Summary about Disease
Methylcrotonyl-CoA carboxylase deficiency (MCCD), also known as 3-methylcrotonylglycinuria, is a rare inherited metabolic disorder. It is caused by a deficiency in the enzyme methylcrotonyl-CoA carboxylase (MCC), which is essential for breaking down the amino acid leucine and other organic compounds. This deficiency leads to a buildup of harmful substances in the blood and urine, potentially causing a range of health problems.
Symptoms
Symptoms of MCCD can vary widely, ranging from mild to severe. Some individuals may be asymptomatic (show no symptoms). When symptoms do occur, they can include:
Poor feeding
Vomiting
Lethargy
Seizures
Developmental delay
Hypotonia (low muscle tone)
Metabolic acidosis
Coma (in severe cases)
Causes
MCCD is caused by mutations in the MCCC1 or *MCCC2* genes. These genes provide instructions for making the two subunits of the MCC enzyme. Mutations in these genes result in a deficiency of the functional MCC enzyme. MCCD is inherited in an autosomal recessive pattern, meaning that both parents must carry a copy of the mutated gene for their child to be affected.
Medicine Used
Treatment for MCCD focuses on managing symptoms and preventing metabolic crises. There is no cure.
Dietary Management: A low-protein diet, especially limiting leucine intake, is crucial. Specialized medical formulas and foods may be prescribed.
L-Carnitine Supplementation: L-carnitine helps remove accumulated organic acids from the body.
Emergency Protocol: During illness or stress, a high-calorie, carbohydrate-rich diet is recommended to prevent metabolic decompensation. Intravenous fluids and glucose may be necessary during acute crises.
Other supplements Some doctors might recommend other supplements to help with specific symtoms
Is Communicable
No, MCCD is not communicable. It is a genetic disorder, not an infectious disease. It is passed down from parents to their children through genes.
Precautions
Dietary Adherence: Strict adherence to the prescribed low-protein diet is essential.
Emergency Plan: Have a written emergency plan detailing what to do during illness or stress.
Early Intervention: Early diagnosis and treatment are crucial for minimizing long-term complications.
Genetic Counseling: Genetic counseling is recommended for families with a history of MCCD.
Monitor: Routine monitoring of affected people is extremely important
How long does an outbreak last?
MCCD is not an infectious disease and does not have outbreaks. Individuals with MCCD have the condition throughout their lives. However, they may experience metabolic crises triggered by illness, stress, or dietary indiscretion. These crises can last for several hours to days and require prompt medical attention.
How is it diagnosed?
MCCD can be diagnosed through several methods:
Newborn Screening: Many states include MCCD in their newborn screening programs.
Urine Organic Acid Analysis: Elevated levels of specific organic acids in the urine (e.g., 3-methylcrotonylglycine) suggest MCCD.
Blood Acylcarnitine Profile: Elevated levels of certain acylcarnitines in the blood can indicate MCCD.
Enzyme Assay: Measuring the activity of the MCC enzyme in fibroblasts or leukocytes.
Genetic Testing: Identifying mutations in the MCCC1 or *MCCC2* genes.
Timeline of Symptoms
The onset and progression of symptoms can vary.
Newborn Period: Some infants may present with symptoms shortly after birth, such as poor feeding, vomiting, and lethargy. Newborn screening can detect the disorder before symptoms appear.
Infancy/Early Childhood: Other individuals may remain asymptomatic until later in infancy or early childhood when triggered by illness or increased protein intake. Developmental delays may become apparent during this time.
Adulthood: In some cases, individuals may remain asymptomatic throughout their lives or experience only mild symptoms that are often undiagnosed until adulthood.
Metabolic Crises: At any age, metabolic crises can occur, characterized by vomiting, lethargy, seizures, and coma.
Important Considerations
Lifelong Management: MCCD requires lifelong dietary management and monitoring.
Individual Variability: Symptoms and severity can vary significantly among individuals.
Early Diagnosis and Treatment: Early diagnosis and treatment are essential to prevent serious complications.
Education: Families and caregivers need to be educated about the condition, its management, and emergency protocols.
Support Groups: Support groups can provide valuable information and emotional support to families affected by MCCD.