A Brief Overview of Inborn Errors of Metabolism

Inborn errors of metabolism, also known as congenital metabolic diseases, are a comprehensive class of rare genetic conditions that involve congenital disorders of enzyme activities in the body. 

The condition affects one out of 1500 individuals every year. Enzymes inside our body help turn food into energy via metabolism. However, at times, due to a genetic fault, the enzymes cannot process food directly. Substances like amino acids (proteins), sugars, and other toxins accumulate in the body and interfere with normal functioning. In addition, such accumulation of unwanted substances can also damage the nervous system, cause liver problems, result in intellectual disability, and so forth. Some examples of inborn errors in metabolism are –

  • Maple syrup urine disease (MSUD)
  • Mitochondrial disorders
  • Fructose intolerance
  • Galactosemia
  • Fatty acid oxidation defects
  • Lysosomal storage disorders 

Symptoms of Inborn Errors of Metabolism 

Most inborn errors of metabolism manifest in infancy or childhood, and some mild conditions can show up during adulthood. Certain foods may trigger the symptoms of the disease. It is noteworthy to remember that the precise symptoms depend on the underlying condition within the 'inborn errors of metabolism' umbrella. However, some common signs of inherited metabolic conditions include –

  • Poor appetite
  • Inability to gain weight
  • Jaundice
  • Developmental delay
  • Breathing problems, such as apnea or tachypnea
  • Lethargy
  • Vomiting
  • Weight loss
  • Coma
  • The abnormal or uncanny odour of urine, breath, saliva, or sweat 

Causes of Inborn Errors of Metabolism

As the name suggests, inborn errors of metabolism are caused by genetic defects or mutations. Certain chemicals called enzymes facilitate metabolic processes in the body. However, a fault in the code of a gene that controls the production of a particular enzyme can result in a malfunctioning enzyme or reduced quantity of the enzyme, ultimately affecting the body's metabolic pathways. Genetic mutations can occur in the individual for the first time or may be inherited from parents. 

When to See a Doctor

During adulthood, the optimal time to see a doctor for inborn errors of metabolism is after the manifestation of some symptoms, such as lethargy, appetite loss, weight loss, inability to gain weight, and so forth. However, for infants and children, it is possible and may be recommended to consult a doctor or healthcare provider before the manifestation of symptoms. 

In addition, dozens of congenital metabolic diseases are now detectable through newborn screening, which is a protocol specially designed to diagnose the condition in asymptomatic infants and prevent severe damage to the child's organs.

Risk Factors

Anybody with a history of this disorder in their family is at a higher risk of developing it themselves.

Complications of Inborn Errors of Metabolism 

Some of the complications associated with errors of inborn metabolism among children and infants are –

  • Organ failure
  • Damage to the nervous system
  • Intellectual developmental problems
  • Respiratory failure
  • Liver enlargement
  • Immunodeficiency
  • Joint and muscle pain
  • Failure to grow physically and more

Treatments of Inborn Errors of Metabolism

The treatments of inborn errors of metabolism aim to limit the toxicity of substrates in the cell. If done at an early phase, the major complications of the diseases, such as developmental delay, can be prevented. Some of the standard techniques used to treat inherited metabolic disorders are –

  • Removing toxic chemicals accumulated in the body by treating the blood with purifying chemicals
  • Using special diets to eradicate the consumption of foods the body cannot metabolise
  • Replacing the missing or inactive enzymes in the body with an enzyme supplement to restore the body's metabolism


In a nutshell, the error of inborn metabolism is an umbrella of genetic diseases that affect the enzymes and metabolism within the body. The condition primarily manifests in infancy, and immediate treatment is imperative to prevent severe complications. Therefore, if you witness any sign of inborn errors of metabolism or anything unusual in your child, consult your healthcare provider immediately.

Request an appointment at Apollo Cradle, Hyderabad - Kondapur. Call 1860-500-1066 to book an appointment.

1. What are the different tests available to diagnose inborn errors of metabolism?

Multiple tests are available to diagnose inborn errors of metabolism, which include –
1. Genetic Testing
2. Newborn Screening Tests
3. Plasma Amino Acid test
4. Urine Organic Acid Test

2. What is Lysosome storage disorder?

It is a type of inborn error in metabolism. Lysosomes are specialized units within our cells that break down waste products. A lack of lysosome enzymes results in the accumulation of toxins in the cells.

3. Who was the first person to study inborn errors of metabolism?

British physician Archibald Garrod first examined inborn errors of metabolism in 1908. He is known for devising the– 'one gene-one enzyme' hypothesis in its embryonic stage.

4. What is Classic Galactosemia?

It is an inborn error of metabolism wherein the body cannot break down galactose, which is a sugar found in milk. The condition occurs because of a deficiency in the enzyme called GALT.

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