101
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Louet JF, Smith SB, Gautier JF, Molokhia M, Virally ML, Kevorkian JP, Guillausseau PJ, Vexiau P, Charpentier G, German MS, Vaisse C, Urbanek M, Mauvais-Jarvis F. Gender and neurogenin3 influence the pathogenesis of ketosis-prone diabetes. Diabetes Obes Metab 2008; 10:912-20. [PMID: 18093211 DOI: 10.1111/j.1463-1326.2007.00830.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Ketosis-prone diabetes (KPD) is a phenotypically defined form of diabetes characterized by male predominance and severe insulin deficiency. Neurogenin3 (NGN3) is a proendocrine gene, which is essential for the fate of pancreatic beta cells. Mice lacking ngn3 develop early insulin-deficient diabetes. Thus, we hypothesized that gender and variants in NGN3 could predispose to KPD. We have studied clinical and metabolic parameters according to gender in patients with KPD (n = 152) and common type 2 diabetes (T2DM) (n = 167). We have sequenced NGN3 in KPD patients and screened gene variants in T2DM and controls (n = 232). In KPD, male gender was associated with a more pronounced decrease in beta-cell insulin secretory reserve, assessed by fasting C-peptide [mean (ng/ml) +/- s.d., M: 1.1 +/- 0.6, F: 1.5 +/- 0.9; p = 0.02] and glucagon-stimulated C-peptide [mean (ng/ml) +/- s.d., M: 2.2 +/- 1.1, F: 3.1 +/- 1.7; p = 0.03]. The rare affected females were in an anovulatory state. We found two new variants in the promoter [-3812T/C (af: 2%) and -3642T/C (af: 1%)], two new coding variants [S171T (af: 1%) and A185S (af: 1%)] and the variant already described [S199F (af: 69%)]. These variants were not associated with diabetes. Clinical investigation revealed an association between 199F and hyperglycaemia assessed by glycated haemoglobin [HbA1c (%, +/-s.d.) S199: 12.6 +/- 1.6, S199F: 12.4 +/- 1.4 and 199F: 14.1 +/- 2.2; p = 0.01]. In vitro, the P171T, A185S and S199F variants did not reveal major functional alteration in the activation of NGN3 target genes. In conclusion, male gender, anovulatory state in females and NGN3 variations may influence the pathogenesis of KPD in West Africans. This has therapeutic implications for potential tailored pharmacological intervention in this population.
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Affiliation(s)
- J-F Louet
- Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
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102
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Sasarman F, Antonicka H, Shoubridge EA. The A3243G tRNALeu(UUR) MELAS mutation causes amino acid misincorporation and a combined respiratory chain assembly defect partially suppressed by overexpression of EFTu and EFG2. Hum Mol Genet 2008; 17:3697-707. [DOI: 10.1093/hmg/ddn265] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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103
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Abstract
There are two major forms of diabetes: type 1 and type 2. However, monogenic diabetes, associated with severe beta-cell dysfunction or with severe resistance to insulin action, is diagnosed with increasing frequency by genetic testing. The list of such forms of diabetes includes MODY, mitochondrial diabetes, permanent neonatal diabetes (PNDM) and transient neonatal diabetes, familial lipodystrophies and some others. These rare forms constitute probably at least a few per cent of all diabetes cases seen in diabetic clinics. The identification of the molecular background of specific forms of diabetes gives new insight into the underlying aetiology. This knowledge helps to optimize treatment in specific clinical situations. The proper differential diagnosis also helps to predict the progress of diabetes in affected individuals and defines the prognosis in the family. For example, in patients with MODY2 because of glucokinase mutations who have very mild diabetes characterized by modest fasting, hyperglycaemia diet is frequently sufficient. Some other forms of monogenic diabetes associated with impaired function of the beta-cell, such as MODY3 and PNDM linked to mutations in Kir6.2 and SUR1 genes, can be successfully managed by sulphonylurea agents. Although the examples of pharmacogenetics seem to be less spectacular in rare syndromes of insulin resistance, those patients can also benefit from genetic testing. In this paper, the aetiology of some monogenic diabetes forms is reviewed together with the clinical aspects of management of the affected individuals.
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Affiliation(s)
- Maciej T Malecki
- Department of Metabolic Diseases, Medical College, Jagiellonian University, Krakow, Poland. ;
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104
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Takahashi Y, Iida K, Takeno R, Kitazawa R, Kitazawa S, Kitamura H, Fujioka Y, Yamada H, Kanda F, Ohta S, Nishimaki K, Fujimoto M, Kondo T, Iguchi G, Takahashi K, Kaji H, Okimura Y, Chihara K. Hepatic failure and enhanced oxidative stress in mitochondrial diabetes. Endocr J 2008; 55:509-14. [PMID: 18445996 DOI: 10.1507/endocrj.k07e-091] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mitochondrial diabetes is characterized by diabetes and hearing loss in maternal transmission with a heteroplasmic A3243G mutation in the mitochondrial gene. In patients with the mutation, it has been reported that hepatic involvement is rarely observed. We demonstrated a case of hypertrophic cardiomyopathy and hepatic failure with mitochondrial diabetes. To clarify the pathogenesis we analyzed the mitochondrial ultrastructure in the myocytes, the reactive oxygen species (ROS) production in the liver and the status of heteroplasmy of the mitochondrial A3243G mutation in the organs involved. In cardiomyocytes and skeletal muscle, electron microscopic analysis demonstrated typical morphological mitochondrial abnormalities. Immunohistochemical analysis demonstrated enhanced ROS production associated with marked steatosis in the liver, which is often associated with mitochondrial dysfunction. Analysis of the A3243G mutation revealed a substantial ratio of heteroplasmy in these organs including the liver. The presence of steatosis and enhanced oxidative stress in the liver suggested that hepatic failure was associated with mitochondrial dysfunction.
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Affiliation(s)
- Yutaka Takahashi
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
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105
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Rath PP, Jenkins S, Michaelides M, Smith A, Sweeney MG, Davis MB, Fitzke FW, Bird AC. Characterisation of the macular dystrophy in patients with the A3243G mitochondrial DNA point mutation with fundus autofluorescence. Br J Ophthalmol 2008; 92:623-9. [PMID: 18441172 PMCID: PMC2569141 DOI: 10.1136/bjo.2007.131177] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
INTRODUCTION The mitochondrial DNA A3243G point mutation is associated with a wide variety of systemic manifestations including a macular dystrophy. The characteristics of fundus autofluorescence (AF) in these patients are distinctive and have not been previously described. METHODS A complete history and ophthalmic examination, including fundus photography and autofluorescence imaging, was performed on twelve probands harbouring the A3243G point mutation. RESULTS Four patients had diabetes, 10/12 hearing loss, and 7/12 were visually symptomatic. A positive family history was present in 5/12. Fundus findings consisted of two primary phenotypes: discontinuous circumferentially oriented perifoveal atrophy (9/12) or an appearance consistent with pattern dystrophy (3/12). In both phenotypes pale deposits and pigment clumping were seen at the level of the retinal pigment epithelium, with occasional changes also noted outside the arcades and nasal to the optic nerve. Fundus AF imaging revealed decreased autofluorescence in areas of atrophy and increased AF of the pale subretinal deposits. In areas of the retina that appeared normal clinically, variable sized flecks of increased and decreased AF were present. CONCLUSIONS The mitochondrial DNA A3243G point mutation can result in disease with a variable presentation. Fundus autofluorescence reveals a recognisable phenotype in most cases that is different from other macular dystrophies.
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Affiliation(s)
- P P Rath
- Moorfields Eye Hospital, London, UK
- Retina Vitreous Consultants, Pittsburgh, PA, USA
| | - S Jenkins
- Moorfields Eye Hospital, London, UK
- Institute of Ophthalmology, London, UK
| | - M Michaelides
- Moorfields Eye Hospital, London, UK
- Institute of Ophthalmology, London, UK
| | - A Smith
- Moorfields Eye Hospital, London, UK
- County Hospital, Hereford, UK
| | - M G Sweeney
- Department of Molecular Neuroscience, Institute of Neurology, London, UK
| | - M B Davis
- Department of Molecular Neuroscience, Institute of Neurology, London, UK
| | | | - A C Bird
- Moorfields Eye Hospital, London, UK
- Institute of Ophthalmology, London, UK
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106
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Murphy R, Turnbull DM, Walker M, Hattersley AT. Clinical features, diagnosis and management of maternally inherited diabetes and deafness (MIDD) associated with the 3243A>G mitochondrial point mutation. Diabet Med 2008; 25:383-99. [PMID: 18294221 DOI: 10.1111/j.1464-5491.2008.02359.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maternally inherited diabetes and deafness (MIDD) affects up to 1% of patients with diabetes but is often unrecognized by physicians. It is important to make an accurate genetic diagnosis, as there are implications for clinical investigation, diagnosis, management and genetic counselling. This review summarizes the range of clinical phenotypes associated with MIDD; outlines the advances in genetic diagnosis and pathogenesis of MIDD; summarizes the published prevalence data and provides guidance on the clinical management of these patients and their families.
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Affiliation(s)
- R Murphy
- Institute of Biomedical Sciences, Peninsula Medical School, Exeter, UK.
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107
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Takeuchi J, Tashiro J, Nakagaki O, Yoshida M, Kamoshima H, Oku K, Yoshioka N. [A case of maternally inherited diabetes with deafness (MIDD) occurring at an advanced age]. Nihon Ronen Igakkai Zasshi 2008; 45:95-9. [PMID: 18332579 DOI: 10.3143/geriatrics.45.95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We report an elderly patient with maternally inherited diabetes with deafness (MIDD). A 69-year-old woman was found to be diabetic for the first time when she visited her local medical doctor for the symptoms of a common cold. Her casual plasma glucose level was 311 mg/dl and HbA1c was 8.3%. She had been aware of muscle atrophy of the lower extremities and hearing disturbance since age 66. As for her family history, her mother, older sister and younger brother were diabetic with hearing difficulty and all of them had died suddenly in their middle age. Her 45-year-old daughter was also diabetic with some difficulty in hearing. Therefore, we suspected both the patient and her daughter had MIDD, and found alterations in mitochondrial DNA3243A-G. MIDD is a condition that needs to be diagnosed accurately and treated at an early stage, since diabetic complications can progress rapidly and could cause myocardial complications and mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). According to a report of 115 cases of MIDD in Japan, MIDD had been diagnosed at the age of 32.8 on average and our case was strikingly old for the age of onset of the disease.
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Affiliation(s)
- Jun Takeuchi
- Department of Medicine II, Hokkaido University Graduate School of Medicine
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108
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Schaefer AM, McFarland R, Blakely EL, He L, Whittaker RG, Taylor RW, Chinnery PF, Turnbull DM. Prevalence of mitochondrial DNA disease in adults. Ann Neurol 2008; 63:35-9. [PMID: 17886296 DOI: 10.1002/ana.21217] [Citation(s) in RCA: 392] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Diverse and variable clinical features, a loose genotype-phenotype relationship, and presentation to different medical specialties have all hindered attempts to gauge the epidemiological impact of mitochondrial DNA (mtDNA) disease. Nevertheless, a clear understanding of its prevalence remains an important goal, particularly about planning appropriate clinical services. Consequently, the aim of this study was to accurately define the prevalence of mtDNA disease (primary mutation occurs in mtDNA) in the working-age population of the North East of England. METHODS Adults with suspected mitochondrial disease in the North East of England were referred to a single neurology center for investigation from 1990 to 2004. Those with pathogenic mtDNA mutations were identified and pedigree analysis performed. For the midyear period of 2001, we calculated the minimum point prevalence of mtDNA disease for adults of working age (>16 and <60/65 years for female/male patients, respectively). RESULTS In this population, we found that 9.2 in 100,000 people have clinically manifest mtDNA disease, making this one of the commonest inherited neuromuscular disorders. In addition, a further 16.5 in 100,000 children and adults younger than retirement age are at risk for development of mtDNA disease. INTERPRETATION Through detailed pedigree analysis and active family tracing, we have been able to provide revised minimum prevalence figures for mtDNA disease. These estimates confirm that mtDNA disease is a common cause of chronic morbidity and is more prevalent than has been previously appreciated.
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Affiliation(s)
- Andrew M Schaefer
- Mitochondrial Research Group, School of Neurology, Neurobiology and Psychiatry, Newcastle University, Newcastle upon Tyne, United Kingdom
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109
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Abstract
Type 2 diabetes (T2D) and obesity are recognized as conditions of growing biomedical importance to societies worldwide. Despite this, lack of understanding concerning the processes which normally serve to maintain weight and to regulate glucose concentrations, and ignorance about the mechanisms by which these homeostatic processes fail, remains a significant obstacle to the development of improved tools for management and prevention. There has been a long-standing belief that the identification of the specific genes influencing development of these conditions has the potential to reveal these fundamental processes, thereby providing vital clues to support clinical advances. Furthermore, there has been the hope that this information will translate into the capacity to deliver more 'personalized' medical care, whereby management can be tailored in accordance with an appreciation of individual molecular pathogenesis. As this review indicates, these developments are already a reality for selected monogenic forms of diabetes and obesity. Recent advances in the identification of genes underlying multifactorial forms of these conditions will accelerate efforts to effect similar clinical translation across the full spectrum of disease.
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110
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Uusimaa J, Moilanen JS, Vainionpää L, Tapanainen P, Lindholm P, Nuutinen M, Löppönen T, Mäki-Torkko E, Rantala H, Majamaa K. Prevalence, segregation, and phenotype of the mitochondrial DNA 3243A>G mutation in children. Ann Neurol 2007; 62:278-87. [PMID: 17823937 DOI: 10.1002/ana.21196] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE We studied the prevalence, segregation, and phenotype of the mitochondrial DNA 3243A>G mutation in children in a defined population in Northern Ostrobothnia, Finland. METHODS Children with diagnoses commonly associated with mitochondrial diseases were ascertained. Blood DNA from 522 selected children was analyzed for 3243A>G. Children with the mutation were clinically examined. Information on health history before the age of 18 years was collected from previously identified adult patients with 3243A>G. Mutation segregation analysis in buccal epithelial cells was performed in mothers with 3243A>G and their children whose samples were analyzed anonymously. RESULTS Eighteen children were found to harbor 3243A>G in a population of 97,609. A minimum estimate for the prevalence of 3243A>G was 18.4 in 100,000 (95% confidence interval, 10.9-29.1/100,000). Information on health in childhood was obtained from 37 adult patients with 3243A>G. The first clinical manifestations appearing in childhood were sensorineural hearing impairment, short stature or delayed maturation, migraine, learning difficulties, and exercise intolerance. Mutation analysis from 13 mothers with 3243A>G and their 41 children gave a segregation rate of 0.80. The mothers with heteroplasmy greater than 50% tended to have offspring with lower or equal heteroplasmy, whereas the opposite was true for mothers with heteroplasmy less than or equal to 50% (p = 0.0016). INTERPRETATION The prevalence of 3243A>G is relatively high in the pediatric population, but the morbidity in children is relatively low. The random genetic drift model may be inappropriate for the transmission of the 3243A>G mutation.
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Affiliation(s)
- Johanna Uusimaa
- Department of Paediatrics, University of Oulu, Oulu, Finland
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111
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Bensch KG, Degraaf W, Hansen PA, Zassenhaus HP, Corbett JA. A transgenic model to study the pathogenesis of somatic mtDNA mutation accumulation in beta-cells. Diabetes Obes Metab 2007; 9 Suppl 2:74-80. [PMID: 17919181 DOI: 10.1111/j.1463-1326.2007.00776.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Low levels of somatic mutations accumulate in mitochondrial DNA (mtDNA) as we age; however, the pathogenic nature of these mutations is unknown. In contrast, mutational loads of >30% of mtDNA are associated with electron transport chain defects that result in mitochondrial diseases such as mitochondrial encephalopathy lactic acidosis and stroke-like episodes. Pancreatic beta-cells may be extremely sensitive to the accumulation of mtDNA mutations, as insulin secretion requires the mitochondrial oxidation of glucose to CO(2). Type 2 diabetes arises when beta-cells fail to compensate for the increased demand for insulin, and many type 2 diabetics progress to insulin dependence because of a loss of beta-cell function or beta-cell death. This loss of beta-cell function/beta-cell death has been attributed to the toxic effects of elevated levels of lipids and glucose resulting in the enhanced production of free radicals in beta-cells. mtDNA, localized in close proximity to one of the major cellular sites of free radical production, comprises more than 95% coding sequences such that mutations result in changes in the coding sequence. It has long been known that mtDNA mutations accumulate with age; however, only recently have studies examined the influence of somatic mtDNA mutation accumulation on disease pathogenesis. This article will focus on the effects of low-level somatic mtDNA mutation accumulation on ageing, cardiovascular disease and diabetes.
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Affiliation(s)
- K G Bensch
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St Louis, MO, USA
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112
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Li JY, Hsieh RH, Peng NJ, Lai PH, Lee CF, Lo YK, Wei YH. A follow-up study in a Taiwanese family with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes syndrome. J Formos Med Assoc 2007; 106:528-36. [PMID: 17660142 DOI: 10.1016/s0929-6646(07)60003-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND/PURPOSE MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) syndrome is often associated with A3243G point mutation of mitochondrial DNA (mtDNA). We previously described a MELAS family characterized by harboring an additional approximately 260 bp tandem duplication in the D-loop and a novel C3093G point mutation in the 16S rRNA gene of mtDNA in the proband. We studied the clinical progression and fluctuation of mtDNA mutations in this Taiwanese MELAS family. METHODS We followed up the clinical course in all members of this family (1 proband, her mother and 3 sons) for 12 years. Mutations of mtDNA in serial muscle biopsies of the proband and blood samples and hair follicles taken at different time points from the members of this family were analyzed. RESULTS The proband developed repeated stroke-like episodes, chronic intestinal pseudo-obstruction, polyneuropathy, progressive renal failure and dilated cardiomyopathy with heart failure. During the follow-up period, the mother and one of the siblings of the proband developed stroke-like episodes at age 62 and 12, respectively. There was no significant difference in the proportions of mtDNA with A3243G mutation among five serial muscle biopsies of the proband. In one carrier (I-2), the proportion of A3243G mutated mtDNA in blood cells was slightly increased with disease progression. CONCLUSION This study underlines the importance of early detection of extraneuromuscular symptoms in the members of a family with MELAS syndrome by adequate follow-up. The age of onset of stroke-like episode in MELAS syndrome may be as late as 62 years. We suggest that the manifestations of MELAS syndrome in this family might be associated with the additional approximately 260 bp tandem duplication in the D-loop region and the coexistence of C3093G mutation in the 16S rRNA gene with the A3243G mutation of mtDNA.
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Affiliation(s)
- Jie-Yuan Li
- Division of Neurology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
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113
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Ichinose K, Kawasaki E, Eguchi K. Recent advancement of understanding pathogenesis of type 1 diabetes and potential relevance to diabetic nephropathy. Am J Nephrol 2007; 27:554-64. [PMID: 17823503 DOI: 10.1159/000107758] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 07/16/2007] [Indexed: 01/22/2023]
Abstract
Type 1 diabetes mellitus is an autoimmune disease characterized by progressive destruction of pancreatic beta cells by genetic and environmental factors which leads to an absolute dependence of insulin for survival and maintenance of health. Although the majority of mechanisms of beta cell destruction remain unclear, many molecules, including proinflammatory cytokines and chemokines such as tumor necrosis factor alpha and monocyte chemoattractant protein-1, are implicated in the development of beta cell damage. Furthermore, beta cell destruction is enhanced by the Th1 and Th17 subsets of CD4+ T cells. In contrast, there are mechanisms involved in the maintenance of peripheral tolerance by regulatory T cells, the function of which depends on the pleiotropic cytokine transforming growth factor beta. Development and progression of renal injuries in patients with diabetic nephropathy are also associated with several growth factors and proinflammatory cytokines, including tumor necrosis factor alpha, insulin-like growth factor-1, monocyte chemoattractant protein-1, vascular endothelial growth factor, and transforming growth factor beta. Although the pathogenic mechanisms underlying type 1 diabetes and diabetic nephropathy are principally different, i.e., autoimmunity and inflammation, some common factors, including susceptibility genes and proinflammatory cytokines, are involved in both mechanisms, including infiltrating cell recruitment, upregulation of other cytokines and chemokines, or apoptosis.
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Affiliation(s)
- Kunihiro Ichinose
- Unit of Translational Medicine, Department of Rheumatology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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114
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Park SY, Lee W. The depletion of cellular mitochondrial DNA causes insulin resistance through the alteration of insulin receptor substrate-1 in rat myocytes. Diabetes Res Clin Pract 2007; 77 Suppl 1:S165-71. [PMID: 17462778 DOI: 10.1016/j.diabres.2007.01.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/29/2007] [Indexed: 01/07/2023]
Abstract
Since the bioenergetic capacity of skeletal muscle mitochondria is decreased in type 2 diabetes and obesity, the reduction of mitochondrial DNA (mtDNA) content may be involved in the development of insulin resistance in skeletal muscle. To elucidate the association of cellular mtDNA content and insulin resistance, we produced L6 GLUT4myc myocytes depleted of mtDNA by long-term treatment with ethidium bromide (EtBr). L6 GLUT4myc cells cultured with 0.2 microg/ml EtBr (termed depleted cells) revealed a marked decrease in cellular mtDNA, concomitant with a lack of mRNAs encoded by mtDNA. Interestingly, the mtDNA-depleted cells showed a drastic decrease in basal and insulin-stimulated glucose uptake, indicating that L6 GLUT4myc cells develop impaired glucose utilization and insulin resistance. The repletion of mtDNA normalized basal and insulin-stimulated glucose uptake. The plasma membrane (PM) GLUT4 in the basal state was decreased, and the insulin-stimulated GLUT4 translocation to the PM was drastically reduced by mtDNA depletion. Interestingly, the expression of IRS-1 associated with insulin signaling was decreased by 90% in the depleted cells, and the insulin-stimulated phosphorylation of IRS-1 and Akt2/PKB were drastically reduced in the depleted cells. Those changes returned to control levels after mtDNA repletion. Taken together, our data suggest that PM GLUT4 content and insulin signal pathway intermediates are modulated by the alteration of cellular mtDNA content, and the reduction in the expression of IRS-1 and insulin-stimulated phosphorylation of IRS-1 and Akt2/PKB are associated with insulin resistance in the mtDNA-depleted L6 GLUT4myc myocytes.
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Affiliation(s)
- Seung Y Park
- Department of Biochemistry, College of Medicine, Dongguk University, Kyungju 780-714, Korea
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115
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Greer DM, Cagliero E, Krakauer EL, Gonzalez RG, Hedley-Whyte ET. Case records of the Massachusetts General Hospital. Case 21-2007. A 58-year-old woman with headaches, weakness, and strokelike episodes. N Engl J Med 2007; 357:164-73. [PMID: 17625129 DOI: 10.1056/nejmcpc079015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- David M Greer
- Department of Neurology, Harvard Medical School, USA
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116
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Abstract
Hearing loss is an etiologically diverse condition with many disease-related complications and major clinical, social, and quality of life implications. As the rate of acquired hearing loss secondary to environmental causes decreases and improvements in the diagnosis of abnormalities occur, the significance of genetic factors that lead to deafness increases. Advancements in molecular biology have led to improved detection and earlier intervention in patients with hearing loss. Subsequently, earlier implementation of educational services and cochlear implant technology in patients with profound hearing loss now results in superior communication skills and enhanced language development. The aim of this review is to provide a comprehensive framework underlying the causes of hearing impairment and to detail the clinical management for patients with hereditary hearing loss.
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Affiliation(s)
- Amit Kochhar
- Molecular Otolaryngology Research Laboratories, University of Iowa, Iowa City, Iowa 52242, USA
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117
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Sahu RP, Aggarwal A, Zaidi G, Shah A, Modi K, Kongara S, Aggarwal S, Talwar S, Chu S, Bhatia V, Bhatia E. Etiology of early-onset type 2 diabetes in Indians: islet autoimmunity and mutations in hepatocyte nuclear factor 1alpha and mitochondrial gene. J Clin Endocrinol Metab 2007; 92:2462-7. [PMID: 17440016 DOI: 10.1210/jc.2006-2467] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Indians are at high risk of developing type 2 diabetes mellitus (T2DM) at an early age, despite their lower body mass index. Studies on the etiology of patients presenting as early-onset T2DM in this racial group are not available. OBJECTIVE The objective was to delineate the clinical features in young Indian patients with T2DM and to determine the role of mutations in the hepatocyte nuclear factor 1alpha (HNF1alpha) gene [MODY3 (maturity-onset diabetes of the young, type 3)], mitochondrial A3243G mutation, and islet autoimmunity in its etiology. DESIGN This was an observational cohort study. SETTING The setting was an outpatient diabetes clinic in a teaching hospital. PATIENTS Ninety-six consecutive young patients with T2DM (onset, <or=30 yr) were included in the study. INTERVENTIONS Glutamic acid decarboxylase and insulinoma antigen 2 antibodies, mitochondrial A3243G mutation, and the common HNF1alpha mutation P291fsinsC were measured in all patients. The entire HNF1alpha gene was studied for mutations in 32 subjects with onset less than 25 yr or with normal weight. The common HNF1alpha A98V polymorphism was studied in 91 patients. RESULTS The patients were clinically heterogeneous, with 42% having a normal body mass index. Glutamic acid decarboxylase antibodies were present in three (3%) subjects and mitochondrial A3243G mutation in one (1%) subject. The P291fsinsC mutation was not detected in any patient. A MODY3 mutation (R200W) was detected in one patient (3%). In this family, diabetes cosegregated with the R200W mutation in the proband and his youngest brother but not in three paternal uncles. The Val 98 allele was associated with T2DM (allele frequency, 0.14 vs. 0.03 in controls; odds ratio, 5.2; P < 0.001). CONCLUSIONS Despite a significant proportion of young Indian patients with T2DM having normal weight, islet autoimmunity, A3243G mitochondrial, and HNF1alpha gene mutations were infrequent.
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Affiliation(s)
- Ravi P Sahu
- Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, India
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118
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Watanabe RM, Black MH, Xiang AH, Allayee H, Lawrence JM, Buchanan TA. Genetics of gestational diabetes mellitus and type 2 diabetes. Diabetes Care 2007; 30 Suppl 2:S134-40. [PMID: 17596461 PMCID: PMC2925642 DOI: 10.2337/dc07-s205] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Richard M Watanabe
- Department of Preventive Medicine, Keck School of Medicine of USC, Los Angeles, CA 90089-9011, USA.
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Salles JEN, Kalinin LB, Ferreira SRG, Kasamatsu T, Moisés RS. Diabetes mellitus associado à mutação mitocondrial A3243G: freqüência e caracterização clínica. ACTA ACUST UNITED AC 2007; 51:559-65. [PMID: 17684616 DOI: 10.1590/s0004-27302007000400009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 12/13/2006] [Indexed: 11/22/2022]
Abstract
Diabetes mitocondrial é freqüentemente associado à mutação mitocondrial A3243G. A prevalência desse subtipo de diabetes na população diabética varia de 0,5 a 3%, dependendo do grupo populacional estudado. OBJETIVO: Examinar a freqüência e o quadro clínico do diabetes associado com a mutação mitocondrial A3243G em pacientes brasileiros com tolerância a glicose alterada. MÉTODOS: A população estudada foi composta por 78 indivíduos portadores de diabetes mellitus tipo 1 (grupo I), 148 diabéticos tipo 2 (grupo II), 15 diabéticos tipo 1 ou tipo 2 portadores de disacusia (grupo III) e 492 indivíduos da comunidade nipo-brasileira com vários graus de intolerância a glicose. O DNA foi extraído de leucócitos do sangue periférico e a mutação A3243G foi determinada através da amplificação por PCR e digestão por Apa 1. Em alguns pacientes, o DNA também foi extraído da mucosa oral e folículo capilar. A mutação A3243G foi identificada em três indivíduos, todos do grupo III, resultando em uma prevalência de 0,4%. Os carreadores da mutação apresentavam diagnóstico do diabetes em idade jovem, índice de massa corpórea normal ou baixo e requerimento de insulina. CONCLUSÃO: Diabetes mitocondrial é um subtipo raro de diabetes em nossa população e deve ser investigado naqueles indivíduos portadores de diabetes e surdez.
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Affiliation(s)
- João Eduardo N Salles
- Departamento de Medicina, Universidade Federal de São Paulo, Rua Botucatu 740, 04034-970 São Paulo, SP
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120
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Abstract
Non-syndromic deafness can be caused by mutations in both nuclear and mitochondrial genes. More than 50 nuclear genes have been shown to be involved in non-syndromic hearing loss, but mutations in mitochondrial DNA (mtDNA) might also cause hearing impairment. As mitochondria are responsible for oxidative phosphorylation, the primary energy-producing system in all eukaryotic cells, mitochondrial dysfunction has pleiotropic effects. Many mutations in mtDNA can lead to multisystem disorders, such as Kearns-Sayre syndrome, NARP, MELAS, or MERRF syndromes, the presentation of which may include hearing loss. A more specific association of mitochondrially inherited deafness and diabetes known as MIDD syndrome can be caused by a limited number of specific mitochondrial mutations. In addition, several rare mutations in the mitochondrial MTTS1 and MTRNR1 genes have been found to be responsible for non-syndromic hearing loss. The most frequent form of non-syndromic deafness is presbyacusis, affecting more than 50% of the elderly. This age-related hearing loss is a paradigm for multifactorial inheritance, involving a multitude of inherited and acquired mutations in the nuclear and mitochondrial genomes, each with a low penetrance, in complex interplay with environmental factors, such as ototoxic medication, that accumulate with age. This study reviews the different mitochondrial mutations, leading to syndromic and especially non-syndromic deafness.
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Affiliation(s)
- H Kokotas
- Department of Genetics, Institute of Child Health, Athens, Greece
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121
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Manwaring N, Jones MM, Wang JJ, Rochtchina E, Howard C, Mitchell P, Sue CM. Population prevalence of the MELAS A3243G mutation. Mitochondrion 2007; 7:230-3. [PMID: 17300999 DOI: 10.1016/j.mito.2006.12.004] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2006] [Revised: 12/05/2006] [Accepted: 12/27/2006] [Indexed: 10/23/2022]
Abstract
We aimed to establish the population prevalence of the MELAS 3243A>G mtDNA mutation in a large Caucasian-based population (n=2954; 99% Caucasian, 57% women and mean age of 66.4 years). All participants underwent comprehensive clinical evaluation including audiologic testing. We detected the 3243A>G mutation in seven subjects using standard polymerase chain reaction/restriction fragment length polymorphism methods, establishing a population prevalence of 236/100000 (0.24%; 95% CI 0.10-0.49%); much higher than previously reported. All had mild to moderate hearing loss. Our findings indicate that subjects with the 3243A>G mtDNA mutation could be markedly under-recognised in the community.
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Affiliation(s)
- Neil Manwaring
- Kolling Institute, Department of Neurogenetics, University of Sydney, Clinic 4, Royal North Shore Hospital, Reserve Road, St. Leonards, NSW 2065, Australia
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122
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Affiliation(s)
- Deborah P Wubben
- Department of Medicine, Endocrinology, University of Wisconsin Medical School, Madison, Wisconsin 53792-5148, USA
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123
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Sáfrány E, Csöngei V, Járomi L, Maász A, Magyari L, Sipeky C, Melegh B. Mitochondrial DNA and its mutations: novel fields in a new era. Orv Hetil 2007; 148:971-8. [PMID: 17513250 DOI: 10.1556/oh.2007.28014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Az utóbbi két évtizedet tartják a klinikai mitokondriális DNS-kutatás aranykorának. Folyamatosan bővül a patológiás variánsok száma, amelyek betegséggel társulnak, illetve bővül az ismeretanyag azokról az entitásokról, melyek hátterében a mitokondriális DNS kóros elváltozásai állnak. A cirkuláris mitokondriális DNS öröklődése eltér a Mendel-féle szabályoktól, anyai öröklésmenetet mutat; számos vonatkozásban eltérő sajátosságokkal rendelkezik a nukleáris DNS-hez viszonyítva. A molekuláris biológiai módszerek terjedésével egyre több kórkép ismerhető fel, noha a diagnosztika manapság is komoly kihívást jelent. Napjainkban a mitokondriális medicina számos orvosi szubspecialitáshoz kapcsolódóan jelentős előrelépéseket mutatott; így körvonalazódott a mitokondriális gasztroenterológia, endokrinológia, otológia, oftalmológia, nefrológia, hematológia, onkológia, reproduktív medicina és pszichiátria, mintegy az adott szubspecialitás mitokondriális DNS-sel kapcsolatos, többé-kevésbé részleges önállósodással megjelenő territóriuma. A jelen összefoglaló közlemény a mitokondriális medicina rövid, általános összefoglalása mellett e fejezetekre próbál rátekintést nyújtani.
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Affiliation(s)
- Eniko Sáfrány
- Pécsi Tudományegyetem, Altalános Orvostudományi Kar Orvosi Genetikai és Gyermekfejlodéstani Intézet, Pécs, Szigeti u. 12. 7624
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124
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Araki E, Miyazaki JI. Metabolic disorders in diabetes mellitus: impact of mitochondrial function and oxidative stress on diabetes and its complications. Antioxid Redox Signal 2007; 9:289-91. [PMID: 17184179 DOI: 10.1089/ars.2006.1486] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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125
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Nishikawa T, Araki E. Impact of mitochondrial ROS production in the pathogenesis of diabetes mellitus and its complications. Antioxid Redox Signal 2007; 9:343-53. [PMID: 17184177 DOI: 10.1089/ars.2006.1458] [Citation(s) in RCA: 298] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this review, the impacts of mitochondrial reactive oxygen species (ROS) on diabetes and its complications are described. In endothelial cells, high-glucose treatment increases mitochondrial ROS and normalization of the ROS production by inhibitors of mitochondrial metabolism, or by overexpression of UCP-1 or MnSOD, prevents glucose-induced activation of PKC, formation of AGE, and accumulation of sorbitol, all of which are believed to be the main molecular mechanisms of diabetic complications. Glomerular hyperfiltration, one of the characteristics of early diabetic nephropathy, may be caused by mitochondrial ROS through activation of COX-2 gene transcription, followed by PGE2 overproduction. In pancreatic beta cells, hyperglycemia also increases mitochondrial ROS, which suppresses the first phase of glucose-induced insulin secretion, at least in part, through the suppression of GAPDH activity. In liver cells, similar to that in hyperglycemia, TNF-alpha increases mitochondrial ROS, which in turn activates apoptosis signal-regulating kinase 1 (ASK1) and c-jun NH2-terminal kinases (JNK), increases serine phosphorylation of IRS-1, and decreases insulin-stimulated tyrosine phosphorylation of IRS-1, leading to insulin resistance. These results suggest the importance of mitochondrial ROS in the pathogenesis of diabetes mellitus and its complications through modification of various cellular events in many tissues, including vessels, kidney, pancreatic beta cells, and liver.
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Affiliation(s)
- Takeshi Nishikawa
- Department of Metabolic Medicine, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
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126
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Malecki MT, Skupien J, Klupa T, Naskalska A, Gorczynska-Kosiorz S, Moczulski DK, Sieradzki J. Maternally inherited diabetes with deafness and obesity: body weight reduction response to treatment with insulin analogues. Rev Diabet Stud 2007; 3:205-7. [PMID: 17487345 PMCID: PMC1828285 DOI: 10.1900/rds.2006.3.205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Maternally inherited diabetes with deafness (MIDD) is a rare, monogenic form of diabetes mellitus caused by mutations in the mitochondrial genome, the most frequent being the A3243G substitution of the tRNA(Leu) gene. We screened 520 individuals with type 2 diabetes mellitus and 45 probands from families with a clinical picture of maturity onset diabetes of the young (MODY) using restriction fragment length polymorphism. One carrier of the mutation being investigated was found in a proband from a MODY family. The patient was a 20 year-old woman, diagnosed at the age of 16 years as having type 1 diabetes mellitus. On entry to the study, she was treated by a multiple daily injection regimen (MDI) with regular human insulin and human NPH insulin. Typical extra-pancreatic symptoms of MIDD were present, such as macular pattern dystrophy and mild bilateral sensory hearing loss. Additionally, the patient presented abdominal obesity (BMI 32.0), an uncommon feature in monogenic insulin secretion defects, including MIDD. To facilitate weight loss, the diabetes treatment was modified. Since metformin treatment is considered to be contraindicated in MIDD because of the increased risk of lactic acidosis, we used insulin analogues (aspart and detemir) in an MDI regimen and hypocaloric diet. This resulted in a 6.3 kg weight reduction (BMI 27.4) and normalization of HbA1c level (from 7.2 to 6.1 %) during a three-month follow-up. On the basis of this case, we suggest that an MDI regimen with insulin analogues may be a preferred therapeutic option in some rare clinical situations, such as MIDD associated with obesity.
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Affiliation(s)
- Maciej T. Malecki
- Department of Metabolic Diseases, Jagiellonian University, Medical College, Krakow, Poland
- Address correspondence to: Maciej T. Malecki, e-mail:
| | - Jan Skupien
- Department of Metabolic Diseases, Jagiellonian University, Medical College, Krakow, Poland
| | - Tomasz Klupa
- Department of Metabolic Diseases, Jagiellonian University, Medical College, Krakow, Poland
| | - Antonina Naskalska
- Department of Metabolic Diseases, Jagiellonian University, Medical College, Krakow, Poland
| | - Sylwia Gorczynska-Kosiorz
- Department of Internal Medicine, Diabetology and Nephrology, Silesian School of Medicine, Zabrze, Poland
| | - Dariusz K. Moczulski
- Department of Internal Medicine, Diabetology and Nephrology, Silesian School of Medicine, Zabrze, Poland
| | - Jacek Sieradzki
- Department of Metabolic Diseases, Jagiellonian University, Medical College, Krakow, Poland
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127
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Kato T, Kubota M, Kasahara T. Animal models of bipolar disorder. Neurosci Biobehav Rev 2007; 31:832-42. [PMID: 17466374 DOI: 10.1016/j.neubiorev.2007.03.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 03/06/2007] [Accepted: 03/13/2007] [Indexed: 12/31/2022]
Abstract
Animal models of human diseases should meet three sets of criteria: construct validity, face validity, and predictive validity. To date, several putative animal models of bipolar disorder have been reported. They are classified into various categories: pharmacological models, nutritional models, environmental models, and genetic models. None of them, however, totally fulfills the three validity criteria, and thus may not be useful for drug development. Mounting evidence suggests that mitochondrial dysfunction has a role in bipolar disorder. To test whether accumulation of mtDNA deletions in the brain can cause bipolar disorder, we generated transgenic mice with neuron-specific expression of mutant Polg (D181A). These mice showed altered diurnal activity rhythm and periodic activity change associated with the estrous cycle. These phenotypes were worsened by administration of a tricyclic antidepressant, but improved after lithium treatment. This mouse model of bipolar disorder potentially fulfills the three validity criteria, and therefore might be used for future drug development studies.
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Affiliation(s)
- Tadafumi Kato
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
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128
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Salles JE, Kasamatsu TS, Dib SA, Moisés RS. Beta-cell function in individuals carrying the mitochondrial tRNA leu (UUR) mutation. Pancreas 2007; 34:133-7. [PMID: 17198195 DOI: 10.1097/01.mpa.0000246659.38375.4d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES To assess the beta-cell function in individuals with mitochondrial DNA A3243G mutation with normal glucose tolerance (NGT) or diabetes mellitus (DM). Furthermore, in diabetic individuals, we evaluated the effect of coenzyme Q10 supplementation on insulin secretory response. METHODS Eight mutation-positive individuals with NGT (n = 4) or DM (n = 4) were studied. beta-Cell function was evaluated by C-peptide levels before and after a mixed liquid meal (Sustacal) challenge and by first-phase insulin response. RESULTS Fasting and Sustacal-stimulated C-peptide levels were significantly lower in diabetic patients than that in controls (area under the curve: 104.1 +/- 75.7 vs 520.8 +/- 173.8, P = 0.001), whereas in individuals with NGT, this response was preserved (area under the curve: 537.8 +/- 74.3 vs 520.8 +/- 179.8, P = 0.87). The duration of diabetes was negatively correlated with fasting C-peptide levels (r = -0.961, P = 0.038). Among the 3 patients with residual insulin secretion, the short-term treatment with coenzyme Q10 (3 months) improved C-peptide levels in 2 of them. The first-phase insulin response was diminished in 2 individuals with NGT, the oldest ones. CONCLUSIONS We showed an impaired insulin secretory capacity in individuals carrying the A3243G mutation, this possibly being the primary defect contributing to the development of DM. In addition, our data suggest that this could be a functional defect.
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Affiliation(s)
- João Eduardo Salles
- Division of Endocrinology, Department of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil
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129
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Kang D, Hamasaki N. Mitochondrial disease: maintenance of mitochondrial genome and molecular diagnostics. Adv Clin Chem 2006; 42:217-54. [PMID: 17131628 DOI: 10.1016/s0065-2423(06)42006-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mitochondrial DNA (mtDNA) is essential for the aerobic ATP synthesis system that is responsible for about 80% of normal cellular energy demands. In addition to rare genetic disorders causing neuromyopathy, alterations of mtDNA have been found also in so-called common diseases such as heart failure, diabetes, and cancer. Although some of these alterations are inherited, some are considered to be generated and/or accumulated in somatic cells with age. One reason for the somatic mutations is that mtDNA is more vulnerable than is nuclear DNA. For example, mitochondrial respiratory chain produces a large amount of reactive oxygen species as inevitable byproducts of oxidative phosphorylation. However, the molecular mechanisms for maintenance of mitochondrial genome are much less elucidated than those for nuclear genome. In spite of its increasing importance, the molecular diagnosis of mitochondrial DNA-related diseases is well done only in very limited expert laboratories. In this chapter, we focus on maintenance of mtDNA in somatic cells, its clinical importance, and recent developments of molecular tests.
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Affiliation(s)
- Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan
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130
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Rutter GA, Tsuboi T, Ravier MA. Ca2+ microdomains and the control of insulin secretion. Cell Calcium 2006; 40:539-51. [PMID: 17030367 DOI: 10.1016/j.ceca.2006.08.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 08/23/2006] [Indexed: 11/19/2022]
Abstract
Nutrient-induced increases in intracellular free Ca(2+) concentrations are the key trigger for insulin release from pancreatic islet beta-cells. These Ca(2+) changes are tightly regulated temporally, occurring as Ca(2+) influx-dependent baseline oscillations. We explore here the concept that locally high [Ca(2+)] concentrations (i.e. Ca(2+) microdomains) may control exocytosis via the recruitment of key effector proteins to sites of exocytosis. Importantly, recent advances in the development of organelle- and membrane-targeted green fluorescent protein (GFP-) or aequorin-based Ca(2+) indicators, as well as in rapid imaging techniques, are providing new insights into the potential role of these Ca(2+) microdomains in beta-cells. We summarise here some of the evidence indicating that Ca(2+) microdomains beneath the plasma membrane and at the surface of large dense core vesicles may be important in the normal regulation of insulin secretion, and may conceivably contribute to "ATP-sensitive K(+)-channel independent" effects of glucose. We also discuss evidence that, in contrast to certain non-excitable cells, direct transfer of Ca(2+) from the ER to mitochondria via localised physical contacts between these organelles is relatively less important for efficient mitochondrial Ca(2+) uptake in beta-cells. Finally, we discuss evidence from single cell imaging that increases in cytosolic Ca(2+) are not required for the upstroke of oscillations in mitochondrial redox state, but may underlie the reoxidation process.
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Affiliation(s)
- Guy A Rutter
- Department of Cell Biology, Division of Medicine, Imperial College London, Sir Alexander Fleming Building, London, UK.
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131
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Abstract
Fulminant type 1 diabetes exhibits distinct clinical futures from "classic" autoimmune type 1 diabetes. Although the etiology of fulminant type 1 diabetes is not fully elucidated, class II HLA could contribute to the development of fulminant type 1 diabetes. In Japanese patients with "classic" type 1 diabetes, DRB1*0405-DQB1*0401 and DRB1*0901-DQB1*0303 are major susceptible HLA-DR-DQ haplotypes, whereas DRB1*1502-DQB1*0601 and DRB1*1501-DQB1*0602 are protective. In contrast, only DRB1*0405-DQB1*0401, but not DRB1*0901-DQB1*0303, is a susceptible haplotype in fulminant type 1 diabetes. In addition, neither DRB1*1502-DQB1*0601 nor DRB1*1501-DQB1*0602 are protective haplotypes in fulminant type 1 diabetes. In genotypic combination analysis, the homozygotes of DRB1*0405-DQB1*0401 are associated with both fulminant type 1 diabetes and "classic" type 1 diabetes, whereas the homozygotes of DRB1*0901-DQB1*0303 are associated with only "classic" type 1 diabetes. These findings suggest a different contribution of class II HLA in the mechanisms of beta cell damage between fulminant and "classic" type 1 diabetes. To further address the pathogenesis of fulminant type 1 diabetes, HNF-1alpha gene mutation and mutation of the mitochondrial DNA were analyzed in patients with fulminant type 1 diabetes admitted to our department during the period from 1990 to 2000. Neither mutations of HNF-1alpha gene nor A-to-G mutation at nucleotide position 3,243 of the mitochondrial tRNA(LEU(UUR)) gene were identified in these patients. These results suggest that the HNF-1alpha gene mutation and mutation of the mitochondrial DNA are not likely associated with diabetic patients with fulminant clinical symptoms at disease onset. In this article we will summarize the current findings on the genetics of Japanese patients with fulminant type 1 diabetes.
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Affiliation(s)
- Eiji Kawasaki
- Department of Metabolism/Diabetes and Clinical Nutrition, Nagasaki University Hospital of Medicine and Dentistry, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan.
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132
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Scaglia F, Hsu CH, Kwon H, Bai RK, Perng CL, Chang HM, Dai P, Smith EO, Whiteman DAH, Feigenbaum A, Gropman A, Wong LJC. Molecular bases of hearing loss in multi-systemic mitochondrial cytopathy. Genet Med 2006; 8:641-52. [PMID: 17079881 DOI: 10.1097/01.gim.0000237781.10594.d1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Hearing loss is a common clinical feature in classic mitochondrial syndromes. The purpose of this study was to evaluate the diverse molecular etiologies and natural history of hearing loss in multi-systemic mitochondrial cytopathies and the possible correlation between degree of hearing loss and neurological phenotype. METHODS In this retrospective study we evaluated the clinical features and molecular bases of hearing loss associated with multi-systemic mitochondrial cytopathy. Forty-five patients with sensorineural hearing loss and definite diagnosis of mitochondrial cytopathy according to the published diagnostic criteria were studied. RESULTS The sensorineural hearing loss was progressive and for the most part symmetrical with involvement of the higher frequencies. Both cochlear and retrocochlear involvement were found in this cohort. No correlation was found between the degree of hearing loss and the number and severity of neurological manifestations. Deleterious mtDNA point mutations of undisputed pathogenicity were identified in 18 patients. The A3243G mutation was the most frequently encountered among this group. MtDNA depletion, over-replication, and multiple deletions were found in further 11 cases. CONCLUSION This study reveals an expanding spectrum of mtDNA abnormalities associated with hearing loss. No correlation was found between the degrees of hearing loss and the severity of neurological manifestations.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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133
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Scaglia F, Northrop JL. The mitochondrial myopathy encephalopathy, lactic acidosis with stroke-like episodes (MELAS) syndrome: a review of treatment options. CNS Drugs 2006; 20:443-64. [PMID: 16734497 DOI: 10.2165/00023210-200620060-00002] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mitochondrial encephalomyopathies are a multisystemic group of disorders that are characterised by a wide range of biochemical and genetic mitochondrial defects and variable modes of inheritance. Among this group of disorders, the mitochondrial myopathy, encephalopathy, lactic acidosis with stroke-like episodes (MELAS) syndrome is one of the most frequently occurring, maternally inherited mitochondrial disorders. As the name implies, stroke-like episodes are the defining feature of the MELAS syndrome, often occurring before the age of 15 years. The clinical course of this disorder is highly variable, ranging from asymptomatic, with normal early development, to progressive muscle weakness, lactic acidosis, cognitive dysfunction, seizures, stroke-like episodes, encephalopathy and premature death. This syndrome is associated with a number of point mutations in the mitochondrial DNA, with over 80% of the mutations occurring in the dihydrouridine loop of the mitochondrial transfer RNA(Leu(UUR)) [tRNA(Leu)((UUR))] gene. The pathophysiology of the disease is not completely understood; however, several different mechanisms are proposed to contribute to this disease. These include decreased aminoacylation of mitochondrial tRNA, resulting in decreased mitochondrial protein synthesis; changes in calcium homeostasis; and alterations in nitric oxide metabolism. Currently, no consensus criteria exist for treating the MELAS syndrome or mitochondrial dysfunction in other diseases. Many of the therapeutic strategies used have been adopted as the result of isolated case reports or limited clinical studies that have included a heterogeneous population of patients with the MELAS syndrome, other defects in oxidative phosphorylation or lactic acidosis due to disorders of pyruvate metabolism. Current approaches to the treatment of the MELAS syndrome are based on the use of antioxidants, respiratory chain substrates and cofactors in the form of vitamins; however, no consistent benefits have been observed with these treatments.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas 77030, USA.
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134
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Nohara S, Iwase M, Imoto H, Sasaki N, Nakamura U, Uchizono Y, Abe S, Doi Y, Iida M. Gastric emptying in patients with Type 2 diabetes mellitus and diabetes associated with mitochondrial DNA 3243 mutation using 13C-octanoic acid breath test. J Diabetes Complications 2006; 20:295-301. [PMID: 16949516 DOI: 10.1016/j.jdiacomp.2005.07.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 07/05/2005] [Accepted: 07/12/2005] [Indexed: 10/24/2022]
Abstract
Although the (13)C-octanoic acid breath test (OBT) has been applied to diabetic patients for assessing gastric emptying, such studies are still limited. Gastric emptying was measured using solid meal containing (13)C-octanoic acid in 52 patients with Type 2 diabetes mellitus and 4 diabetic patients with mitochondrial DNA (mitDNA) 3243 mutation. Delayed gastric emptying was detected in 29% of patients with Type 2 diabetes mellitus, and multiple regression analysis showed that gastric emptying was independently associated with gastrointestinal symptoms and cardiac autonomic neuropathy. Gastric emptying was not related to gastric dysrhythmia in cutaneous electrogastrography (EGG). Diabetic patients with mitDNA 3243 mutation showed delayed gastric emptying. Because the pathogenesis of delayed gastric emptying is multifactorial in diabetic patients, the recently developed OBT is useful for studying gastric emptying in various clinical settings of diabetic patients.
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Affiliation(s)
- Sakae Nohara
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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135
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de Andrade PBM, Rubi B, Frigerio F, van den Ouweland JMW, Maassen JA, Maechler P. Diabetes-associated mitochondrial DNA mutation A3243G impairs cellular metabolic pathways necessary for beta cell function. Diabetologia 2006; 49:1816-26. [PMID: 16736129 DOI: 10.1007/s00125-006-0301-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2005] [Accepted: 04/06/2006] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS Mitochondrial DNA (mtDNA) mutations cause several diseases, including mitochondrial inherited diabetes and deafness (MIDD), typically associated with the mtDNA A3243G point mutation on tRNALeu gene. The common hypothesis to explain the link between the genotype and the phenotype is that the mutation might impair mitochondrial metabolism expressly required for beta cell functions. However, this assumption has not yet been tested. METHODS We used clonal osteosarcoma cytosolic hybrid cells (namely cybrids) harbouring mitochondria derived from MIDD patients and containing either exclusively wild-type or mutated (A3243G) mtDNA. According to the importance of mitochondrial metabolism in beta cells, we studied the impact of the mutation on key parameters by comparing stimulation of these cybrids by the main insulin secretagogue glucose and the mitochondrial substrate pyruvate. RESULTS Compared with control mtDNA from the same patient, the A3243G mutation markedly modified metabolic pathways leading to a high glycolytic rate (2.8-fold increase), increased lactate production (2.5-fold), and reduced glucose oxidation (-83%). We also observed impaired NADH responses (-56%), negligible mitochondrial membrane potential, and reduced, only transient ATP generation. Moreover, cybrid cells carrying patient-derived mutant mtDNA exhibited deranged cell calcium handling with increased cytosolic loads (1.4-fold higher), and elevated reactive oxygen species (2.6-fold increase) under glucose deprivation. CONCLUSIONS/INTERPRETATION The present study demonstrates that the mtDNA A3243G mutation impairs crucial metabolic events required for proper cell functions, such as coupling of glucose recognition to insulin secretion.
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Affiliation(s)
- P B M de Andrade
- Department of Cell Physiology and Metabolism, University Medical Center, 1 rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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136
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Crispim D, Canani LH, Gross JL, Tschiedel B, Souto KEP, Roisenberg I. The European-specific mitochondrial cluster J/T could confer an increased risk of insulin-resistance and type 2 diabetes: an analysis of the m.4216T > C and m.4917A > G variants. Ann Hum Genet 2006; 70:488-95. [PMID: 16759180 DOI: 10.1111/j.1469-1809.2005.00249.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The aims of this study were to investigate the contributions of the mitochondrial DNA m.4216T > C and m.4917A > G variants, and also of the European-specific mitochondrial cluster J/T, to the development of type 2 diabetes mellitus in Caucasian-Brazilian patients from Southern Brazil. We analyzed 347 type 2 diabetes patients and 350 control subjects. Variant frequencies in patients and control subjects were compared using chi2 tests or odds ratio. We also compared clinical and laboratory characteristics among patients with and without the variants. We found that the frequencies of the m.4216T > C and m.4917A > G variants are higher in diabetic patients than in control subjects. Moreover, haplogroups J (partially defined by the presence of the m.4216T > C variant only) and T (partially defined by the presence of both m.4216T > C and m.4917A > G variants) are more frequent in the type 2 diabetic group than in the control group. Patients belonging to the cluster J/T are more insulin resistant than patients of other haplogroups. In conclusion, our results indicate the association of the cluster J/T (as suggested by analyses of the m.4216T > C and m.4917A > G variants) with insulin resistance and type 2 diabetes.
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Affiliation(s)
- D Crispim
- Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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137
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Lu J, Wang D, Li R, Li W, Ji J, Zhao J, Ye W, Yang L, Qian Y, Zhu Y, Guan MX. Maternally transmitted diabetes mellitus associated with the mitochondrial tRNA(Leu(UUR)) A3243G mutation in a four-generation Han Chinese family. Biochem Biophys Res Commun 2006; 348:115-9. [PMID: 16876129 DOI: 10.1016/j.bbrc.2006.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 07/03/2006] [Indexed: 11/21/2022]
Abstract
We report here the characterization of a four-generation Han Chinese family with maternally transmitted diabetes mellitus. Six (two males/four females) of eight matrilineal relatives in this family exhibited diabetes. The age of onset in diabetes varies from 15 years to 33 years, with an average of 26 years. Two of affected matrilineal relatives also exhibited hearing impairment. Molecular analysis of mitochondrial DNA (mtDNA) showed the presence of heteroplasmic tRNA(Lue(UUR)) A3243G mutation, ranging from 35% to 58% of mutations in blood cells of matrilineal relatives. The levels of heteroplasmic A3243G mutation seem to be correlated with the severity and age-at-onset of diabetes in this family. Sequence analysis of the complete mitochondrial genome in this pedigree revealed the presence of the A3243G mutation and 38 other variants belonging to the Eastern Asian haplogroup M7C. However, none of other mtDNA variants are evolutionarily conserved and implicated to have significantly functional consequence. Thus, the A3243G mutation is the sole pathogenic mtDNA mutation associated with diabetes in this Chinese family.
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Affiliation(s)
- Jianxin Lu
- Zhejiang Provincial Key Laboratory of Medical Genetics, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325003, China
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138
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Tang DL, Zhou X, Li X, Zhao L, Liu F. Variation of mitochondrial gene and the association with type 2 diabetes mellitus in a Chinese population. Diabetes Res Clin Pract 2006; 73:77-82. [PMID: 16414144 DOI: 10.1016/j.diabres.2005.12.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 12/01/2005] [Indexed: 11/24/2022]
Abstract
Mitochondrial DNA (mtDNA) variants have been implicated in many diseases including diabetes mellitus. To explore whether these genetic variants contribute to the susceptibility for type 2 diabetes mellitus (T2DM) in a Chinese population, a total of 184 T2DM cases and 279 matched healthy controls were recruited. PCR restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing were used to determine the variants of mtDNA (including T16189C, G3316A, T3394C, A14693G, A3243G and C1310T). Some of them were further analyzed by mfold or tRNA-scan-SE software. A homoplastic A14693G, for the first time, was found in 4 of 184 Chinese cases, the frequency of A14693G and T3394C was 2.17% and 2.72%, respectively, in patients but not in the controls. Secondary structure prediction revealed that there were obvious conformational changes in T3394C mutant ND1 versus wild type and A14693G mutant tRNA(Glu) protein versus wild type, providing additional clues to the disease pathogenesis although A3243G and C1310T mutations were not detected in any patients in the two groups. The 16189 variant among type 2 diabetes was more prevalent than in controls (36.9% versus 28.7%, P=0.039), and stepwise multiple regression analysis showed that the 16189 variant was an independent factor contributing to HOMA-IR (R(2)=0.043, P=0.037). Our results suggest that the mutations of T3394C and A14693G may contribute to genetic predisposition to T2DM, with the T16189C variant being associated with insulin resistance.
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Affiliation(s)
- Dong-Ling Tang
- Department of Clinical Laboratory, Zhongnan Hospital, Wuhan University, Donghu Road 169, Wuhan 430071, PR China
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139
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Salles JE, Moisés VA, Almeida DR, Chacra AR, Moisés RS. Myocardial dysfunction in mitochondrial diabetes treated with Coenzyme Q10. Diabetes Res Clin Pract 2006; 72:100-3. [PMID: 16253379 DOI: 10.1016/j.diabres.2005.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 08/21/2005] [Accepted: 09/01/2005] [Indexed: 11/17/2022]
Abstract
Maternally-inherited diabetes and deafness (MIDD) has been related to an A to G transition in the mitochondrial tRNA Leu (UUR) gene at the base pair 3243. Although some previous articles have reported that this mutation may be a cause of cardiomyopathy in diabetes, the degree of cardiac involvement and a specific treatment has not been established. Here, we reported a case of a patient with MIDD who developed congestive heart failure and the therapeutic usefulness of Coenzyme Q10 (CoQ10). In our patient, after the introduction of Coenzyme Q10 150 mg/day, there was a gradual improvement on left ventricular function evaluated by echocardiography. The fractional shortening (FS) and ejection fraction (EF) increased from 26 to 34% and from 49 to 64%, respectively. No side effects were noted. Three months after CoQ10 discontinuation, the parameters of systolic function evaluated by echocardiography decreased, suggesting that CoQ10 had a beneficial effect. Identification of diabetes and cardiomyopathy due to mitochondrial gene mutation may have therapeutic implications and Coenzyme Q10 is a possible adjunctive treatment in such patients.
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Affiliation(s)
- João Eduardo Salles
- Division of Endocrinology, Department of Medicine, Federal University of São Paulo, Rua Botucatu, 740 0434-970 São Paulo, SP, Brazil
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140
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Castro-Gago M, Blanco-Barca MO, Campos-González Y, Arenas-Barbero J, Pintos-Martínez E, Eirís-Puñal J. Epidemiology of pediatric mitochondrial respiratory chain disorders in northwest Spain. Pediatr Neurol 2006; 34:204-11. [PMID: 16504790 DOI: 10.1016/j.pediatrneurol.2005.07.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 06/21/2005] [Accepted: 07/27/2005] [Indexed: 11/16/2022]
Abstract
Our knowledge of mitochondrial respiratory chain diseases has increased dramatically in recent years, but relatively little information is available about their prevalence and incidence, either in pediatric or adult patients. This study reports incidence and prevalence estimates, and summarizes the clinical, biochemical, histologic, and genetic characteristics of 51 patients age 0-16 years. The overall annual incidence of all mitochondrial respiratory chain diseases was estimated to be 1.43 cases per 10(5) in the population as a whole, and 2.85 cases per 10(5) in the under-6 population. The overall prevalence of all mitochondrial respiratory chain diseases was estimated as 7.5 cases per 10(5) in the under-19 population, and 8.7 cases per 10(5) in the under-16 population. These incidence and prevalence estimates are higher than in most previous studies of pediatric populations. Estimated prevalences of specific mitochondrial respiratory chain diseases were 2.05 cases per 10(5) for Leigh syndrome, 0.68 per 10(5) for mitochondrial deoxyribonucleic acid (mtDNA) deletions and deletions-duplications, 1.59 per 10(5) for mtDNA depletions, and 0.45 per 10(5) for mtDNA point mutations. Leigh syndrome was the most frequent clinical syndrome. The estimates of the prevalences of mtDNA deletions, deletions-duplications, and point mutations set forth here are lower than in similar previous studies, whereas the estimate of the prevalence of mtDNA depletions is rather higher. Sixteen of these patients manifested phenotypic syndromes that have not been previously reported in association with mitochondrial respiratory chain diseases.
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Affiliation(s)
- Manuel Castro-Gago
- Departamento de Pediatría, Servicio de Neuropediatría Hospital 12 de Octubre, Madrid, Spain.
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141
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Crispim D, Canani LH, Gross JL, Tschiedel B, Souto KEP, Roisenberg I. The European-Specific Mitochondrial Cluster J/T Could Confer an Increased Risk of Insulin-Resistance and Type 2 Diabetes: An Analysis of the m.4216T > C and m.4917A > G Variants. Ann Hum Genet 2006. [DOI: 10.1111/j.1529-8817.2005.00249.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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142
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Crispim D, Canani LH, Gross JL, Carlessi RM, Tschiedel B, Souto KEP, Roisenberg I. The G1888A variant in the mitochondrial 16S rRNA gene may be associated with Type 2 diabetes in Caucasian-Brazilian patients from southern Brazil. Diabet Med 2005; 22:1683-9. [PMID: 16401312 DOI: 10.1111/j.1464-5491.2005.01702.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To compare the frequencies of the G1888A variant in the mitochondrial 16S rRNA gene between patients with Type 2 diabetes and non-diabetic control subjects from southern Brazil. METHODS We analysed 520 Type 2 diabetic patients (389 Caucasian- and 131 African-Brazilians) and 530 control subjects (400 Caucasian- and 130 African-Brazilians). DNA samples were amplified by polymerase chain reaction and digested with the RsaI enzyme. Variant frequency in patients and control subjects was compared using chi2 test, Fisher's exact test or odds ratio test. We also investigated the frequency of the G1888A variant in a subgroup of the patients with a maternal history of Type 2 diabetes plus two or more features of maternally inherited diabetes and deafness. RESULTS The 1888A allele does not seem to be associated with Type 2 diabetes in African-Brazilians (frequency of 3.8% in patients and 0.8% in control subjects; PFisher=0.213). However, in Caucasian-Brazilians, the 1888A allele was significantly associated with diabetes (12.3% in patients vs. 3.5% in control subjects; OR=3.881; 95% CI 2.106-7.164; P<0.001) and also with higher levels of insulin resistance. The majority of the patients carrying the 1888A allele did not have clinical features of maternally inherited diabetes and deafness. CONCLUSION The present study indicates the association of the mitochondrial G1888A variant with Type 2 diabetes and insulin resistance in Caucasian-Brazilian patients from southern Brazil. However, further studies are required to confirm its effects on mitochondrial function and the role of these effects on the pathogenesis of Type 2 diabetes.
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Affiliation(s)
- D Crispim
- Genetics Department, Universidade Federal do Rio Grande do Sul, and Endocrinology Division, Hospital de Clinicas de Porto Alegre, Rio Grande do Sul, Brazil
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143
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Lim S, Park KS, Kim MS, Cho BY, Lee HK. Relationship between various surrogate indices of insulin resistance and mitochondrial DNA content in the peripheral blood of 18 healthy volunteers. Mitochondrion 2005; 1:71-7. [PMID: 16120270 DOI: 10.1016/s1567-7249(01)00003-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2000] [Revised: 02/06/2001] [Accepted: 02/07/2001] [Indexed: 11/21/2022]
Abstract
Mutations or deletions of mitochondrial DNA (mtDNA) are associated with diabetes mellitus. In this study, we investigated the relationships between the mtDNA content in peripheral blood and surrogate indices of insulin resistance in 18 healthy young women (mean age 20.8 +/- 1.5 years). The mtDNA content was significantly correlated with the area under the curve of insulin during an oral glucose tolerance test (r = -0.622), the homeostasis model assessment for insulin resistance (r = -0.616), the ratio of fasting glucose to insulin concentration (r = 0.586) and the fasting insulin level (r = -0.552). Further study is warranted to elucidate the mechanism by which the mtDNA content is associated with insulin resistance.
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Affiliation(s)
- S Lim
- Department of Internal Medicine, Seoul National University College of Medicine, Chongno-gu, Seoul, South Korea
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144
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Lee YY, Park KS, Pak YK, Lee HK. The role of mitochondrial DNA in the development of type 2 diabetes caused by fetal malnutrition. J Nutr Biochem 2005; 16:195-204. [PMID: 15808323 DOI: 10.1016/j.jnutbio.2004.11.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 10/12/2004] [Accepted: 11/05/2004] [Indexed: 01/06/2023]
Abstract
Epidemiological studies have revealed strong and reproducible links between indices of poor fetal growth and susceptibility to the development of glucose intolerance and insulin resistance syndrome in adult life. To explain these associations, the thrifty phenotype hypothesis has been proposed. Mitochondrial DNA abnormalities have been known to cause insulin deficiency, insulin resistance and diabetes mellitus. In this review, we propose that mitochondrial dysfunction is a link between malnutrition during early life and disease in adult life. The potential mechanism for mitochondrial dysfunction will be focused on availability of the taurine and nucleotides, and imprinting on the genes.
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Affiliation(s)
- Yun Yong Lee
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea
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145
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Kazuno AA, Munakata K, Mori K, Tanaka M, Nanko S, Kunugi H, Umekage T, Tochigi M, Kohda K, Sasaki T, Akiyama T, Washizuka S, Kato N, Kato T. Mitochondrial DNA sequence analysis of patients with 'atypical psychosis'. Psychiatry Clin Neurosci 2005; 59:497-503. [PMID: 16048457 DOI: 10.1111/j.1440-1819.2005.01404.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although classical psychopathological studies have shown the presence of an independent diagnostic category, 'atypical psychosis', most psychotic patients are currently classified into two major diagnostic categories, schizophrenia and bipolar disorder, by the Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) criteria. 'Atypical psychosis' is characterized by acute confusion without systematic delusion, emotional instability, and psychomotor excitement or stupor. Such clinical features resemble those seen in organic mental syndrome, and differential diagnosis is often difficult. Because patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) sometimes show organic mental disorder, 'atypical psychosis' may be caused by mutations of mitochondrial DNA (mtDNA) in some patients. In the present study whole mtDNA was sequenced for seven patients with various psychotic disorders, who could be categorized as 'atypical psychosis'. None of them had known mtDNA mutations pathogenic for mitochondrial encephalopathy. Two of seven patients belonged to a subhaplogroup F1b1a with low frequency. These results did not support the hypothesis that clinical presentation of some patients with 'atypical psychosis' is a reflection of subclinical mitochondrial encephalopathy. However, the subhaplogroup F1b1a may be a good target for association study of 'atypical psychosis'.
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Affiliation(s)
- An-A Kazuno
- Laboratory for Molecular Dynamics of Mental Disorders, Brain Science Institute, RIKEN, Saitama, Japan
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146
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Kang D, Hamasaki N. Mitochondrial DNA in somatic cells: A promising target of routine clinical tests. Clin Biochem 2005; 38:685-95. [PMID: 15946663 DOI: 10.1016/j.clinbiochem.2005.04.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 04/07/2005] [Accepted: 04/21/2005] [Indexed: 10/25/2022]
Abstract
Alterations of mitochondrial DNA have long been considered only from a point of view of rare genetic disorders causing neuromyopathy. Recently, alterations of mitochondrial DNA have been found in so-called common diseases such as heart failure, diabetes, and cancer; some of these alterations are inherited, and some are generated and/or accumulated in somatic cells with age. Mitochondrial DNA is more vulnerable to alteration than is nuclear DNA. For example, mitochondria produce a large amount of reactive oxygen species as an inevitable byproduct of oxidative phosphorylation. Therefore, mitochondrial DNA is under much stronger oxidative stress than is nuclear DNA. In spite of the importance, it is much less elucidated in the mitochondrial genome than in the nuclear genome how the genome is maintained. In this review, we focus on maintenance of mitochondrial DNA in somatic cells and its clinical importance.
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Affiliation(s)
- Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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147
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Kanazawa A, Kawamura Y, Sekine A, Iida A, Tsunoda T, Kashiwagi A, Tanaka Y, Babazono T, Matsuda M, Kawai K, Iiizumi T, Fujioka T, Imanishi M, Kaku K, Iwamoto Y, Kawamori R, Kikkawa R, Nakamura Y, Maeda S. Single nucleotide polymorphisms in the gene encoding Krüppel-like factor 7 are associated with type 2 diabetes. Diabetologia 2005; 48:1315-22. [PMID: 15937668 DOI: 10.1007/s00125-005-1797-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 01/27/2005] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS Although genetic susceptibility plays an important role in the pathogenesis of type 2 diabetes, most of the genes that influence susceptibility to type 2 diabetes have yet to be identified. Krüppel-like transcription factors are known to play important roles in development and cell differentiation, and have recently been implicated in the pathogenesis of type 2 diabetes. The present study aimed to examine the associations of single nucleotide polymorphisms (SNPs) in genes encoding members of the Krüppel-like-factor (KLF) family with type 2 diabetes in a large cohort of Japanese subjects. METHODS We genotyped 33 SNP loci found in 12 KLF genes in subjects with type 2 diabetes and in subjects from the general population using the PCR-Invader assay. We also examined the effects of the overexpression of KLF7 on adipogenesis in 3T3-L1 cells. RESULTS We identified a significant association between an SNP in KLF7 and type 2 diabetes (A vs C: p=0.004 after Bonferroni's correction, odds ratio=1.59, 95% CI 1.27-2.00). The expression of Klf7 decreased in response to the differentiation of 3T3-L1 adipocytes, and the overexpression of KLF7 resulted in significant inhibition of adipogenesis in 3T3-L1 cells. CONCLUSIONS/INTERPRETATION These results indicate that the gene encoding KLF7 is a novel candidate for conferring genetic susceptibility to type 2 diabetes.
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Affiliation(s)
- A Kanazawa
- Laboratory for Diabetic Nephropathy, SNP Research Centre, Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
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148
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Knudsen TB, Green ML. Response characteristics of the mitochondrial DNA genome in developmental health and disease. ACTA ACUST UNITED AC 2005; 72:313-29. [PMID: 15662705 DOI: 10.1002/bdrc.20028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review focuses on mitochondrial biology in mammalian development; specifically, the dynamics of information transfer from nucleus to mitochondrion in the regulation of mitochondrial DNA genomic expression, and the reverse signaling of mitochondrion to nucleus as an adaptive response to the environment. Data from recent studies suggest that the capacity of embryonic cells to react to oxygenation involves a tradeoff between factors that influence prenatal growth/development and postnatal growth/function. For example, mitochondrial DNA replication and metabolic set points in nematodes may be determined by mitochondrial activity early in life. The mitochondrial drug PK11195, a ligand of the peripheral benzodiazepine receptor, has antiteratogenic and antidisease action in several developmental contexts in mice. Protein malnutrition during early life in rats can program mitochondrial DNA levels in adult tissues and, in humans, epidemiological data suggest an association between impaired fetal growth and insulin resistance. Taken together, these findings raise the provocative hypothesis that environmental programming of mitochondrial status during early life may be linked with diseases that manifest during adulthood. Genetic defects that affect mitochondrial function may involve the mitochondrial DNA genome directly (maternal inheritance) or indirectly (Mendelian inheritance) through nuclear-coded mitochondrial proteins. In a growing number of cases, the depletion of, or deletion in, mitochondrial DNA is seen to be secondary to mutation of key nuclear-coded mitochondrial proteins that affect mitochondrial DNA replication, expression, or stability. These defects of intergenomic regulation may disrupt the normal cross-talk or structural compartmentation of signals that ultimately regulate mitochondrial DNA integrity and copy number, leading to depletion of mitochondrial DNA.
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Affiliation(s)
- Thomas B Knudsen
- Department of Molecular, Cellular and Craniofacial Biology, School of Dentistry, Birth Defects Center, University of Louisville, Louisville, Kentucky 40202, USA.
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149
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Maeda S, Tsukada S, Kanazawa A, Sekine A, Tsunoda T, Koya D, Maegawa H, Kashiwagi A, Babazono T, Matsuda M, Tanaka Y, Fujioka T, Hirose H, Eguchi T, Ohno Y, Groves CJ, Hattersley AT, Hitman GA, Walker M, Kaku K, Iwamoto Y, Kawamori R, Kikkawa R, Kamatani N, McCarthy MI, Nakamura Y. Genetic variations in the gene encoding TFAP2B are associated with type 2 diabetes mellitus. J Hum Genet 2005; 50:283-292. [PMID: 15940393 DOI: 10.1007/s10038-005-0253-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 04/01/2005] [Indexed: 10/25/2022]
Abstract
To search a gene(s) conferring susceptibility to type 2 diabetes mellitus, we genotyped nearly 60,000 gene-based SNPs for Japanese patients and found evidence that the gene at chromosome 6p12 encoding transcription-factor-activating protein 2beta (TFAP2B) was a likely candidate in view of significant association of polymorphism in this gene with type 2 diabetes. Extensive analysis of this region identified that several variations within TFAP2B were significantly associated with type 2 diabetes [a variable number of tandem repeat locus: chi(2)=10.9, P=0.0009; odds ratio=1.57, 95% CI 1.20-2.06, intron 1+774 (G/T); chi(2)=11.6, P=0.0006; odds ratio=1.60, 95% CI 1.22-2.09, intron 1+2093 (A/C); chi(2)=12.2, P=0.0004; odds ratio=1.61, 95% CI 1.23-2.11]. The association of TFAP2B with type 2 diabetes was also observed in the UK population. These results suggest that TFAP2B might be a new candidate for conferring susceptibility to type 2 diabetes and contribute to the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Shiro Maeda
- Laboratory for Diabetic Nephropathy, SNP Research Center, The Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
| | - Shuichi Tsukada
- Laboratory for Diabetic Nephropathy, SNP Research Center, The Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Akio Kanazawa
- Laboratory for Diabetic Nephropathy, SNP Research Center, The Institute of Physical and Chemical Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Akihiro Sekine
- Laboratory for Genotyping, SNP Research Center, The Institute of Physical and Chemical Research, Kanagawa, Japan
| | - Tatsuhiko Tsunoda
- Laboratory for Medical Informatics, SNP Research Center, The Institute of Physical and Chemical Research, Kanagawa, Japan
| | - Daisuke Koya
- Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Hiroshi Maegawa
- Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Atsunori Kashiwagi
- Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | | | - Masafumi Matsuda
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kawasaki Medical School, Okayama, Japan
| | - Yasushi Tanaka
- Department of Medicine, Metabolism and Endocrinology, School of Medicine, Juntendo University, Tokyo, Japan
| | - Tomoaki Fujioka
- Department of Urology, Iwate Medical University School of Medicine, Iwate, Japan
| | - Hiroshi Hirose
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Takashi Eguchi
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Yoichi Ohno
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Christopher J Groves
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Wellcome Trust Centre for Human Genetics, Oxford, UK
| | | | - Graham A Hitman
- Centre of Diabetes and Metabolic Medicine, Bart's and The London, Queen Mary's School of Medicine and Dentistry, London, UK
| | - Mark Walker
- School of Clinical Medical Sciences, University of Newcastle, Newcastle, UK
| | - Kohei Kaku
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kawasaki Medical School, Okayama, Japan
| | | | - Ryuzo Kawamori
- Department of Medicine, Metabolism and Endocrinology, School of Medicine, Juntendo University, Tokyo, Japan
| | - Ryuichi Kikkawa
- Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Naoyuki Kamatani
- Institute of Rheumatology, Tokyo Women's Medical University, Tokyo, Japan
- Research Group for Personalized Medicine, SNP Research Center, The Institute of Physical and Chemical Research, Kanagawa, Japan
| | - Mark I McCarthy
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK
- Wellcome Trust Centre for Human Genetics, Oxford, UK
| | - Yusuke Nakamura
- Research Group for Personalized Medicine, SNP Research Center, The Institute of Physical and Chemical Research, Kanagawa, Japan
- Laboratory of Molecular Medicine, Human Genome Center, The Institute of Medical Science, University of Tokyo, Tokyo, Japan
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Tejerizo-García A, Hernández-Hernández L, Henríquez A, González-Rodríguez S, Ruiz M, Alcántara R, Martínez del Val M, Lanchares J, Tejerizo-López L. Enfermedades mitocondriales y gestación. CLINICA E INVESTIGACION EN GINECOLOGIA Y OBSTETRICIA 2005. [DOI: 10.1016/s0210-573x(05)73478-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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