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Methylmalonic acidemia with homocystinuria type cblF

Synonym(s) CblF defect
Cobalamin F defect
Combined defect in adenosylcobalamin and methylcobalamin synthesis, type cblF
Lysosomal membrane cobalamin transporter deficiency
Methylmalonic aciduria with homocystinuria, type cblF
Prevalence <1 / 1 000 000
Inheritance Autosomal recessive
Age of onset Childhood
  • E72.1
MeSH -
MedDRA -


Disease definition

cblF type methylmalonic acidemia with homocystinuria is a form of methylmalonic acidemia with homocystinuria (see this term), an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, lethargy, failure to thrive, developmental delay, intellectual deficit and seizures.


To date, 15 cases have been reported.

Clinical description

cblF type methylmalonic acidemia with homocystinuria has a variable age of onset (from birth to 11 years of age) and manifestations also vary and can include development delay, feeding difficulties, signs of megaloblastic anemia (pallor, fatigue, anorexia), hypotonia, stomatitis and skin rashes.


The disorder is caused by mutations in the LMBRD1 gene (6q13) and is transmitted in an autosomal recessive manner.

Expert reviewer(s)

  • Dr David WATKINS

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Detailed information

Clinical practice guidelines
Article for general public
Clinical genetics review
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