Not-So-Usual Suspects Deck

Diego (Dia/Dib) antigen disease link?

Hereditary spherocytosis (band 3 protein defects)

Cartwright (Ytᵃ/Ytᵇ) antigen disease link?

Neuromuscular disorders (acetylcholinesterase dysfunction)

OK (Oka) antigen disease link?

Malaria receptor (Plasmodium falciparum invasion)

Cromer (Cra/Tcb) antigen disease link?

Paroxysmal nocturnal hemoglobinuria (CD55 deficiency)

Indian (Inᵃ/Inᵇ) antigen disease link?

Cancer metastasis (CD44 overexpression)

Gerbich (Ge2/Ge3) antigen disease link?

Elliptocytosis (glycophorin C/D defects)

Which systems are destroyed by ficin/papain?

• Dombrock (Doᵃ/Doᵇ)

• Gerbich (Ge2/Ge3)

• Cromer (Cra/Tcb)

• Knops (Knᵃ/Knᵇ)

Which system is enhanced by enzymes?

Colton (Coᵃ/Coᵇ)

Carthwright

JMH

Which systems are resistant to enzymes?

• Diego (Dia/Dib)

• Scianna (Sc1/Sc2)

• Landsteiner-Weiner (LWᵃ/LWᵇ)

Which Systems cause HDN

Diego rare, mild,

Colton,

Vel, severe

Jra rare severe

Can anti-Vel cause HTRXN?

Yes (acute, potentially fatal)

Can anti-Doᵃ cause HTRXN?

Yes (delayed)

Why is anti-Vel dangerous?

Causes severe HTRXN/HDN; anti-Vel negative blood often scarce

Why is anti-Jrᵃ problematic?

High prevalence in Japanese; causes severe HDN

What’s unique about anti-Ch/Rg?

Neutralized by plasma (C4-derived antigens)

Why is Sdᵃ clinically insignificant?

IgM antibody, doesn’t react at body temp

Where is Jr(a-) phenotype common?

Japan (up to 1%)

Where is Diᵃ antigen prevalent?

South Americans (>5%)

Where is Vel-negative phenotype rare?

All populations (<0.1%)

How to remember complement-fixing unusual antibodies?

"Vel Chugs Complement!"

• Vel, Chido/Rodgers (Ch/Rg) → fix complement

Why it works:
"Chugs" links Chido and complement, while “Vel” feels like a bold character. It's tight and energetic — easy to recall in a crunch.

How to recall HDN risks?

Junior Diego’s Velcro Blanket = Bad for Babies."

• Jra, Diego (Dia), Vel → associated with HDN

Why it works:
Gives a visual image: a baby wrapped in a dangerous "Velcro blanket" made by “Junior Diego” — easy to remember, unusual, and ties all three systems together in a single metaphor.

How to identify enzyme-sensitive systems?

"Don't Get Crazy Kissing Enzymes."

• Dombrock

• Gerbich

• Cromer

• Knops
  → all are destroyed by enzyme treatment

Why it works:
It maintains your system initials but makes them memorable with a silly, slightly taboo image (crazy kissing enzymes). It's funny and weird enough to stick.

Which uncommon blood group systems produce antibodies that do NOT cause HDN or HTR (i.e., are not clinically significant)?

• Chido/Rodgers (Ch/Rg) — HTLA; complement absorbed, neutralized by plasma

• Xg (Xgᵃ) — X-linked, cold-reacting IgM; not clinically significant

• Scianna (Sc1/Sc2) — significance unclear; resistant to enzymes/chemicals

• Knops (Kn, McC, Sl) — HTLA; weak reactivity, no clinical impact

• John Milton Hagen (JMH) — seen in elderly, HTLA, DAT+

• Sid (Sda) — naturally occurring IgM; neutralized by urine

• Human Leukocyte Antigen (HLA – Bga/Bgb/Bgc) — no HDN; some platelet HTRs only

• Cromer (Cra, Dra, Tca) — no HDN (DAF on placenta); mild/rare HTRs only

Xtra Silly Characters Just Keep Hiding Cool Secrets.

Each word cues you to a non-clinically significant antigen system (i.e., doesn’t cause HDN or HTR):

• Xtra → Xgᵃ

• Silly → Scianna (Sc)

• Characters → Chido/Rodgers (Ch/Rg)

• Just → JMH (John Milton Hagen)

• Keep → Knops (Kn, McC, Sl)

• Hiding → HLA (Bga, Bgb, Bgc)

• Cool → Cromer (Cra, Dra, Tca)

• Secrets → Sda (Sid antigen)