Diabetes Mellitus with Mitochondrial Gene Mutations in Japan

Treating hyperglycaemia in a patient with maternally inherited diabetes and deafness with an inhibitor of dipeptidyl peptidase-4: a case report and two-year follow-up

Maternally inherited diabetes and deafness (MIDD) is a mitochondrial disorder with diverse characteristics, which make early diagnosis difficult. We report a case of 32-year-old woman with diabetes who was admitted due to weight loss and poor glycemic control. She had a history of gestational diabetes at age 26. Pancreatic function was evaluated by oral glucose tolerance. An ophthalmologic examination detected conjunctivitis and refractive errors and hearing tests were normal. The patient had a family of diabetes. Then we tested the patient and her first-degree relatives with a confirmed genetic mutation at position 3243 in the tRNA. After two years of treatment with linagliptin, both glycated hemoglobin and pancreatic function have shown improvement to some extent. Although MIDD is a rare form of diabetes, due to distinctive management and associated comorbidities it is important to diagnose.

Focal segmental glomerulosclerosis with a mutation in the mitochondrially encoded NADH dehydrogenase 5 gene: A case report

NADH dehydrogenase 5 (ND5) is one of 44 subunits composed of Complex I in mitochondrial respiratory chain. Therefore, a mitochondrially encoded ND5 (MT-ND5) gene mutation causes mitochondrial oxidative phosphorylation (OXPHOS) disorder, resulting in the development of mitochondrial diseases. Focal segmental glomerulosclerosis (FSGS) which had podocytes filled with abnormal mitochondria is induced by mitochondrial diseases. An MT-ND5 mutation also causes FSGS. We herein report a Japanese woman who was found to have proteinuria and renal dysfunction in an annual health check-up at 29 years old. Because her proteinuria and renal dysfunction were persistent, she had a kidney biopsy at 33 years of age. The renal histology showed FSGS with podocytes filled with abnormal mitochondria. The podocytes also had foot process effacement and cytoplasmic vacuolization. In addition, the renal pathological findings showed granular swollen epithelial cells (GSECs) in tubular cells, age-inappropriately disarranged and irregularly sized vascular smooth muscle cells (AiDIVs), and red-coloured podocytes (ReCPos) by acidic dye. A genetic analysis using peripheral mononuclear blood cells and urine sediment cells detected the m.13513 G > A variant in the MT-ND5 gene. Therefore, this patient was diagnosed with FSGS due to an MT-ND5 gene mutation. Although this is not the first case report to show that an MT-ND5 gene mutation causes FSGS, this is the first to demonstrate podocyte injuries accompanied with accumulation of abnormal mitochondria in the cytoplasm.

Biodistribution of Insulin Following Massive Insulin Subcutaneous Injection

A man in his 30s injected insulin several times into his abdomen and was found dead several hours later. Micropathological findings showed alveolar injury with hemorrhaging and cerebral parietal lobe nerve cell edema. Biochemical examinations showed that the blood insulin level was high, significantly so at the insulin injection sites. The blood glucose and C-peptide levels were low. The insulin level in the kidneys was low. In forensic medicine, a postmortem diagnosis of insulin subcutaneous injection is often difficult. When insulin injection is suspected, particularly high insulin levels can be expected at the insulin injection site, rather than in the blood.

Non-glycemic Adverse Effects of Insulin

Insulin is primarily considered for its glycemic effects in patients with diabetes. There are, however, non-glycemic adverse effects of insulin that may significantly impact patient health and interfere with glycemic control. Insulinogenic edema primarily occurs with rapid improvement in glycemic control either in patients with newly discovered diabetes or in patients with poorly-controlled diabetes. Insulin-induced sympathetic activation, vasodilation, changes in vascular permeability, and most importantly, sodium retention play significant etiologic roles in the development of edema. Clinically, it is usually self-limited, but significant complications can develop. Allergic reactions to all insulin preparations and various compounds used in insulin formulations with a wide range of severity have been reported. Frequently, changing the type of insulin or delivery method is sufficient, but more advanced treatments such as insulin desensitization and anti-IgE antibody treatment may be needed. Lipohypertrophy and lipoatrophy frequently develop with the overuse of injection sites. Lipohypertrophy can affect tissue insulin absorption and glycemic control.

Combination of disease duration-to-age at diagnosis and hemoglobin A1c-to-serum C-peptide reactivity ratios predicts patient response to glucose-lowering medication in type 2 diabetes: A retrospective cohort study across Japan (JDDM59)

AIMS/INTRODUCTION

Knowing the collective clinical factors that determine patient response to glucose-lowering medication would be beneficial in the treatment of type 2 diabetes. We carried out a retrospective cohort study to explore the combination of clinical factors involved in its therapeutic efficacy.

MATERIALS AND METHODS

The results of cohort studies retrieved using the CoDiC® database across Japan from January 2005 to July 2018 were analyzed based on criterion that using insulin therapy indicates severe type 2 diabetes.

RESULTS

A logistic regression analysis showed that age at diagnosis, disease duration, hemoglobin A1c (HbA1c) and serum C-peptide reactivity (CPR) at medication commencement were associated with the probability of insulin treatment. Receiver operating characteristic curve showed that these clinical factors predicted insulin treatment positivity with an area under the curve of >0.600. The area under the curve increased to 0.674 and 0.720 for the disease duration-to-age at diagnosis ratio and HbA1c-to-CPR ratio, respectively. Furthermore, area under the curve increased to 0.727 and 0.750 in the indices (duration-to-age ratio at diagnosis × 43 + HbA1c) and (duration-to-age ration at diagnosis × 21 + HbA1c-to-CPR ratio), respectively. After stratification to three groups according to the indices, monthly HbA1c levels during 6 months of treatment were higher in the upper one-third than in the lower one-third of patients, and many patients did not achieve the target HbA1c level (53 mmol/mol) in the upper one-third, although greater than fourfold more patients were administered insulin in the upper one-third.

CONCLUSIONS

The combination of disease duration-to-age at diagnosis and HbA1c-to-CPR ratios is a collective risk factor that predicts response to the medications.

Wolfram Syndrome: A Case Report and Review of Clinical Manifestations, Genetics Pathophysiology, and Potential Therapies

Background

Classical Wolfram syndrome (WS) is a rare autosomal recessive disorder caused by mutations in WFS1, a gene implicated in endoplasmic reticulum (ER) and mitochondrial function. WS is characterized by insulin-requiring diabetes mellitus and optic atrophy. A constellation of other features contributes to the acronym DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness). This review seeks to raise awareness of this rare form of diabetes so that individuals with WS are identified and provided with appropriate care.

Case

We describe a woman without risk factors for gestational or type 2 diabetes who presented with gestational diabetes (GDM) at the age of 39 years during her first and only pregnancy. Although she had optic atrophy since the age of 10 years, WS was not considered as her diagnosis until she presented with GDM. Biallelic mutations in WFS1 were identified, supporting a diagnosis of classical WS.

Conclusions

The distinct natural history, complications, and differences in management reinforce the importance of distinguishing WS from other forms of diabetes. Recent advances in the genetics and pathophysiology of WS have led to promising new therapeutic considerations that may preserve β-cell function and slow progressive neurological decline. Insight into the pathophysiology of WS may also inform strategies for β-cell preservation for individuals with type 1 and 2 diabetes.

The spectrum of clinical presentation, diagnosis, and management of mitochondrial forms of diabetes

Primary mitochondrial diseases refer to a group of heterogeneous and complex genetic disorders affecting 1:5000 people. The true prevalence is anticipated to be even higher because of the complexity of achieving a diagnosis in many patients who present with multisystemic complaints ranging from infancy to adulthood. Diabetes is a prominent feature of several of these disorders which might be overlooked by the endocrinologist. We here review mitochondrial disorders and describe the phenotypic and pathogenetic differences between mitochondrial diabetes mellitus (mDM) and other more common forms of diabetes mellitus.

Maternally inherited diabetes and deafness (MIDD): diagnosis and management

Maternally inherited diabetes with deafness is rare diabetes caused by a mitochondrial DNA defect. 85% of cases are associated with m.3243A>G mutation. It is important to diagnose this form of diabetes because of the unique management issues and associated comorbidities. A very strong family history of diabetes, deafness and presence of retinal dystrophy should prompt an investigation for MIDD. Microvascular complications out of keeping with duration of diabetes are another clue to the diagnosis. Retinal and renal manifestations of mitochondrial disease may be confused for diabetic complications. Glutamic acid decarboxylase (GAD) autoantibody negativity in a nonobese diabetic is another clue. Cardiac conduction defects and GDM may also raise suspicion as to the diagnosis. Recognizing this etiology of DM should promote family screening, genetic counseling, screening of associated comorbidities, avoidance of metformin, and cautious use of statins. We report a 77 years old lady with MIDD who was being followed up as insulin requiring type 2 diabetes. We then identified 5 more patients with MIDD in the same clinic. They all had A3243 mutation with characteristic clinical presentation. The pharmacological approaches discussed in the paper are unlikely to work in these patients as they were diagnosed late.

Pyrosequencing is an accurate and reliable method for the analysis of heteroplasmy of the A3243G mutation in patients with mitochondrial diabetes

Human mitochondrial DNA is a circular DNA molecule that encodes some of the proteins required for oxidative phosphorylation. Different mitochondrial DNA genotypes may coexist within a single cell, a condition known as heteroplasmy. An A-to-G transition at position 3243 of mitochondrial DNA (A3243G) can result in maternally inherited diabetes and deafness (mitochondrial diabetes). However, the commonly used methods of PCR restriction fragment length polymorphism and Sanger sequencing are neither sensitive nor reliable enough to detect this low level of heteroplasmy. Here, we developed a quantitative method based on pyrosequencing to analyze the heteroplasmy of the A3243G mutation in leukocyte DNA obtained from 83 persons of 15 unrelated pedigrees with mitochondrial diabetes. The accuracy and reliability of this method were also measured by comparing the results with those from high-resolution melting analysis, Sanger sequencing, and PCR restriction fragment length polymorphism with artificial heteroplasmy standard samples. The results showed that the accuracy of pyrosequencing was much higher than that of the other methods, and the limitation of heteroplasmy detection with this method reached 2%, based on our artificial control studies. An inverse correlation was found between the level of heteroplasmy and the age of the onset in our patients. This result suggested that the heteroplasmy of the A3243G mutation could become a significant prediction index for the onset of mitochondrial diabetes.

Refractory high output heart failure in a patient with primary mitochondrial respiratory chain disease

A 40-year-old man who was referred to our hospital due to dyspnea was found to have high output cardiac failure on Swan-Ganz catheterization. An endomyocardial biopsy revealed cardiomyocyte hypertrophy with a vacuolar structure consistent with mitochondrial disease (MD). The patient was discharged, then readmitted for high output cardiac failure with hypotension and hyperlactacidemia. Treatment with cardiopulmonary support and hemodiafiltration gradually improved his general condition, although it resulted in ischemic necrosis of the right leg. The hyperlactacidemia completely resolved after amputation, and the high output cardiac failure has not recurred for two years. High output cardiac failure is rare in MD patients and is related to myocardial abnormalities and hyperlactacidemia.

Maternally inherited diabetes and deafness in a North American kindred: tips for making the diagnosis and review of unique management issues

CONTEXT

Mutations in mitochondrial DNA are rare etiologies of adult-onset diabetes mellitus (DM) that merit identification to 1) prevent iatrogenic lactic acidosis, 2) prompt appropriate screening of affected patients and their families, 3) provide genetic counseling, and 4) provide an opportunity to investigate strategies for preventing diabetes.

OBJECTIVE

The objective of this study is to raise awareness of this rare form of adult-onset nonobese DM so that these patients are identified and provided with appropriate care.

PATIENTS

We describe a kindred in which four of seven siblings have adult-onset DM and sensorineural hearing loss with a confirmed genetic mutation at position 3243 in the tRNA. Two other siblings in this kindred demonstrate different phenotypes of mitochondrial disease.

INTERVENTION

The proband was treated with coenzyme Q10 for 1 yr.

OUTCOME MEASURES

Outcome measures included stress thallium exercise testing and audiometry testing.

RESULTS

After 1 yr of treatment of with coenzyme Q10, repeat stress thallium testing demonstrated improvement in the exercise tolerance of the proband from 7-12 min. Audiometry testing did not demonstrate a change in the rate of hearing decline.

CONCLUSION

Maternally inherited diabetes and deafness is a rare cause of DM that is important to diagnose because of the unique management issues and associated comorbidities. This work highlights clues to the identification of this rare monogenic form of adult- onset diabetes.

High prevalence of the COII/tRNA(Lys) intergenic 9-bp deletion in mitochondrial DNA of Taiwanese patients with MELAS or MERRF syndrome

The COII/tRNA(Lys) intergenic 9-bp deletion (MIC9D) of mitochondrial DNA (mtDNA) has been established as a genetic polymorphism for Asian-Pacific populations. We investigated whether this small mtDNA deletion is co-transmitted with human diseases such as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) and myoclonic epilepsy with ragged-red fibers (MERRF) syndromes. Forty unrelated Taiwanese families, including 12 families with MERRF and A8344G mtDNA mutation and 28 families with MELAS and A3243G mutation of mtDNA, respectively, were recruited in this study. In addition, 199 healthy subjects were recruited as control. We found that the frequency of occurrence of mtDNA with the MIC9D polymorphism in healthy subjects was 21% (41/199). However, the incidence of the MIC9D polymorphism was 67% (8/12) among the probands of all the families with MERRF syndrome (P = 0.001; OR = 8) and 39% (11/28) among the probands of the families with MELAS syndrome (P = 0.038; OR = 2). This finding indicates that the frequency of occurrence of mtDNA with the MIC9D polymorphism in patients with MERRF or MELAS syndrome is higher than that of healthy subjects. The prevalence of mitochondrial encephalomyopathies in relation to the MIC9D polymorphism of mtDNA in Taiwanese population is discussed.

Diabète et cytopathies mitochondriales : données anatomo-pathologiques

Maternal diabetes associated with neural deafness is designated as MIDD (maternal inherited diabetes and deafness); it is linked to a A3243G tRNA leucine gene mutation. The disease course is progressive and involvement of other systems is frequent. In most cases, macular pattern dystrophy is present. Muscular lesions are characteristic of mitochondrial myopathies. Mitochondrial abnormalities have also been observed in pancreas, heart, kidney, smooth muscle of the digestive tract with variable heteroplasmy levels. MIDD may present as a single syndrome or is part of MELAS or Kearns-Sayre syndrome.