Journal Article

Human Methionine Synthase: cDNA Cloning and Identification of Mutations in Patients of the cblG Complementation Group of Folate/Cobalamin Disorders

D. Leclerc, E. Campeau, P. Goyette, C. E. Adjalla, B. Christensen, M. Ross, P. Eydoux, D. S. Rosenblatt, R. Rozen and R. A. Gravel

in Human Molecular Genetics

Volume 5, issue 12, pages 1867-1874
Published in print December 1996 | ISSN: 0964-6906
e-ISSN: 1460-2083 | DOI:

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Methionine synthase catalyzes the remethylation of homocysteine to methionine in a methylcobalamin-dependent reaction. We used specific regions of homology within the methionine synthase sequences of several lower organisms to clone a human methionine synthase cDNA by a combination of RT-PCR and inverse PCR. The enzyme is 1265 amino acids in length and contains the seven residue structure-based sequence fingerprint identified for cobalamin-containing enzymes. The gene was localized to chromosome 1q43 by the FISH technique. We have identified one missense mutation and a 3 bp deletion in patients of the cbIG complementation group of inherited homocysteine/folate disorders by SSCP and sequence analysis, as well as an amino acid substitution present in high frequency in the general population. We discuss the possibility that a mild deficiency of methionine synthase activity could be associated with mild hyperhomocysteinemia, a risk factor for cardiovascular disease and possibly neural tube defects.

Journal Article.  3862 words.  Illustrated.

Subjects: Genetics and Genomics