When to suspect an inherited metabolic disease

Here are seven cardinal clues to the presence of an inherited metabolic disease (“inborn error of metabolism”):

1. Normal pregnancy and birth, but the infant begins to deteriorate after an asymptomatic interval (usually after the first 24 hours of life)
2. Symptoms are precipitated or exacerbated by changes in metabolic state or dietary habits: feeding, starvation, dietary changes, or exertion.
3. Progressively worsening dysmorphic features
4. Unusual or suspicious family history: consanguinity or early death, particularly in infancy
5. Peculiar odor
6. Bizarre laboratory abnormalities (e.g., ammonia > 200 → urea cycle defects)
7. Persistent or worsening symptoms despite a reasonable and standard initial workup and management (e.g., sepsis workup with empiric antibiotic treatment).