Objective:To investigate the role of m.4435A>G and YARS2 c.572G>T(p.G191V)mutations in the development of essential hypertension.Methods:A hypertensive patient with m.4435A>G and YARS2 p.G191V mutations was identified from previously collected mitochondrial genome and exon sequencing data.Clinical data were collected,and a molecular genetic study was conducted in the proband and his family members.Peripheral venous blood was collected,and immortalized lymphocyte lines constructed.The mitochondrial transfer RNA(tRNA),mitochondrial protein,adenosine triphosphate(ATP),mitochondrial membrane potential(MMP),and reactive oxygen species(ROS)in the constructed lymphocyte cell lines were measured.Results:Mitochondrial genome sequencing showed that all maternal members carried a highly conserved m.4435A>G mutation.The m.4435A>G mutation might affect the secondary structure and folding free energy of mitochondrial tRNA and change its stability,which may influence the anticodon ring structure.Compared with the control group,the cell lines carrying m.4435A>G and YARS2 p.G191V mutations had decreased mitochondrial tRNA homeostasis,mitochondrial protein expression,ATP production and MMP levels,as well as increased ROS levels(all P<0.05).Conclusion:The YARS2 p.G191V mutation aggravates the changes in mitochondrial translation and mitochondrial function caused by m.4435A>G through affecting the steady-state level of mitochondrial tRNA and further leads to cell dysfunction,indicating that YARS2 p.G191V and m.4435A>G mutations have a synergistic effect in this family and jointly participate in the occurrence and development of essential hypertension.

OBJECTIVES: To explore the role of mitochondrial CYB 15024G>A mutation in the development of essential hypertension. METHODS: Mitochondrial genome sequences of hypertensive patients were obtained from previous studies. Clinical and genetic data of a hypertensive patient with mitochondrial CYB 15024G>A mutation and its pedigree were analyzed. Lymphocytes derived from patient and family members were transformed into immortalized lymphoblastoid cell lines, and the levels of adenosine triphosphate (ATP), mitochondrial membrane potential and intracellular reactive oxygen species (ROS) were detected. RESULTS: The penetrance of this essential hypertension family was 42.9%, and the age of onset was 46-68 years old. Mitochondrial genome sequencing results showed that all maternal members carried a highly conserved mitochondrial CYB 15024G>A mutation. This mutation could affect the free energy of mitochondrial CYB for secondary and tertiary structure and protein folding, thereby changing its structural stability and the structure of the electron transfer function area around the mutation site. Compared with the control, the cell line carrying the mitochondrial CYB 15024G>A mutation showed significantly decreased levels of mitochondrial CYB, ATP and mitochondrial membrane potential, and increased levels of ROS (P<0.01). CONCLUSIONS Mitochondrial CYB 15024G>A mutation may affect the structure of respiratory chain subunits and mitochondrial function, leading to cell dysfunction, which suggests that the mutation may play a synergistic role in essential hypertension.
Humans ; Middle Aged ; Aged ; Reactive Oxygen Species ; Essential Hypertension/genetics* ; Adenosine Triphosphate ; Cell Line ; Mutation

OBJECTIVE: To explore the feasibility of detecting maternal hereditary mitochondrial tRNA METHODS: We performed sequence analysis of mitochondrial DNA in blood samples from 2070 cases of maternal hereditary mitochondrial disease in the First Affiliated Hospital of Wenzhou Medical University, and identified 3 patients with m.15927G>A mutation.Buccal swabs and blood samples were obtained from the 3 patients (mutation group) and 3 normal volunteers (control group).After extracting whole genomic DNA from all the samples, the DNA concentration and purity were analyzed.The PCR products were subjected to dot blot hybridization, Southern blot hybridization, and DNA sequencing analysis to verify the feasibility of detecting m.15927G>A mutation using buccal swabs. RESULTS: There was no significant difference in DNA concentration extracted from buccal swabs and blood samples in either the mutation group or the control group ( CONCLUSIONS Buccal swabs collection accurate is an accurate and sensitive method for the detection of m.15927G>A mutation.
DNA, Mitochondrial/genetics* ; Humans ; Mitochondria ; Mutation ; RNA, Transfer ; Sequence Analysis, DNA

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

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 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

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 report on clinical, genetic and molecular characterization of two Chinese families with Leber's hereditary optic neuropathy.

METHODSOphthalmological examinations have revealed variable severity and age at onset of visual loss among the probands and other matrilineal relatives of both families. The entire mitochondrial genome of the two probands was amplified with PCR in 24 overlapping fragments using sets of oligonucleotide primers.

RESULTSThe ophthalmological examinations showed that penetrance was 12.5% and 30.0% respectively in the two families. Sequence analysis of the complete mitochondrial genomes in these pedigrees has identified unreported homoplasmic T8821G mutation in the ATPase 6 gene and distinct sets of polymorphisms belonging to haplogroups M10a. The T8821G mutation has occurred at the extremely conserved nucleotide (conventional position 99) of the ATPase6. Thus, this mutation may alter structural formation of ATPase6, thereby leading to failure in the synthesis of ATP involved in visual impairment.

CONCLUSIONAbove observations have suggested that the ATPase6 T8821G mutation may be involved in the pathogenesis of optic neuropathy in these families.

Adolescent ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; DNA, Mitochondrial ; genetics ; Female ; Humans ; Male ; Mitochondrial Proton-Translocating ATPases ; genetics ; Molecular Sequence Data ; Optic Atrophy, Hereditary, Leber ; enzymology ; genetics ; Pedigree ; Point Mutation ; Young Adult