What Your Test Results Mean:

Test results indicate that you are a carrier of 3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency, MCCC2-related. Carriers are not expected to show symptoms. You and your partner would both have to be carriers of 3-MCC deficiency for there to be an increased chance to have a child with symptoms; this is known as autosomal recessive inheritance. Carrier testing of your partner or donor is recommended in addition to consultation with a genetic counselor for a more detailed risk assessment.

Since this is an inherited gene change, this information may be helpful to share with family members as it may impact their family planning.

Disease Explained:

3-MCC deficiency is an inherited disorder in which the body is unable to process proteins containing a particular building block (amino acid) called leucine. Symptoms typically present in infancy or early childhood and consist of feeding difficulties, recurrent episodes of vomiting and diarrhea, excessive tiredness (lethargy), and weak muscle tone (hypotonia). If untreated, this disorder can lead to delayed development, seizures, and coma. The severity of these symptoms ranges from mild to life-threatening, and some people with gene variants that cause 3-MCC deficiency never experience any signs or symptoms of the condition.

Prognosis:

Most individuals diagnosed with 3-MCC deficiency can live healthy lives and never need any special treatment. For individuals who do develop symptoms, prognosis is good with early and careful treatment. If left untreated, babies can develop breathing problems, seizures, liver failure, and coma.

Treatment:

Treatment for 3-MCC deficiency includes avoiding fasting, a low-protein diet, and appropriate supplements (L-carnitine).