[Molecular clonging of the human dimethyglycine dehydrogenase-like gene (DMGDHL1) from the sarcosinemia critical region at 9q34].

Through the analysis of EST database, we obtained one human EST (GenBank: H28856) which showed significant similarity with the partial coding sequence of rat dimethylglycine dehydrogenase gene. This EST was mapped to 9q34 due to 95.6% identity with one genomic sequence (GenBank: AC002295). A pair of primers (HRP-1/HRP-2) designed on the sequence of the EST were coupled with the primers (lambda gt10-5/lambda gt10-3) on the vector flanking cloning site respectively to amplify the 5' and 3' cDNA beyond the EST. New primers designed based on novel cDNA sequence overlapped with the sequence within EST H28856 were used for amplification with lambda gt10-5 and lambda gt10-3 by the similar way as above untill a complete ORF was obtained. Finally, a 1,970 bp sequence (termed as dimethylglycine dehydrogenase like gene isoform I, DMGDHL1a) containing a 1,428 bp complete coding sequence from the live cDNA library and 1,475 bp sequence (isoform II, termed as DMGDHL1b) containing a 1,296 bp complete coding sequence from the fetas live cDNA library were obtained. Fourteen exons were identified in isoform I and the first nine exons of isoform II which shared with isoform I could be determined too. The last 105 bp cDNA sequence of isoform II could not be found in the public database, indicating a very large intron (> 123 kb) existed between exon 9 and exon 10 of isoform II. DMGDHL1 showed highly homology on both cDNA and amino acid level with rat dimethylglycine dehydrogenase (60% identity in 135 bp and 35% identity in 436 residues respectively). It was reported that human sarcosinemia gene was mapped at 9q34. Therefore it could be a good candidate gene for the sarcosinemia.