Assignment of human gene encoding testis-specific lactate dehydrogenase C to chromosome 11, region p14.3-p15.5

Human lactate dehydrogenase-B processed pseudogene: nucleotide sequence analysis and assignment to the X-chromosome

Two human genomic clones containing the lactate dehydrogenase-B processed pseudogene were isolated from two patients deficient in lactate dehydrogenase-B isozyme. The sequences of 3,287 nucleotides, including the pseudogenes and its flanking regions, from both clones were found to be identical except for three differences in the pseudogenes. The sequences of 1,286 nucleotides from these two pseudogenes exhibited 93% homology with the cDNA sequence of the lactate dehydrogenase-B functional gene, and the pseudogene contained 75/76 base substitutions, 11/12 single-base deletions, and 5 single-base insertions. This pseudogene was mapped to the x-chromosome by dot-blot analysis using a probe for the pseudogene or its 5' flanking sequence.

A missense mutation found in human lactate dehydrogenase-B (H) variant gene

A human lactate dehydrogenase-B mutant gene was isolated from a genomic DNA library constructed from a patient with unstable LDH-B (heart) subunit. The nucleotide sequences of seven protein-coding exons were determined and a single nucleotide substitution of G by A at Arg codon CGC in exon 4 was found. This mutation results in an amino-acid replacement of a conserved arginine by histidine at the residue "173," which is involved in an anion-binding site at the P-axis of LDH subunits.

Molecular characterization of genetic mutation in human lactate dehydrogenase-A (M) deficiency

Human lactate dehydrogenase-A mutant gene was isolated from the genomic DNA library of a patient deficient in LDH-A (Muscle) subunit. The nucleotide sequences of seven protein-coding exons were determined and a deletion of 20 base-pairs in exon 6 was found. This mutation results in a frame-shift translation and premature termination. The predicted incomplete LDH-A (M) subunit containing only 259 instead of 331 amino acids appears to be degraded rapidly, since no protein was detected immunologically (Maekawa et al., Am J Hum Genet 39:232-238, 1986). In addition, three synonymous (silent) substitutions, A to C, T to C, and G to A, were observed at codons 115, 160 and 172, respectively, in this LDH-A mutant gene.

Regional localization of the sperm-specific lactate dehydrogenase, LDHC, gene on human chromosome 11

A cDNA clone complementary to the mRNA encoding the sperm-specific lactate dehydrogenase, LDHC, has been used to map the LDHC locus to the short arm of human chromosome 11. In situ hybridization data and analysis of mouse/human somatic cell hybrids carrying deletions of human chromosome 11 suggest that the gene is localized at p15.3-p15.5 close to the LDHA gene.