Objective To investigate the correlation between the variations of mitochondrial gene ATP6 and type 2 diabetes mellitus ( T2DM ) and chronic complications. Methods Genomic DNA were extracted from 254 T2DM patients and 165 age-matched controls. After amplification of ATP6 by PCR and direct sequencing, all sequences were compared with the reference sequence (rCRS) to find out the variations. Bioinformatics and statistic method were used to analyze these variations. Results Many variations were detected respectively in T2DM patients and controls, a part of them only appeared in T2DM patients in low frequency, which has not been reported previously. Most of these variations are located in thethird and forth transmembrane helix of ATP synthase subunit 6 (ATPase6). Interestingly, these variationsalmost were detected in the non-obese T2DM patients with hypotension, including G8557A, A8563G,T8594C, C8609T, A8689G, G8998A and G9139A. Conclusions There were many variations in geneATP6 and must of them are mitochondrial SNP, while variations A8689G, T8825C, G8920A, G8998A andG9139A may be mild mutations which my increase the susceptibility of T2DM. G8557A, A8563G,T8594C, C8609T, A8689G, G8998A and G9139A may be associated with the biogenetics diseases suchdiabetes and hypertension.

Objective To investigate the clinical application of multiplex allele-specific PCR assays for simultaneous detection of the mitochondrial 12S rRNA A1555G and C1494T mutations associated with aminoglycoside-induced hearing impairment.Methods Three standard plasmids of different genotypes (wild-type, A1555G mutant and C1494T mutant) were constructed for templates and allele-specific primers aiming directly at wild-type and mutant of mitochondrial DNA nt1555 and nt1494 were designed for developing a multiplex allele-specific PCR technique to detect the A1555G and C1494T mutations.Then the method was applied to clinical screening of 138 non-syndromic hearing loss subjects and confirmed by DNA sequencing.Results Multiplex allele-specific PCR was successfully applied to the detection of A1555G and C1494T mutations in a cohort of 138 Han Chinese genetically unrelated hearing-loss subjects.Finally, 11(7.97%) unrelated affected subjects harbored the A1555G and C1494T mutations in the 12S rRNA gene(10 cases for A1555G and 1 cases for C1494T), which was well consistent with results of DNA sequencing [7.97%(11/138), Kappa=1.000, P＜0.01].Conclusion This study indicates that the multiplex allele-specific PCR assay is useful, convenient and reliable in the detection of the A1555G and C1494T mutations, which could identify the subjects at risk and effectively prevent of aminoglycoside-induced hearing loss.

A high proportion of modified nucleotides has been found in mitochondrial tRNA. Such modification can promote accurate folding of tRNA and its stability, while unmodified mitochondrial tRNA may fold into various 2D-structures with impaired functions. Therefore, modification of mitochondrial tRNA is closely related to mitochondrial diseases. Particularly, positions 9, 34, 37, 54 and 55 of the mitochondrial tRNA are critical for such modification. Mutations at these positions are important cause for mitochondrial dysfunction and have been associated with various mitochondrial diseases.
DNA, Mitochondrial ; chemistry ; genetics ; Humans ; Mitochondrial Diseases ; genetics ; Mutation ; Nucleic Acid Conformation ; RNA, Transfer ; chemistry ; genetics

Mitochondrial tRNAgene mutation is closely related to acoustic nerve deafness. Some mutations can affect the structure and transcriptional processing of tRNA, for instance m.7444G>A mutation in tRNAprecursor 3' side, m.7472 insC as well as m.7511T>C mutations in the stem and ring of tRNA, may influence tRNAstability, thus affect the synthesis of mitochondrial peptides, reduce the production of ATP and cause deafness. This article focuses on mitochondrial tRNAgene mutations as well as the mechanism underlying hearing loss.
Amino Acid Sequence ; Base Sequence ; Genetic Predisposition to Disease ; genetics ; Hearing Loss ; genetics ; Humans ; Mitochondrial Proteins ; biosynthesis ; genetics ; Mutation ; Nucleic Acid Conformation ; RNA ; chemistry ; genetics ; RNA, Transfer, Ser ; chemistry ; genetics

OBJECTIVETo investigate the role of MT-ND1 m.3635G>A mutation in the pathogenesis of Leber's hereditary optic neuropathy (LHON).

METHODSBiochemical characteristics including the activity of complex Ⅰ, ATP production and oxygen consumption rate among lymphoblastoid cell lines derived from 3 carriers, 3 affected matrilineal relatives of the families and 3 controls were compared.

RESULTSComparison of mitochondrial functions in lymphoblastoid cell lines of the carriers, patients and controls showed a 51.0% decrease in the activity of complex Ⅰ in patients compared with controls (P<0.05). The m.3635G>A mutation has resulted in decreased efficiency of ATP synthesis (P<0.05). Comparison of oxygen consumption rate showed that the basal OCR (P<0.05), ATP-linked OCR (P<0.05) and the maximum OCR (P<0.05) have all reduced to some extent compared with the controls.

CONCLUSIONThese results showed that m.3635G>A, as a LHON-associated mutation, can lead to mitochondrial dysfunction.

Adenosine Triphosphate ; genetics ; Asian Continental Ancestry Group ; genetics ; Female ; Humans ; Male ; Mitochondria ; genetics ; Mutation ; genetics ; NADH Dehydrogenase ; genetics ; Optic Atrophy, Hereditary, Leber ; genetics ; Pedigree

Inherited retinal diseases (IRDs), including retinitis pigmentosa, Usher syndrome, Cone-Rod degenerations, inherited macular dystrophy, Leber's congenital amaurosis, Leber's hereditary optic neuropathy are the most common and severe types of hereditary ocular diseases. So far more than 200 pathogenic genes have been identified. With the growing knowledge of the genetics and mechanisms of IRDs, a number of gene therapeutic strategies have been developed in the laboratory or even entered clinical trials. Here the progress of IRD research on the pathogenic genes and therapeutic strategies, particularly gene therapy, are reviewed.
Biomedical Research ; methods ; trends ; Clinical Trials as Topic ; Genetic Predisposition to Disease ; genetics ; Genetic Therapy ; methods ; trends ; Humans ; Mutation ; Retinal Diseases ; genetics ; therapy ; Treatment Outcome

OBJECTIVETo study the relationship between mitochondrial DNA (mtDNA) mutations and hypertension.

METHODSClinical data of two pedigrees with maternally transmitted hypertension was collected. Whole mtDNA sequence was analyzed.

RESULTSThe family members on the maternal side presented with various levels of hypertension, with the onset age ranging from 44 to 55 years old. Analysis of the mtDNA sequence of the two families members showed all patients have carried a matrilineal 4329C> G mutation of the tRNA(Ile) and tRNA(Gln) genes. The same mutation was not found in 366 healthy controls. The 4329C site of mtDNA is highly conserved across species, and has been associated with the fidelity of amino acid accept arm of the tRNAs, as well as functionality and stability in the formation of tRNAs.

CONCLUSIONThe 4329C> G point mutation in tRNA(Ile) and tRNA(Gln) probably has contributed to the pathogenesis of hypertension, possibly in association with other modifying factors.

Adult ; Base Sequence ; DNA Mutational Analysis ; DNA, Mitochondrial ; chemistry ; genetics ; Family Health ; Female ; Genetic Predisposition to Disease ; genetics ; Humans ; Hypertension ; genetics ; Male ; Middle Aged ; Molecular Sequence Data ; Pedigree ; Point Mutation ; RNA, Transfer, Gln ; genetics ; RNA, Transfer, Ile ; genetics ; Sequence Homology, Amino Acid

OBJECTIVETo report on the clinical, genetic and molecular characteristics of three ethnic Han Chinese families affected with Leber's hereditary optic neuropathy (LHON).

METHODSThe three families were all diagnosed with LHON. Ophthalmologic examinations were conducted on the probands . The ND1, ND4 and ND6 genes of the mitochondrial DNA (mtDNA) were amplified with PCR respectively for the screening of three primary mutations G3460A, G11778A and T14484C. The entire mtDNA of the probands were also amplified by PCR.

RESULTSAnalysis of mtDNA in the three pedigrees has failed to find the presence of the three LHON associated mutations but presence of a homoplastic ND1 T3866C mutation in all probands and their matrilineal relatives . The probands had different levels of visual impairment. The penetrance in the three families has been calculated as 12.5%, 11.1% and 33.3%, respectively. The T3866C mutation has resulted in replacement of isoleucine at position 187 with theronine. The isoleucine at position 187 is located at one of the transmembrane domains of ND1 polypeptide.

CONCLUSIONAbove results have suggested that the ND1 T3866C mutation might have been involved in the pathogenesis of LHON in the three Chinese families studied.

Adolescent ; Asian Continental Ancestry Group ; ethnology ; genetics ; Base Sequence ; Child ; Female ; Humans ; Male ; Mitochondria ; genetics ; Molecular Sequence Data ; NADH Dehydrogenase ; genetics ; Optic Atrophy, Hereditary, Leber ; ethnology ; genetics ; Pedigree ; Point Mutation

OBJECTIVETo identify secondary mutations associated with deafness in a Chinese family affected with deafness.

METHODSThe family has been subjected to clinical and molecular analyses, in addition with measurement of reactive oxygen species and doubling time after establishment of immortalized lymphocyte cell lines.

RESULTSThe results showed that the hearing loss level and audiometric configuration were discrepant among the family members with maternally transmitted hearing loss. The penetrance of hearing loss in this family was respectively 66.7% and 44.4% when aminoglycoside-induced hearing loss was included or excluded. Analysis of whole mitochondrial genome has found 33 variants as previously reported polymorphisms, except for a 12s rRNA A1555G mutation and a tRNA(Thr)T15943C mutation. Haplotype evolutionary tree has verified that this family belonged to East-Asian haplogroup F. 15943 position was located on the T-stem of the tRNA(Thr), which has destroyed the extremely conserved T-A base pair when T changed to C at this position. However, functional experiments indicated that the population doubling time in special galactose and glucose were longer, whilst the level of reactive oxygen species has increased. Compared with the control cell line groups and a family only carrying the 12s rRNA A1555G mutation, all of the three groups belonged to the same haplogroup.

CONCLUSIONMitochondrial tRNA(Thr)T15943C mutation may act as a potential modifying factor and interact with 12s rRNA A1555G mutation, and thereby enhance the penetrance and expression of deafness.

Adolescent ; Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; Child, Preschool ; China ; DNA, Mitochondrial ; genetics ; Deafness ; genetics ; Female ; Humans ; Male ; Middle Aged ; Molecular Sequence Data ; Pedigree ; Phenotype ; Point Mutation ; RNA, Ribosomal ; genetics ; RNA, Transfer, Thr ; genetics ; Young Adult

OBJECTIVETo investigate the correlation between nonsyndromic deafness and mitochondrial 12s rRNA A839G mutation.

METHODSAccording to the clinical manifestations of mitochondrial DNA sequencing and analysis to find and determine family containing mitochondrial 12s rRNA A839G mutation. Harvested its family members blood and transferred their lymphocytes into lymphoblastoid cell lines, followed by cells cultured, cell doubling experiment, susceptibility testing, cellular oxygen consumption rate experiment, ROS and mitochondrial membrane potential experimental tests were progressed to explore the correlation between the A839G mutation and nonsyndromic deafness.

RESULTSThe mitochondrial 12s rRNA A839G mutation pedigrees were determined through the full sequence detections of the Mitochondrial DNA, further phylogenetic analysis showed that 839 point conservative index (CI) up to 78.6%; in RPMI-galactose medium containing A839G gene mutant cell line, the doubling time was significantly longer than the control group, and the difference was significant (P = 0.033). The effect to cell lines containing the A839G mutation of aminoglycoside drugs was not obvious. When compared with the control group, cell lines containing the A839G mutation significantly reduced cellular oxygen consumption rate(P = 0.033); compared with the control group, the ROS levels of cell lines containing the A839G mutation appeared more substantial elevated with significan difference (P < 0.01). The mitochondrial membrane potential of cells of experimental group was significantly reduced than the control group.

CONCLUSIONThe present study proved that the mitochondria 12s rRNA A839G mutations affect the function of the mitochondrial respiratory chain at the cell level, which might reduce the growth rate of the mutant cell lines, result in hearing.

Aminoglycosides ; Cell Line ; DNA, Mitochondrial ; Deafness ; genetics ; Galactose ; Hearing Tests ; Mitochondria ; Mutation ; Pedigree ; Phylogeny ; RNA, Ribosomal ; genetics