A 5-year-old boy from South India presents with acute hemolytic anemia following ingestion of fava beans. Heinz bodies are seen on supravital staining. What is the most common enzymatic defect causing hemolytic anemia in this patient's population?

Question

Accepted Answer

A. Glucose-6-phosphate dehydrogenase deficiency. ## G6PD Deficiency: Most Common Enzymatic Hemolytic Anemia

**Key Point:** Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymatic defect of glycolysis causing hemolytic anemia, affecting >400 million people worldwide, with highest prevalence in Africa, Mediterranean, and South Asian populations.

### Epidemiology
- **X-linked recessive** inheritance (males predominantly affected)
- **Prevalence in India:** 5–15% in certain populations
- More common in males; heterozygous females may show mild symptoms

### Pathophysiology
G6PD catalyzes the first step of the pentose phosphate pathway, generating NADPH for antioxidant defense:

$$	ext{Glucose-6-phosphate} \xrightarrow{G6PD} 	ext{6-phosphogluconolactone} ightarrow 	ext{NADPH}$$

Deficiency → ↓NADPH → ↓glutathione reduction → oxidative stress → RBC hemolysis

### Triggers for Acute Hemolytic Episodes
- **Fava beans** (classic trigger; hence "favism")
- Oxidative drugs: sulfonamides, aspirin, antimalarials (primaquine), nitrofurantoin
- Infections (bacterial, viral)
- Acidosis, hypoxia

### Diagnostic Features

| Test | Finding |
|------|----------|
| **Heinz bodies** | Present on supravital staining (denatured hemoglobin precipitates) |
| **G6PD enzyme assay** | Reduced activity |
| **Blood film** | Bite cells, blister cells (RBCs with Heinz bodies removed by spleen) |
| **Reticulocyte count** | Elevated during hemolytic episode |
| **Indirect bilirubin** | Elevated |

**High-Yield:** **Heinz bodies on supravital staining** are pathognomonic for G6PD deficiency during acute hemolysis.

**Mnemonic:** **FAVA** = Favism, Antimalarials, Aspirin, Antibiotics (sulfonamides) — common triggers

**Clinical Pearl:** Most G6PD-deficient individuals are asymptomatic; hemolysis occurs only with oxidative stress. Neonatal jaundice may be the first presentation.

Answer

B. Phosphofructokinase deficiency

Answer

C. Hexokinase deficiency

Answer

D. Pyruvate kinase deficiency

A 5-year-old boy from South India presents with acute hemolytic anemia following ingestion of fava beans. Heinz bodies are seen on supravital staining. What is the most common enzymatic defect causing hemolytic anemia in this patient's population?

Explanation

G6PD Deficiency: Most Common Enzymatic Hemolytic Anemia

Epidemiology

Pathophysiology

Triggers for Acute Hemolytic Episodes

Diagnostic Features

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Test	Finding
Heinz bodies	Present on supravital staining (denatured hemoglobin precipitates)
G6PD enzyme assay	Reduced activity
Blood film	Bite cells, blister cells (RBCs with Heinz bodies removed by spleen)
Reticulocyte count	Elevated during hemolytic episode
Indirect bilirubin	Elevated