Document Detail

Cobalamin C defect: natural history, pathophysiology, and treatment.
MedLine Citation:
PMID:  20632110     Owner:  NLM     Status:  In-Data-Review    
Cobalamin C (Cbl-C) defect is the most common inborn cobalamin metabolism error; it causes impaired conversion of dietary vitamin B12 into its two metabolically active forms, methylcobalamin and adenosylcobalamin. Cbl-C defect causes the accumulation of methylmalonic acid and homocysteine and decreased methionine synthesis. The gene responsible for the Cbl-C defect has been recently identified, and more than 40 mutations have been reported. MMACHC gene is located on chromosome 1p and catalyzes the reductive decyanation of CNCbl. Cbl-C patients present with a heterogeneous clinical picture and, based on their age at onset, can be categorized into two distinct clinical forms. Early-onset patients, presenting symptoms within the first year, show a multisystem disease with severe neurological, ocular, haematological, renal, gastrointestinal, cardiac, and pulmonary manifestations. Late-onset patients present a milder clinical phenotype with acute or slowly progressive neurological symptoms and behavioral disturbances. To improve clinical course and metabolic abnormalities, treatment of Cbl-C defect usually consists of a combined approach that utilizes vitamin B12 to increase intracellular cobalamin and to maximize deficient enzyme activities, betaine to provide a substrate for the conversion of homocysteine into methionine through betaine-homocysteine methyltransferase, and folic acid to enhance remethylation pathway. No proven efficacy has been demonstrated for carnitine and dietary protein restriction. Despite these measures, the long-term follow-up is unsatisfactory especially in patients with early onset, with frequent progression of neurological and ocular impairment. The unfavorable outcome suggests that better understanding of the pathophysiology of the disease is needed to improve treatment protocols and to develop new therapeutic approaches.
Diego Martinelli; Federica Deodato; Carlo Dionisi-Vici
Publication Detail:
Type:  Journal Article     Date:  2010-07-15
Journal Detail:
Title:  Journal of inherited metabolic disease     Volume:  34     ISSN:  1573-2665     ISO Abbreviation:  J. Inherit. Metab. Dis.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7910918     Medline TA:  J Inherit Metab Dis     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  127-35     Citation Subset:  IM    
Division of Metabolism, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165, Rome, Italy.
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