsin, pronase and reducing agents
• DO antibodies (Dombrock system) are weakly reactive IgG and does not bind C'

  • Reacts optimally in IAR with PEG or enzyme enhancement
• Colton System (015) is composed of Coa/Cob, and Co3 (formerly Coab)

  • All antigens are resistant to all enzymes and reducing agents
  • Located on Aquaporin-1
  • Antibodies are IgG; associated with acute/delayed HTR
• Coa antigen (Colton system) has high incidence
• Cob antigen (Colton system) is only 10% of random population
• Aquaporin-1 is a primary plasma membrane water channels for the regulation of osmotic water transport
• Anti-Cob (Colton system) weakly binds C’; associated with subclinical to mild HDN
• Co3 (Colton system) has high incidence antigen present on RBCs carrying Coa and/or Cob but not in null phenotype
• Anti-Co3 (Colton system) has potent IgG and binds C’; associated with severe HDN and mild HTR
• Co(a-b-) (Colton system) is linked with monosomy 7 of the bone marrow (associated with myeloid leukemia and preleukemia dysmyelopoietic syndromes)
• Chido/Rodgers System (017) has 9 antigens = 6 Chido Antigens, 2 Rogers Antigens and WH antigen

  • None of the antigens are antithetical
  • Poorly expressed on cord cells, sensitive to treatment with most enzymes and resistant to reducing agents
  • Antibodies are collectively grouped as “high-titer low avidity”
  • Associated with human leukocyte antigen system and complement proteins
• Gerbich System (020) is composed of 3 high incidence antigens (Ge2, Ge3, Ge4) and 4 low incidence antigens (Wb, Lsa , Ana , Dha)

  • Expressed on RBC membrane glycophorin C and/or D
  • Antibodies are generally IgG, RBC stimulated, variably binds C'
• Individuals with the Leach phenotype → GE: -2, -3, -4, (Gerbich system) is associated with elliptocytosis
• Anti-Ge2 & Anti-Ge3 can be IgM; it isnon-RBC stimulated

  • Autoantibodies
  • Associated with acute/delayed HTR but not HDN
• Little is known about the Antibodies against low incidence GE antigens
• Cromer System (021) is composed of 8 high incidence antigens (Cra, Tea, Dra, Esa, IFC, UMC, WESb, GUTI) and 3 low incidence antigens (Tcb, Tcc, and WESa)

  • Most antigens are sensitive to chymotrypsin and pronase
  • Reducing agents have little effect
  • Antigens are carried by DAF (CD55)
  • Antibodies are generally IgG1
  • Antibodies are rarely observed
• Inab (Cromer system) is a null phenotype; it lacks DAF
• Knops System (022) is composed of 8 antigens: Kna/Knb, Sl11 (Swain-Langley)/Sl2 (Vil), McCa/McCb, Yka, and Sl3

  • Antigens are resistant to ficin and papain, weakened/destroyed by trypsin, chymotrypsin and reducing agent
  • Poorly expressed on cord cells and depressed in patients with autoimmune disease
  • Antigens are carried in CR1
  • Antibodies are IgG, RBC stimulated, weakly/variably reacts at IAR phase
  • Clinically insignificant (no reports of HTR/HDN)
• Indian System (023) by Badakere et al in 1973, composed of 2 antigens: Ina/Inb

  • Antigens are susceptible to most enzymes and reducing agents
  • Poorly expressed on cord cells
  • Antigens are carried on CD44
  • Antigens are immunogenic
  • Antibodies are IgG, RBC-stimulated, reactive at IAR phase; not associated with HDN
• Anti-Inb (Indian system) has few HTR cases reported