Types of Enzyme Deficiency

When the production of key enzymes is missing or deficient at birth, it causes disease. Most enzyme deficiencies are genetic disorders that lead to errors in metabolism. When there is an error in metabolism, the body cannot process chemicals efficiently, which can lead to dysfunction.

Enzymes are small proteins located inside cells that help support chemical reactions important for managing sugar, vitamin, protein, and fat levels which are essential for body functions. Thousands of different enzymes play crucial roles in metabolism.

Hundreds of different metabolic disorders can impact every system in the body. Determining which specific enzymes are deficient and understanding the processes that those enzymes control are key to defining the symptoms and available treatment approaches.

This article will discuss the different enzyme deficiencies, how they cause disease, and how they are treated.

Role of Enzymes in Metabolism

Enzymes play an integral role in controlling metabolism within the body. The body is responsible for taking raw products from foods and turning them into useful products that support cellular and metabolic functions.

Chemical reactions within the body coordinate processes across all levels of the body, from controlling synaptic transmission in the brain to ensuring you have enough energy stored in your muscles for your next workout.

Enzymes help catalyze and speed up these chemical processes within the body. Most enzymes are small proteins that live within cells. Most enzymes have very specific functions in the body. Disruptions in even a single enzyme can lead to the development of metabolic diseases, also known as inborn errors of metabolism.

Since the body is responsible for processing many different molecules, each disorder is usually tied to a specific enzyme deficiency or the specific molecule that builds up within the body.

Types of Enzyme Deficiencies

There are many different types of enzyme deficiencies and understanding the chemistry can be a daunting task. Enzyme deficiencies are often classified based on the metabolic pathway that they disrupt or the products that accumulate in the body.

A few enzyme deficiency disorders are:

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency: In this enzyme deficiency, free radicals (unstable molecules) can build up in and damage red blood cells, leading to anemia. This condition is more commonly found in males who have African, Middle Eastern, Mediterranean, or Asian (certain areas) ancestry.
• Glucose metabolism deficiencies: These are deficiencies in any of the enzymes that are responsible for processing glucose, or sugar, into energy that the body can use.
• Glycogen storage disorders: The body stores glucose for long-term use in the form of glycogen. When crucial enzymes are deficient this can lead to disruptions in the storage processes and the development of conditions such as Pompe disease or Cori disease.
• Urea cycle disorders: The body produces ammonia as it breaks down protein. Ammonia is very toxic and it is converted into urea in the liver, which is released in the urine. Some enzyme deficiencies lead to a disruption in the urea cycle and as a result, ammonia can build up in the blood.

Symptoms of Metabolic Disorders

Since metabolic disorders are present at birth, the symptoms often develop early in life. Most commonly, issues such as the inability to gain weight, irritability, and fatigue are present. Recurrent infections and an enlarged liver or spleen are other common symptoms experienced by those who are born with metabolic disorders. 

If your child is consistently unable to gain weight or appears to remain sick despite ongoing treatment, your healthcare provider may consider testing for metabolic disorders.  

Some metabolic disorders are not diagnosed until later in life. Glucose-6-phosphate dehydrogenase deficiency impacts red blood cells. Oftentimes, this disorder may not be significant until later stages of life, and then it is diagnosed.

How Do You Know If You Have an Enzyme Deficiency?

Enzyme deficiencies are usually identified at birth or in early childhood. Every U.S. state performs newborn blood sample screening tests to identify and screen for metabolic disorders. Screening is conducted to identify the most common deficiencies and some rare deficiencies.

However, some deficiencies are delayed and may not become known until later in life. Assessment for metabolic disorders can be performed by a healthcare provider. It is most often performed using blood tests. 

To better understand what enzyme deficiencies your state screens for, you can visit the department of health website for your state and review their newborn screening policies.

Treatment at a Glance

Treatment options for metabolic disorders are variable and depend on the underlying condition and process that are affected. In some cases, specific dietary changes are needed to reduce the effects of an enzyme disorder.

For example, in galactosemia, avoiding milk products is necessary since the body cannot process the molecule galactose, which is found in milk.

In other cases, for example with lysosomal storage disorders (which affect the metabolism of some fats and carbohydrates), options such as enzyme replacement therapy can be used.

Treating an enzyme disorder often requires specialized medical care. Since many enzyme disorders impact multiple regions of the body, you often need a multidisciplinary team of specialists who can coordinate together and recommend a comprehensive treatment plan.

Unfortunately, many enzyme disorders lack effective treatment options. Ongoing work aims to identify and validate new therapeutics to treat these conditions. Recent innovations have brought new therapies and treatments for conditions like Hunter's syndrome and more.   

Ongoing Research Developments

New genetic tools are being researched for metabolic disorders. Since many metabolic disorders result from specific gene defects, there is hope that the disease can be reversed by correcting the underlying gene.

Tools such as CRISPR-CAS9 have been used to treat blood disorders such as sickle cell disease, and there is ongoing research into using these techniques to treat other conditions. Inherited metabolic disorders are optimal targets for these interventions, and work is underway to bring these treatments to the clinic.

Summary

Metabolic disorders are inherited conditions present at birth that impact the body’s ability to process nutrients and eliminate wastes. Determining the specific enzymes that are deficient and the processes they control is necessary to determine the best treatments.

Some enzyme deficiencies have the option for enzyme replacement therapy while other deficiencies can be corrected by changing diet. Research is developing new treatments for enzyme deficiencies.