Medium chain acyl CoA dehydrogenase deficiency (MCADD) is a metabolic disorder characterized by the body’s inability to convert certain fats into energy particularly during fasting. These affected individuals lack the sufficient amount of an enzyme necessary for the metabolizing of a group of fats called medium-chain fatty acids. The symptoms typically occur during infancy or early childhood and in rare cases are not diagnosed until adulthood.
Causes
MCADD develops as the result of a mutation in the gene ACADM which is responsible for the production of medium-chain acyl-CoA dehydrogenase that is required for the metabolizing of a group of fats called medium-chain fatty acids. Fatty acids are present in various foods and are the major source of energy. The genetic mutation causes the deficiency of the MCAS enzyme within the cells and as the result; the medium-chain fatty acids cannot be properly metabolized. When the fats cannot be properly converted to energy, the associated symptoms of this condition occur. The medium-chain fatty acids can also accumulate in various tissues and damage the brain and the liver. This disorder is inherited in an autosomal recessive pattern meaning both the copies of the gene in each cell are defective. The parents of the affected individual each carry a single copy of the defective gene and don’t necessarily exhibit the symptoms associated with this condition.
Symptoms
The symptoms can include vomiting, low blood sugar (hypoglycemia) and lacking energy. The affected individuals are also at increased risk of developing complications such as breathing difficulties, fatigue, excessive sweating, seizures, brain damage, liver problems and sudden death. The symptoms associated with this condition can be triggered by the periods of not eating (fasting) or as the result of an illness such as infections. The symptoms of this disorder with infants include tiredness, poor appetite, diarrhea, sleeping longer than normal, fever, behavior changes, irritable mood, hypoglycemia and vomiting.
Diagnosis
The newborn spot testing is available for the infants to identify disorders including this condition. The screening is not considered to be 100% accurate and can include further tests such as urine and blood samples to confirm the diagnosis.
Treatment
There is no specific treatment option available for this disorder. The main focus of the treatment is to prevent the development of complications from this condition. Hence, it is essential to include a diet that is high in carbohydrates, to accommodate regular meals and to consume low food low in fat. A dietician can assist with planning a high-carbohydrate diet and a meal that is low in fat content. The affected individuals should also accommodate special high energy drinks during periods of illness such as vomiting, diarrhea and fever. The L-carnitine supplements may also be prescribed for the infants to help the body break down the fats and to remove materials not required.
References
http://www.nhs.uk/conditions/MCADD/Pages/Introduction.aspx
https://rarediseases.info.nih.gov/diseases/540/medium-chain-acyl-coenzyme-a-dehydrogenase-deficiency
https://ghr.nlm.nih.gov/condition/medium-chain-acyl-coa-dehydrogenase-deficiency#inheritance
