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What are metabolic causes?

The body contains many enzymes that are responsible for breaking down the various parts of the food we eat to nourish the body. If there is underactivity or blockage in one of these enzymes, this can lead to problems metabolizing or “breaking down” one of the components in food (proteins, carbohydrates or “sugars,” fats or “lipids” or vitamins) or problems generating energy to sustain the body’s function.

Disorders in these processes are called Metabolic Disorders, and there are over 750 different types. Each is very rare but collectively, they affect approximately 1 in 3,000 persons.

What are the symptoms?

The majority of persons with metabolic epilepsy present with symptoms in infancy or early childhood, which often includes seizures, typically with other symptoms such as:

  • Delayed development or loss of skills
  • Abnormal movements
  • Problems with other body organs such as the liver or kidneys

How do you get a metabolic disorder?

Most of these disorders are inherited genetically. The inheritance pattern is usually autosomal recessive or X-linked recessive.

Autosomal Recessive Disorder

  • To have an autosomal recessive disorder, the person must have two copies of the abnormal gene. Usually, they inherit one of these copies from each parent. Each parent is a carrier, meaning that they have one abnormal gene (recessive gene) and one normal gene (dominant gene) for the condition, but their health is normal, as they have a normal gene.

X-Linked Recessive Inheritance

  • X-linked recessive inheritance means that the gene causing the trait or the disorder is located on the X chromosome, and that the disorder is only present if a second, normal copy X chromosome is not present. Females have two X chromosomes. Males have one X and one Y chromosome.  Because females typically have one abnormal gene and one normal gene, they are carriers and are not affected.
  • When a carrier female has children with an unaffected male, their sons will have a 50% chance of inheriting the abnormal gene. All sons who inherit that gene will be affected. However, daughters will not be affected, but will have a 50% chance of being a carrier, as they have a 50% chance of inheriting the abnormal gene from their mother, but will inherit a normal X chromosome from their father.

How do you treat it?

Some, but not all metabolic disorders have very specific treatments which may stop or attenuate the seizures and other symptoms. The earlier these treatable conditions are recognized, the better the outcome.

Types of Metabolic Disorders

Authored By: 
Elaine Wirrell MD
Authored Date: 
12/2020