Very long-chain acyl-coenzyme A dehydrogenase deficiency

Very long chain acyl coenzyme A dehydrogenase deficiency is a fatty acid metabolism disorder which prevents the body from converting certain fats to energy, particularly during periods without food. Those affected by this disorder have inadequate levels of an enzyme that breaks down a group of fats called very long chain fatty acids.

VLCAD (very long chain acyl dehydrogenase) deficiency is exclusively linked to genetic mutations in DNA. A change of the gene that codes for very long chain acyl CoA dehydrogenase (VLCAD) results in a deficiency or malfunction of the produced VLCAD enzyme. This mutation occurs on chromosome 17 and can be altered via a variety of pathways. However, it is still unknown at to what causes the disease to manifest itself in the different life stages.

Typically, initial signs and symptoms of this disorder occur during infancy and include low blood sugar (hypoglycemia), lack of energy (lethargy), and muscle weakness. There is also a high risk of complications such as liver abnormalities and life threatening heart problems. Symptoms that begin later in childhood, adolescence, or adulthood tend to be milder and usually do not involve heart problems. Episodes of very long chain acyl coenzyme A dehydrogenase deficiency can be triggered by periods of fasting, illness, and exercise. It is common for babies and children with the early and childhood types of VLCAD to have episodes of illness known as metabolic crises. Some of the first symptoms of a metabolic crisis are: extreme sleepiness, behavior changes, irritable mood, poor appetite. Some of these other symptoms of VLCAD in infants may also follow: fever, nausea, diarrhea, vomiting, hypoglycemia. Evaluation of symptom combinations can aid in a positive diagnosis of VLCAD. Since symptoms vary depending on age and onset of the patient, consultation with a metabolic specialist should be considered. Diagnosis is further confirmed through genetic analysis of the VLCAD gene. Avoidance of fasting periods, high fat diets, and dehydration is recommended for those who are affected. A diet consisting of low fat intake and supplemental calories is common for management of VLCAD deficiency. If a metabolic crisis is not treated, a child with VLCAD can develop: breathing problems, seizures, coma, sometimes leading to death.

Medical screening can confirm occurrences of VLCAD most often in neonatal and infancy stages. Approximately half of all patients show signs of VLCAD deficiency during the neonatal period, one fourth present later in the first year of infancy, and the final quarter is split between manifestations in childhood and adulthood. Comorbidity of cardiomyopathy, arrhythmias and rhabdomyolysis are extremely common in patients under 1 year old which can lead to complications later in life. Loss of awareness or seizure can occur from hypoketotic hypoglycemia, which is often fatal if not caught in screening. However, prompt treatment shows high promise for improvement. People who develop late onset myopathic may only experience muscle related, vague, sporadic symptoms, and may never be diagnosed. There is an extremely high genotype phenotype correlation in a presentation. Mitigation of VLCAD symptoms can be achieved through dietary management.