3-Methylcrotonyl-CoA Carboxylase Deficiency (3MCC)
Description
3-Methylcrotonyl-CoA Carboxylase Deficiency (3MCC) is a rare inherited metabolic disorder that affects the body‘s ability to break down certain amino acids, particularly leucine. This leads to a buildup of harmful substances in the body, causing a range of symptoms, particularly in newborns and infants. Learn more about 3MCC, including its signs, causes, diagnosis, and management strategies.
Genes Involved
3MCC is caused by mutations in one of two genes:
- MCCC1: This gene provides instructions for making the alpha subunit of the 3-methylcrotonyl-CoA carboxylase enzyme.
- MCCC2: This gene provides instructions for making the beta subunit of the 3-methylcrotonyl-CoA carboxylase enzyme.
Recognizing the Signs and Symptoms
Symptoms of 3MCC can vary depending on the severity of the deficiency and can manifest shortly after birth or later in life. Common signs include:
- Vomiting and poor feeding
- Lethargy and weakness
- Seizures
- Delayed development
- Metabolic acidosis (build-up of acid in the blood)
- Increased levels of 3-hydroxyisovaleric acid in the urine
- Unusual odor in the urine, sweat, and breath
- Failure to thrive
In some cases, 3MCC can also lead to neurological problems, such as intellectual disability, cerebral palsy, and vision or hearing impairments.
Causes
3MCC is an autosomal recessive disorder, meaning that both parents must carry a copy of the mutated gene for their child to be affected. If both parents are carriers, there is a 25% chance with each pregnancy that their child will inherit the disorder.
Inheritance/recurrence risk
3MCC is inherited in an autosomal recessive pattern. This means that both parents must carry a copy of the mutated gene for their child to inherit the disorder. If both parents are carriers, there is a 25% chance with each pregnancy that their child will inherit the disorder.
- Carrier testing: If you have a family history of 3MCC or are concerned about the risk, genetic testing can help determine if you are a carrier.
- Prenatal testing: If you are at risk of having a child with 3MCC, prenatal testing can be done to check for the genetic mutation.
