Journal Article

Molecular Basis for Methionine Synthase Reductase Deficiency in Patients Belonging to the cblE Complementation Group of Disorders in Folate/Cobalamin Metabolism

A. Wilson, D. Leclerc, D.S. Rosenblatt and R.A. Gravel

in Human Molecular Genetics

Volume 8, issue 11, pages 2009-2016
Published in print October 1999 | ISSN: 0964-6906
Published online October 1999 | e-ISSN: 1460-2083 | DOI: https://dx.doi.org/10.1093/hmg/8.11.2009
Molecular Basis for Methionine Synthase Reductase Deficiency in Patients Belonging to the cblE Complementation Group of Disorders in Folate/Cobalamin Metabolism

Show Summary Details

Preview

Methionine synthase reductase (MSR) deficiency is an autosomal recessive disorder of folate/cobalamin metabolism leading to hyperhomocysteinemia, hypo-methioninemia and megaloblastic anemia. Deficiency in MSR activity occurs as the result of a defect in the MSR enzyme, which is required for the reductive activation of methionine synthase (MS). MS itself is responsible for the folate/cobalamin-dependent conversion of homo-cysteine to methionine. We have recently cloned the cDNA corresponding to the MSR protein, a novel member of the ferredoxin-NADP+ reductase (FNR) family of electron transferases. We have used RT-PCR, heteroduplex, single-strand conformation polymorphism (SSCP) and DNA sequence analyses to reveal 11 mutations in eight patients from seven families belonging to the cblE complementation group of patients of cobalamin metabolism that is defective in the MSR protein. The mutations include splicing defects leading to large insertions or deletions, as well as a number of smaller deletions and point mutations. Apart from an intronic substitution found in two unrelated patients, the mutations appear singular among individuals. Of the eleven, three are nonsense mutations, allowing for the identification oftwo patients for whom little if any MSR protein should be produced. The remaining eight involve point mutations or in-frame disruptions of the coding sequence and are distributed throughout the coding region, including proposed FMN, FAD and NADPH binding sites. These data demonstrate a unique requirement for MSR in the reductive activation of MS.

Journal Article.  5547 words.  Illustrated.

Subjects: Genetics and Genomics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content. subscribe or login to access all content.