An evidence-based guide
MCADD,
made clear.
Medium-chain acyl-CoA dehydrogenase deficiency — explained from the simple to the deeply scientific, so you can understand it, live safely with it, and follow the research that matters.
- Incidence (US)
- 1 in 17,000
- Most common mutation
- K304E (c.985A>G)
- Cornerstone of care
- Avoiding fasting
The 30-second version
Your body usually runs on two fuels: sugar and fat. Between meals and overnight, it switches to burning fat for energy. In MCADD, an enzyme that helps burn a certain type of fat (medium-chain fats) does not work properly.
Most of the time this causes no problem. But if a person with MCADD goes too long without food — especially during illness — the body can run out of usable energy while partly processed fats build up. That can lead to a dangerous metabolic crisis.
The good news: this is largely preventable. Avoiding long periods without food and having an emergency plan mean most people with MCADD live healthy, normal lives.
A term to know
Hypoketotic hypoglycemia
Low blood sugar with unusually low ketones — the signature of an MCADD crisis.
Browse the glossary →Explore the guide
Five paths through the knowledge base — start anywhere, go as deep as you like.
Understanding MCADD
What MCADD is, how the MCAD enzyme works, the genetics behind it, and what happens in the body during fasting — from the simple explanation to the biochemistry.
DiagnosisDiagnosis & biomarkers
How MCADD is detected through newborn screening, how the diagnosis is confirmed, and what the blood markers — especially C8 — actually mean.
LivingLiving with MCADD
Practical, day-to-day guidance: preventing fasting, eating well, exercising safely, managing illness, and having an emergency plan in place.
EmergencyEmergency situations
Recognising the warning signs of a metabolic crisis and knowing exactly what to do — including when to call emergency services immediately.
ResearchResearch & clinical trials
The latest trials and emerging therapies, clearly separated into established knowledge, ongoing research, and experimental work.
3 trials currently recruitingMCADD is a guide, not a doctor. All medical content here is traced to published, cited sources — verified 2026-08-21 — but your metabolic team knows your MCADD best.