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Isolated 3-methylcrotonyl-CoA carboxylase deficiency : evidence for an allele-specific dominant negative effect and responsiveness to biotin therapy

Baumgartner, Matthias R. and Dantas, M. Fernanda and Suormala, Terttu and Almashanu, Shlomo and Giunta, Cecilia and Friebel, Dolores and Gebhardt, Boris and Fowler, Brian and Hoffmann, Georg F. and Baumgartner, E. Regula and Valle, David. (2004) Isolated 3-methylcrotonyl-CoA carboxylase deficiency : evidence for an allele-specific dominant negative effect and responsiveness to biotin therapy. American journal of human genetics, Vol. 75, H. 5. pp. 790-800.

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Official URL: http://edoc.unibas.ch/dok/A5253386

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Abstract

Deficiency of 3-methylcrotonyl-CoA carboxylase (MCC) results in elevated excretion of 3-methylcrotonylglycine (3-MCG) and 3-hydroxyisovaleric acid (3-HIVA). MCC is a heteromeric mitochondrial enzyme comprising biotin-containing alpha subunits and smaller beta subunits, encoded by MCCA and MCCB, respectively. Mutations in these genes cause isolated MCC deficiency, an autosomal recessive disorder with a variable phenotype that ranges from severe neonatal to asymptomatic adult forms. No reported patients have responded to biotin therapy. Here, we describe two patients with a biochemical and, in one case, clinical phenotype of MCC deficiency, both of whom were responsive to biotin. The first patient presented at 3 months with seizures and progressive psychomotor retardation. Metabolic investigation at 2 years revealed elevated excretion of 3-MCG and 3-HIVA, suggesting MCC deficiency. High-dose biotin therapy was associated with a dramatic reduction in seizures, normalization of the electroencephalogram, and correction of the organic aciduria, within 4 weeks. MCC activity in fibroblasts was 25% of normal levels. The second patient, a newborn detected by tandem-mass-spectrometry newborn screening, displayed the same biochemical phenotype and remained asymptomatic with biotin up to the age of 18 months. In both patients, sequence analysis of the complete open reading frames of MCCA and MCCB revealed heterozygosity for MCCA-R385S and for the known polymorphic variant MCCA-P464H but revealed no other coding alterations. MCCA-R385S is unusual, in that it has a normal amount of MCC alpha protein but confers no MCC activity. We show that MCCA-R385S, but not other MCCA missense alleles, reduces the MCC activity of cotransfected MCCA-wild-type allele. Our results suggest that MCCA-R385S is a dominant negative allele and is biotin responsive in vivo.
Faculties and Departments:03 Faculty of Medicine > Bereich Kinder- und Jugendheilkunde (Klinik) > Ehemalige Einheiten P├Ądiatrie (UKBB) > Labor (Fowler)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Kinder- und Jugendheilkunde (Klinik) > Ehemalige Einheiten P├Ądiatrie (UKBB) > Labor (Fowler)
UniBasel Contributors:Fowler, Brian
Item Type:Article, refereed
Article Subtype:Book Review
Bibsysno:Link to catalogue
Publisher:Univ. of Chicago Press
ISSN:0002-9297
Note:Publication type according to Uni Basel Research Database: Journal item
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Last Modified:22 Mar 2012 14:24
Deposited On:22 Mar 2012 13:37

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