Methylmalonic Acidemia with Homocystinuria (Cbl C, D, F)



Methylmalonic acidemia with homocystinuria (Cbl C, D, F) is one type of methylmalonic acidemia. Individuals with this form of methylmalonic acidemia have trouble producing certain cobalamin enzymes, which causes harmful levels of homocysteine and methylmalonic acid to build up in the body. Signs of methylmalonic acidemia with homocystinuria could begin anywhere between the first few days of life and 14 years of age. Children with Cbl C usually show symptoms between the first few days and the first month of life. Children with Cbl D deficiency do not show signs until later in childhood. Early signs of Cbl C, D, F include delayed growth, small head size, skin rash, vomiting, poor appetite, diarrhea, fever, sleeping longer or more often, tiredness, and weak muscle tone. Many of these signs may occur when a baby eats foods that the body cannot break down.

Condition Type:



Methylmalonic acidemia is estimated to affect 1 out of every 50,000 to 100,000 individuals. However, methylmalonic acidemia with homocystinuria (Cbl C, D, F) is only one form of methylmalonic acidemia, and the exact number of people affected by this specific form is unknown.

More Information for Parents:
Also known as:
  • Cbl C, D, F
  • Type 2 vitamin B12 metabolic defect
  • Methyltetrahydrofolate methyltransferase deficiency
  • Combined deficiency of methylmalonyl CoA mutase and homocystinuria
  • CblC
  • CblD
  • CblF

Core Conditions