FRCPath Haem Part 1 MCQ-Gen Haem 380
- amirhayat2527
- 3 days ago
- 0 min read
A 35yr-old woman with long-standing neutrophil count of 1.2 is diagnosed with Duffy-null phenotype. She asks about her risk of infection. Best Answer?
She has impaired neutrophil function
She requires lifelong antimicrobial prophylaxis
Her neutrophils are sequestered in the spleen
She has no increased risk of infection
Correct Answer: She has no increased risk of infection
Mechanism of Duffy-null (ACKR1/Fy)–associated neutropenia
Gene / mutation:
Homozygous mutation in ACKR1 → Duffy-null phenotype (Fy[a-b-])
Effect on chemokines:
ACKR1/Duffy normally binds chemokines on RBCs.
Without Duffy, chemokines remain in circulation at higher levels.
Effect on neutrophils:
High circulating chemokines → enhanced neutrophil margination and migration into tissues.
Result: Lower circulating neutrophil count (ANC ~1–1.5 ×10⁹/L) but normal neutrophil function.
Clinical picture:
Chronic, mild neutropenia
Asymptomatic
No increased risk of infections