Eighteen‐year follow‐up of a patient with cobalamin F disease (cblF): Report and review

Cobalamin F disease (cblF) is a rare disorder of intracellular cobalamin metabolism resulting in failure to thrive, recurrent stomatitis, skin rash, megaloblastic anemia, hypotonia, seizures, and intellectual disability. Data on long-term outcomes are not available. We report on the outcome of a patient with cblF disease with a frameshift mutation in the LMBRD1 gene after 18 years of intramuscular hydroxycobalamin treatment.