Usual Suspects Danny Deck

Whioch chromosome is the ABO system located on?

Chromosome 9

Where are the Rh genes found

Chromosome 1

Which chromsome encodes the duffy (FY) system?

Chromosome 1

Same as Rh

What chromosome is the Kidd (JK) system located on?

Chromosome 18

What chromosome is the MNS system on?

Chromosome 4

What chromosome is the P/glob system on?

P system = chromosome 22

Glob system = chromosome 3

Which chromosome is the Lewis (LE) system on?

Chromosome 19

Same as LU

What chromosome is the Lutheran system on?

Chromsome 19

Same as LE

Which blood type is linked to increased thrombosis risk?

ABO

What condition does Fy(a-b-) phenotype protect against?

Plasmodium Vivax Malaria

Which antigen is a receptor for parvovirus B19?

P antigen (P/Glob system)

What disease is associated with Rh null syndrome

Chronic hemolytic anemia and stomatocytosis

Which systems’s null phenotype causes spontaneous abortions

P/Glob (anti-PP1Pk).

Which blood group antigen is a receptor for Plasmodium falciparum (malaria)?

Glycophorin A (MNS system - M/N antigens) and OK (Oka) antigen.

• MNS variants (e.g., En(a-)) may confer partial malaria resistance.

• Oka-negative individuals are rare but potentially protected.

Which antigens are destroyed by ficin/papain?

Duffy (Fya, Fyb), MNS (M, N, S, s), Lutheran (Lua, Lub).

Which antigens are enhanced by enzymes?

Rh (D, C, c, E, e), Kidd (Jka, Jkb), Lewis (Lea, Leb).

Which major blood group systems show dosage effects (stronger reactions in homozygous individuals)?

• Rh (D, C, c, E, e)

• MNS (M, N, S, s)

• Duffy (Fya, Fyb)

• Kidd (Jka, Jkb)

Key Example:

• Anti-c reacts more strongly with c/c cells than C/c cells.

Which systems do not exhibit dosage?

• ABO (A/B antigens are equally strong regardless of genotype).

• Lewis (Lea, Leb) (antigens are absorbed from plasma, not synthesized on RBCs).

• P/Glob (P1, P) (no difference in expression between hetero-/homozygous).

• Lutheran (Lua, Lub) (minimal dosage observed).

Exception:

• Kell (K/k) shows weak dosage (anti-K reacts slightly stronger with K/K cells).

Which antibodies fix complement?

• ABO: Anti-A, Anti-B (cause intravascular hemolysis)

• Lewis: Anti-Lea, Anti-Leb (rarely clinically significant)

• P/Glob: Anti-PP1Pk (causes severe HTRXN)

• Kidd: Anti-Jka, Anti-Jkb (extravascular hemolysis)

Does anti-D (Rh) fix complement?

No – Rh antibodies cause extravascular hemolysis via macrophages.

Does anti-K (Kell) fix complement?

No – Kell antibodies suppress erythropoiesis (unique mechanism).

Which antibodies cause severe HDN?

• Rh: Anti-D, Anti-c (most severe)

• Kell: Anti-K (suppresses fetal erythropoiesis)

• Duffy: Anti-Fya (mild HDN)

• Kidd: Anti-Jka (rare but severe)

Killin’ Kidds is Darn Risky

Which antibodies cause fatal HTRXN?

• ABO: Anti-A, Anti-B (acute intravascular hemolysis)

• Kidd: Anti-Jka, Anti-Jkb (delayed HTRXN)

• P/Glob: Anti-PP1Pk (complement-mediated)

Do Lewis antibodies cause HDN?

Rarely – IgM the doesn’t cross placenta, but IgG may cause mild HDN.

Does anti-Lub (Lutheran) cause HDN/HTRXN?

No – Clinically insignificant.

Which antigen has >99.9% frequency (high incidence)?

• ABO: H antigen (hh/Bombay is ultra-rare)

• Rh: e antigen (98% in most populations)

• Kell: k antigen (99.8%)

• Duffy: Fy3 (100% except Fy(a-b-) individuals)

Everybody Hates Feeling Extra-Known.

Which antigens are low incidence (<10%)?

• Kell: K (9%), Kpa (2%)

• Duffy: Fyb (22% in Blacks)

• Lutheran: Lua (5%)

• MNS: S (55% Caucasians, 31% Blacks)

Population-Specific Frequencies:Population-Specific Frequencies:

• y(a-b-): 68% West Africans (malaria resistance).

• Jk(a-b-): Rare except Polynesians (0.9%).

How to remember enzyme-sensitive antigens?

"Muffin and Duffy Melt; Rh and Kidd Kick."

• Melted (destroyed):
  MNS (M, N, S, s)
  Duffy (Fya, Fyb)

• Kick into gear (enhanced):
  Rh (D, C, E, c, e)
  Kidd (Jka, Jkb)

Why it works: The imagery of sweet, soft things melting (Muffin = MNS, Duffy = delicate) vs. tough fighters (Rh, Kidd = rise/kick) aids differentiation.

How to recall HDN-causing antibodies?

"Killin’ Kidds is Darn Risky."

• Kell

• Kidd

• D (Rh)

• Rh (e.g. anti-c)

Why it works: The grim pun helps you remember that these are dangerous to newborns — they cross the placenta and cause hemolytic disease of the newborn.

How to remember high-frequency antigens?

"Everybody Hates Feeling Extra-Known."

• E (Rh)

• H (H system)

• Fyb3 (Duffy glycoprotein — Fy3)

• k (Kell system, Cellano)

Alternative shorter version:
"Heck, Everybody's Frequent (H, e, k, Fy3)."

Why it works: It captures the sense of commonness ("frequent flyers") and still drills in the key letters.

Clinically Significant Extras

• ABO: Always clinically significant (HTRXN).

• Kell: Anti-K causes both HDN and HTRXN (unique erythropoietic suppression).

• Lewis: Antibodies often disappear in pregnancy (antigens absorbed into plasma).

• Lutheran: Antibodies are rare and benign.