Inherited metabolic disorders

Overview

Inherited metabolic disorders are medical conditions caused by changes in specific genes that affect metabolism. Different gene changes cause different types of inherited metabolic disorders. These gene changes are most commonly passed down from both parents. But sometimes the gene change comes only from one parent, most often from the mother. These disorders also are called inborn errors of metabolism.

Metabolism is the complex set of chemical reactions that your body uses to maintain life. These include:

• Making energy. Special enzymes break down food or certain chemicals so your body can use them right away for fuel or store them for later use.
• Making or getting rid of substances. Certain chemical processes make substances your body needs. Other chemical processes break down substances that your body no longer needs.

When these processes don't work properly, a metabolic disorder occurs. It may be due to an enzyme that's too low or missing or to another problem. Inherited metabolic disorders fall into different groups. They're grouped by the substance affected and whether it builds up too much because it can't be broken down or it's too low or missing.

Symptoms

There are hundreds of inherited metabolic disorders caused by different genes. Symptoms depend on the type of disorder and how severe it is.

Examples of inherited metabolic disorders 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.

When to see a doctor

If you have concerns about your child's growth and development or your own health, talk to your doctor or other healthcare professional.

Causes

Inherited metabolic disorders are caused by changes in specific genes that affect metabolism. Different gene changes cause different types of inherited metabolic disorders. These gene changes are most commonly passed down from both parents. But sometimes the gene change comes only from one parent, most often from the mother. There are hundreds of inherited metabolic disorders caused by different genes.

Risk factors

The risk of an inherited metabolic disorder is higher if one or both parents have the gene change that can cause the condition. In some cases, future parents may decide to have carrier testing before pregnancy. This test can identify some gene changes in parents that may raise the risk that future children will have certain types of inherited metabolic disorders.