Interesting Facts About Methylmalonic Aciduria
Methylmalonic aciduria is usually diagnosed in the first year of life. Symptoms can be clearly seen during childhood but vary in each patient.
Methylmalonic aciduria is a rare, hereditary metabolic disorder associated with the absorption of vitamin B12. The body cannot break down certain proteins and fats because methylmalonic acid accumulates in the blood.
This disease is usually diagnosed in the first month of life. About 1 child between 25,000 and 48,000 is born with this disease. Symptoms are evident in childhood but vary in each patient.
Methylmalonic aciduria: causes
The cause of vitamin B12-sensitive methylmalonic aciduria is a disruption of the synthesis of the cofactor adenosylcobalamin (AdoCbl) due to genetic changes in the genes MMAA (4q31.1-2), MMAB (12q24.1) and MMADHC (2q23.2).
Vitamin B12-resistant methylmalonic aciduria is triggered by a reduced or non-existent activity of the enzyme methylmalonyl-CoA mutase. In this case there is a mutation in the MUT (6p21) gene.
However, all forms of the disease are passed on through the same autosomal recessive inheritance pattern.
Symptoms
Recurrent vomiting, dehydration, hypotension (low blood pressure), developmental delays, fatigue, and hepatomegaly (enlarged liver) may indicate this disease. In the long term, the following complications can also arise:
- Nutritional problems
- Intellectual disk capacity
- Chronic kidney disease
- Pancreatitis (inflammation of the pancreas)
If affected children do not receive the appropriate treatment, they can fall into a coma or die. If it is isolated methylmalonic aciduria, the following symptoms may also occur, depending on the form of the disease:
Isolated methylmalonic aciduria in children (isolated homocystinuria)
Vitamin B12-resistant methylmalonic aciduria is the most common isolated form. It occurs in childhood, but affected children show no signs of it at birth. But symptoms such as lethargy, vomiting and dehydration can quickly be observed.
After that, the enlargement of the liver becomes evident and other signs such as hypotension and encephalopathy (abnormal state of the brain) develop. The following parameters are measured on the basis of laboratory analyzes:
- Ketosis and ketonuria
- Ammonium in the blood
- Severe metabolic acidosis
- Increased levels of glycine in the blood
Vitamin B12 sensitive form
This form of methylmalonic aciduria occurs in the child’s first months or years of life. Affected people suffer from eating disorders such as anorexia with vomiting, hypotension and developmental disorders.
In some cases, vomiting may occur after consuming proteins. Affected children are also at risk of metabolic decompensation. Therefore, early diagnosis and treatment is essential.
In general, however, the disease is not recognized until episodes of vomiting, dehydration, lethargy, or coma occur.
Benign form in adults
Even when affected individuals achieve stability, they may be more prone to acute metabolic decompensation.
The cause of this type of methylmalonic aciduria has not yet been adequately researched.
Methylmalonic aciduria: treatment
Treatment begins immediately after diagnosis. The earlier this happens, the better the patient’s development. Currently, a specific diet is the basis of treatment for methylmalonic aciduria. The purpose of this is to prevent toxic amounts of substrates and metabolites from building up.
Children are usually treated as follows:
- L-Carnitine: This safe and natural substance helps the organism to produce energy and excrete residues.
- Orally administered antibiotics: These can reduce the amount of methylmalonic acid in the intestine.
- Vitamin B12 injections: This treatment helps in over 90% of cases with a CblA deficit. It is also used successfully in 40% of children with a CblB deficit.
If symptoms of a metabolic crisis are present, the person concerned must be hospitalized immediately. Inpatient treatment includes intravenous administration of bicarbonate to reduce the acidity in the blood.
Glucose is also injected intravenously to prevent the breakdown of protein and fat stored in the body.
prevention
A diet low in amino acids and a limited amount of protein is recommended . Specifically, the diet includes carbohydrates such as cereals, fruits, pastas, and vegetables.
People must avoid contact with anyone who has a contagious disease (such as the flu or a viral cold) to avoid complications.
