Introduction:
Ornithine transcarbamylase (OTC) deficiency is a rare genetic disorder that primarily affects the liver and kidneys. OTC deficiency is a genetic disorder passed down from parents to children. A mutation acquires this deficiency in the OTC gene, which is responsible for producing the enzyme ornithine transcarbamylase. In people with OTC deficiency, the body cannot process proteins efficiently. Specifically, the body has trouble breaking down arginine and its related compounds. This leads to high levels of ammonia in the bloodstream and other complications as a result. This article will explain everything about ornithine transcarbamylase deficiency - causes, symptoms, diagnosis, and treatment.
What Is Ornithine Transcarbamylase?
Ornithine transcarbamylase is an enzyme that catalyzes the formation of carbamoyl phosphate from ammonia and ornithine. Carbamoyl phosphate is essential to the urea cycle, which removes ammonia and regulates blood pressure. While there are different degrees of severity, in any case, the deficiency leads to high ammonia levels in the blood and an inability to break down proteins.
What Are the Causes of Ornithine Transcarbamylase Deficiency?
OTC deficiency is caused by a gene mutation regulating the production of a protein called ornithine transcarbamylase. This protein breaks down arginine and related compounds into other substances. When this gene is mutated, it disrupts the normal production of the ornithine transcarbamylase protein, leading to an OTC deficiency. This OTC deficiency leads to ammonia buildup in the bloodstream. Ammonia is a byproduct of the breakdown of proteins. In people with OTC deficiency, ammonia does not get broken down properly and instead travels through the bloodstream. Different gene mutations cause different types of OTC deficiency.
How Does OTC Deficiency Affect the Body?
The buildup of ammonia in the bloodstream causes many complications in the body. Most notably, it can lead to liver damage and scarring. High ammonia levels can damage the liver cells and cause them to die. In addition, ammonia can be converted into other substances that can cause further damage to the liver. The liver is responsible for filtering many substances out of the body. It converts ammonia into urea and then excretes it into bile and out of the body when you have a bowel movement. In people with OTC deficiency, the liver cannot efficiently break down ammonia into urea. This leads to ammonia in the bloodstream and other body areas. This can cause permanent damage to the liver and liver failure.
What Are the Symptoms of Ornithine Transcarbamylase Deficiency?
The severity of OTC deficiency and the individual symptoms can vary significantly from person to person. Some people may not experience any symptoms or may only experience mild ones. The most common symptoms of OTC deficiency are fatigue, nausea, vomiting, weakness, and jaundice (yellowing of the skin). Some people may also experience vomiting triggered by certain foods, especially protein-rich foods. While the symptoms can vary, people with OTC deficiency will often test positive for high ammonia levels in the bloodstream. People with OTC deficiency have fewer symptoms but lower blood ammonia levels. These symptoms include developmental delay, lethargy, and short-term memory loss.
What Is the Diagnosis of Ornithine Transcarbamylase Deficiency?
OTC deficiency is diagnosed by reviewing a patient’s symptoms, lab results, and family history. Ornithine transcarbamylase deficiency is typically diagnosed in infancy or early childhood. One of the most common diagnostic tools is measuring blood urea nitrogen levels (BUN). Elevated levels of BUN can indicate OTC deficiency. In addition to BUN, other tests available for diagnosing OTC deficiency include urinary orotic acid levels, ornithine levels, glutamine levels, and alanine levels. Citrulline levels may also be measured as relatively low citrulline levels can be a finding in OTC deficiency.
By testing blood levels of arginine and ornithine and protein levels in the blood or urine, doctors can determine if OTC deficiency is present and what type of deficiency it is.
What Is the Treatment of Ornithine Transcarbamylase Deficiency?
The treatment of OTC deficiency depends on the severity and type of the diagnosis. The condition is usually managed with dietary restrictions and nutritional support. Those with severe forms of OTC deficiency may be prescribed medications to help break down ammonia in the bloodstream.
One is hemodialysis, a process of filtering blood to remove toxins. Another is to give the person IV infusions of sodium benzoate, arginine, and sodium phenylacetate.
The person with ornithine transcarbamylase deficiency will also need to discontinue protein intake temporarily. This is because protein is what produces ammonia in the body. By discontinuing protein intake, the person with ornithine transcarbamylase deficiency can reduce the amount of ammonia in their body and prevent further damage.
How to Manage OTC Deficiency?
Since OTC deficiency is a lifelong condition, diet is extremely important. The important point to note is to avoid high-protein foods and drink lots of water. For most people with OTC, a low-protein diet is sufficient. This means avoiding red meat, fish, poultry, cheese, milk, beans, nuts, and seeds. Foods high in carbohydrates and fats are also avoided because they are less likely to cause flare-ups. A low-protein, low carbohydrate, and high-fat diet may be necessary for people with a low-carbohydrateform of OTC deficiency and an accompanying condition. This diet may also be necessary for people with a metabolic disorder.
Conclusion:
The best way to prevent OTC deficiency is to eat a balanced diet and avoid protein-rich foods that may trigger vomiting. If left untreated, ornithine transcarbamylase deficiency can be life-threatening. Fortunately, it can be treated with a special diet and a medicine called arginine, which allows the body to produce a substance called citrulline.
