Mitochondrial Trifunctional Protein Deficiency 2
OMIM number: 620300
Comments closing date: 17/12/2025
Mitochondrial Trifunctional Protein Deficiency (MTPD), also known as Trifunctional Protein
Deficiency Type 2, is a rare genetic metabolic disorder that prevents the body from properly
converting certain long-chain fats into energy. How it Affects a Person MTPD is a problem with the body’s ‘energy factory’ (the mitochondria)(which when blocked can’t use fats as fuel, especially during fasting or illness. This leads to: • Severe energy shortage (causing low blood sugar/hypoglycaemia and lethargy). • A build up of toxic fatty substances that damage organs. Symptoms can appear in infancy or later in life, ranging from severe (e.g., heart problems, liver issues, and a high risk of sudden death) to milder forms involving muscle weakness (myopathy) and nerve damage (peripheral neuropathy). Inheritance and Treatment MTPD is inherited in an autosomal recessive pattern. This means a child must inherit a faulty gene copy from both parents to be affected. The parents, who only carry one copy, are usually healthy themselves. Treatment focuses on prevention and management, and is available: • Strict avoidance
of fasting with frequent, regular meals and snacks. • A special low-fat, high-carbohydrate diet that
restricts long-chain fats. • Use of Medium-Chain Triglyceride (MCT) oil as an alternative fat source the body can use for energy. • Emergency treatment (usually IV glucose/dextrose) during
illness to prevent a metabolic crisis.
