Inherited metabolic disorders

Overview

Inherited metabolic disorders refer to different types of medical conditions caused by genetic defects — most commonly inherited from both parents — that interfere with the body's metabolism. These conditions may also be called inborn errors of metabolism.

Metabolism is the complex set of chemical reactions that your body uses to maintain life, including energy production. Special enzymes break down food or certain chemicals so your body can use them right away for fuel or store them. Also, certain chemical processes break down substances that your body no longer needs, or make those it lacks.

When these chemical processes don't work properly due to a hormone or enzyme deficiency, a metabolic disorder occurs. Inherited metabolic disorders fall into different categories, depending on the specific substance and whether it builds up in harmful amounts (because it can't be broken down), it's too low or it's missing.

There are hundreds of inherited metabolic disorders, caused by different genetic defects. Examples include:

• Familial hypercholesterolemia
• Gaucher disease
• Hunter syndrome
• Krabbe disease
• Maple syrup urine disease
• Metachromatic leukodystrophy
• Mitochondrial encephalopathy, lactic acidosis, stroke-like episodes (MELAS)
• Niemann-Pick
• Phenylketonuria (PKU)
• Porphyria
• Tay-Sachs disease
• Wilson's disease

Some metabolic disorders can be diagnosed by routine screening tests done at birth. Others are identified only after a child or adult shows symptoms of a disorder.

Treatment for an inherited metabolic disorder depends on the type and severity of the disorder. Because there are so many types of inherited metabolic disorders, treatment recommendations may vary considerably — from dietary restrictions to liver transplants.