Importance of maternal history of non-insulin dependent diabetic patients

Clinical features of diabetes mellitus with the mitochondrial DNA 3243 (A-G) mutation in Japanese: maternal inheritance and mitochondria-related complications

Diabetes mellitus with the mitochondrial DNA 3243(A-G) mutation is reported to represent 0.5-2.8% of the general diabetic population. Since the characterization of diabetes with the mutation is still incomplete, we undertook a nation-wide case-finding study of genetically defined patients using questionnaires in Japan. One hundred and thirteen Japanese diabetic patients with the mutation were registered and analyzed. The patients had a high prevalence of maternal inheritance of diabetes and deafness, short and thin stature, and showed an early middle-aged onset of diabetes and deafness. Eighty-six percent of the patients required insulin therapy due to the progressive insulin secretory defect. Glucose intolerance of the mothers was associated with an early middle-aged onset of diabetes, reduction in the insulin secretory capacity, early requirement of insulin therapy, and increases in the daily insulin dose. The heteroplasmic concentrations of the 3243 mutation in leukocytes were low and declined with aging. The patients had advanced microvascular complications, and mitochondria-related complications such as cardiomyopathy, cardiac conductance disorders, neuromuscular symptoms, neuropsychiatric disturbance, and macular pattern dystrophy. Thus, this study has revealed that: (1) diabetes mellitus with the 3243 mutation is a subtype of diabetes mellitus with mitochondria-related complications; and (2) insulin secretory ability is more severely impaired in the patients whose mothers were glucose intolerance.

Excess maternal transmission and familial aggregation of Type 2 diabetes in Sri Lanka

INTRODUCTION

An excess of maternal transmission of Type 2 diabetes mellitus has been reported in Europid populations, but not in South India.

METHOD

A questionnaire-based survey was carried out in 1000 (502 male) people with Type 2 diabetes to establish whether there is an excess of maternal transmission and familial aggregation in a Sri Lankan population.

RESULTS

Mean age of onset was 47+/-12 (+/-S.D.) years and duration of diabetes was 9+/-7 years. Thirty-seven percent reported parents with diabetes, 46.9% had no parents with diabetes, 16.1% did not know the diabetes status of at least one parent and there was no diabetes in the other. Of the probands, 59.4% had at least one affected relative. When both parents' diabetes status was known and only one was affected, diabetes was more common among mothers (n = 156) than fathers (n = 125) of probands (P < 0.001). A further 54 probands had both parents with diabetes. Mean age of onset and duration of the disease among probands with parental diabetes was 43.1+/-(11.1) and 9.6+/-(6.8). In the previous generation, 21.2% of maternal grandmothers and 17.3% of maternal grandfathers in the maternal diabetes group and 4.8% of maternal grandmothers and 17% of maternal grandfathers in the paternal diabetes group had diabetes. Diabetes in siblings and children was more common in those with mothers who had diabetes (53.8% and 4.5%) when compared with those in whom fathers had diabetes (42.4% and 1.6%) (P < 0.0001 and P < 0.01).

CONCLUSION

Familial aggregation and excess maternal transmission were observed in people with Type 2 diabetes in Sri Lanka.

Determinants of the development of diabetes (maturity-onset diabetes of the young-3) in carriers of HNF-1alpha mutations: evidence for parent-of-origin effect

OBJECTIVE

To determine the distribution of the age at onset of diabetes (maturity-onset diabetes of the young-3 [MODY3]) and to identify determinants of the onset of diabetes in carriers of HNF-1alpha mutations.

RESEARCH DESIGN AND METHODS

Extended families (n = 104) with type 2 diabetes inherited in a dominant pattern were recruited and screened for diabetes-causing mutations in HNF-1alpha.

RESULTS

HNF-1alpha mutations cosegregated with diabetes in only 13 families, all with a mean age at onset <35 years. Insulin secretion was diminished or absent in mutation carriers (n = 101), and diabetes developed in 65% by age 25 years and in 100% by age 50 years. If the mutation was inherited from the mother, diabetes onset was very young in those exposed to diabetes in utero; 57 +/- 8% were affected by age 15 years as compared with 0.0% in those not exposed (P < 7 x 10(-6)). By age 25 years, the difference was reduced (85 +/- 6 and 55 +/- 12%, respectively; P = 0.02). If the mutation was inherited from the father, diabetes developed in 52 +/- 8% by age 25 years. Age at diagnosis was shown to be highly heritable (h(2) = 0.47, P = 0.003). When parent of origin was included in the analyses, the magnitude of genetic contribution increased markedly (h(2) = 0.91).

CONCLUSIONS

Mutations in HNF-1alpha accounts for diabetes in a small proportion of families with a dominant pattern of inheritance. Age at onset of diabetes in MODY3 families varied widely and was influenced by familial factors (including modifying genes) and parent of origin (whether a mutation carrier was exposed to diabetes in utero).

Mitochondrial diabetes: pathophysiology, clinical presentation, and genetic analysis

This study provides a compact overview on the most common form of the maternally inherited diabetes and deafness syndrome (MIDD) that associates with an A-G mutation in mitochondrial DNA at position 3243 in the tRNA(Leu,UUR) gene. The pathobiochemistry and pathophysiology is discussed. The mutation leads predominantly to a reduced insulin secretion by beta cells in response to glucose stimulation, however, without marked involvement of autoimmune processes as seen in type 1 diabetes mellitus. The underlying biochemical mechanism leading to beta cell dysfunction is discussed. Furthermore, the clinical presentation of the disease is summarized as are the methods to detect the A3243G mutation, particular in view of the often low levels of heteroplasm of the A3243G mutation.

Mitochondrial diabetes mellitus

This review discusses the current insight by which mutations in mitochondrial DNA (mtDNA) contribute to the development of particular disease states with emphasis on diabetes mellitus. Mitochondria are the power factories of the cells and produce ATP by oxidizing reducing equivalents via the respiratory chain. These reducing equivalents originate mainly from the citric acid cycle that also occurs within the mitochondria. Human mitochondria contain their own genetic material in the form of circular DNA that encodes for only a fraction of the mitochondrial components. The other mitochondrial components are nuclear encoded. Pathogenic mutations in mtDNA can affect the activity of the respiratory chain, thereby leading to the reduced generation of ATP. However, mitochondria not only produce ATP but they also regulate cytosolic concentrations of signaling molecules such as calcium and iron ions. The metabolic processes within mitochondria such as the citric acid cycle determine the concentration of metabolites that can also act as signalling molecules. Furthermore, the respiratory chain and mitochondrion-associated monoamine oxidase are major producers of reactive oxygen radicals. As a result, mutations in mtDNA can deregulate multiple processes within cells and the balance of this deregulation may contribute to the clinical phenotype.

Maternal transmission of diabetes

Type 2 diabetes mellitus represents a heterogeneous group of conditions characterized by impaired glucose homeostasis. The disorder runs in families but the mechanism underlying this is unknown. Many, but not all, studies have suggested that mothers are excessively implicated in the transmission of the disorder. A number of possible genetic phenomena could explain this observation, including the exclusively maternal transmission of mitochondrial DNA (mtDNA). It is now apparent that mutations in mtDNA can indeed result in maternally inherited diabetes. Although several mutations have been implicated, the strongest evidence relates to a point substitution at nucleotide position 3243 (A to G) in the mitochondrial tRNA(leu(UUR)) gene. Mitochondrial diabetes is commonly associated with nerve deafness and often presents with progressive non-autoimmune beta-cell failure. Specific treatment with Coenzyme Q10 or L-carnitine may be beneficial. Several rodent models of mitochondrial diabetes have been developed, including one in which mtDNA is specifically depleted in the pancreatic islets. Apart from severe, pathogenic mtDNA mutations, common polymorphisms in mtDNA may contribute to variations of insulin secretory capacity in normal individuals. Mitochondrial diabetes accounts for less than 1% of all diabetes and other mechanisms must underlie the maternal transmission of Type 2 diabetes. Possibilities include the role of maternally controlled environments, imprinted genes and epigenetic phenomena.

Can inaccuracy of reported parental history of diabetes explain the maternal transmission hypothesis for diabetes?

BACKGROUND

The mode of inheritance of type 2 diabetes mellitus is still under discussion. Several studies have suggested an excess maternal transmission, however, more recent studies could not always confirm these findings.

METHODS

We investigated the frequency of a maternal and paternal history of diabetes among diabetic and non-diabetic subjects and assessed the association between diabetes and a parental history of diabetes among participants of the MONICA Augsburg study. As an extension to previous studies, unknown parental status was taken into account.

RESULTS

Of the 542 diabetic probands, 25.3% reported a positive maternal history of diabetes and 10.9% reported a positive paternal history of diabetes. Among the 12,209 non-diabetic participants a positive maternal history was also more common than a positive paternal history (12.5% versus 7.1%). Conversely, an unknown paternal status was more common than an unknown maternal status in both groups (diabetic subjects: 27.9% versus 16.8%, non-diabetic subjects: 16.8% versus 8.4%). Adjusted odds ratios (OR) for the association between a parental history of diabetes and diabetes status were similar for a positive maternal (OR = 2.9, 95% CI : 2.3-3.6) and paternal history (OR = 2.8, 95% CI : 2.1-3.8) and for an unknown maternal (OR = 1.3, 95% CI : 1.0-1.8) and paternal history (OR = 1.5, 95% CI : 1.2-1.9).

CONCLUSION

Our findings do not support a strong excess maternal transmission of diabetes. Epidemiological biases and failure to account for 'don't know' responses may in part explain the previously observed predominance of a maternal history of diabetes.

Defining the genetic contribution of type 2 diabetes mellitus

Type 2 diabetes mellitus is a common multifactorial genetic syndrome, which is determined by several different genes and environmental factors. It now affects 150 million people world wide but its incidence is increasing rapidly because of secondary factors, such as obesity, hypertension, and lack of physical activity. Many studies have been carried out to determine the genetic factors involved in type 2 diabetes mellitus. In this review we look at the different strategies used and discuss the genome wide scans performed so far in more detail. New technologies, such as microarrays, and the discovery of SNPs will lead to a greater understanding of the pathogenesis of type 2 diabetes mellitus and to better diagnostics, treatment, and eventually prevention.

Low acute insulin secretory responses in adult offspring of people with early onset type 2 diabetes

The offspring of Pima Indians with early onset type 2 diabetes are at high risk for developing diabetes at an early age. This risk is greater among those whose mothers were diabetic during pregnancy. To define the metabolic abnormalities predisposing individuals in these high-risk groups to diabetes, we conducted a series of studies to measure insulin secretion and insulin action in healthy adult Pima Indians. In 104 normal glucose-tolerant subjects, acute insulin secretory response (AIR) to a 25-g intravenous glucose challenge correlated with the age at onset of diabetes in the mother (r = 0.23, P = 0.03) and, in multiple regression analyses, the age at onset of diabetes in the father (P = 0.02), after adjusting for maternal age at onset and after allowing for an interaction between these terms. In contrast, insulin action (hyperinsulinemic glucose clamp) did not correlate with the age at onset of diabetes in the parents. To determine whether early onset diabetes in the parents affected insulin secretion in the offspring across a range of glucose concentrations, responses to a stepped glucose infusion were measured in 23 subjects. Insulin secretion rates were lower in individuals whose mothers had developed diabetes before 35 years of age (n = 8) compared with those whose parents remained nondiabetic until at least 49 years of age (n = 15) (average insulin secretory rates: geometric mean [95% CI] 369 [209-652] vs. 571 [418-780] pmol/min, P = 0.007). Finally, the AIR was lower in individuals whose mothers were diabetic during pregnancy (n = 8) than in those whose mothers developed diabetes at an early age but after the birth of the subject (n = 41) (740 [510-1,310] vs. 1,255 [1,045-1,505] pmol/l, P < 0.02). Thus, insulin secretion is lower in normal glucose tolerant offspring of people with early onset type 2 diabetes. This impairment may be worsened by exposure to a diabetic environment in utero.

Importance of family history in type 2 black South African diabetic patients

OBJECTIVE

To assess the family history of diabetes in type 2 black South African diabetics with emphasis on the parental phenotype.

DESIGN

Prospective case-control study in which family histories were obtained from patients.

SETTING

Diabetic clinic of a provincial teaching hospital in the Transkei region of South Africa.

SUBJECTS

A total of 1111 type 2 diabetics attending the diabetic clinic and 687 controls.

MAIN OUTCOME MEASURES

History of diabetes in parents, siblings, maternal and paternal grandparents, aunts, and uncles.

RESULTS

Altogether 27.3% of diabetic subjects had a family history of diabetes compared with 8.4% in the control group (p<0.01). Among the group with positive family history 82.6% reported only one diabetic family member, while 17.4% reported at least two relatives; 6.6% had a diabetic relative from both maternal and paternal sides, and 87.8% had first degree relative with diabetes. Among them there was a significant maternal aggregation with 64.7% of patients having a diabetic mother compared with 27% who had a diabetic father (p<0.01). No maternal effect was observed among the second and third degree relatives. Patients with positive family history had an earlier onset of diabetes than those without family history (p<0.01).

CONCLUSION

These data suggest that type 2 diabetes is heritable in black South African diabetics. It is also likely that maternal influences may play an important part.

Analysis of a polycytosine tract and heteroplasmic length variation in the mitochondrial DNA D-loop of patients with diabetes, MELAS syndrome and race-matched controls

AIM

The T to C substitution at position 16189 nt of the human mitochondrial genome has been associated with the development of heteroplasmic length variation in the control region of mtDNA. Previous reports have suggested that this defect may be associated with the development of other pathogenic mtDNA mutations, including the diabetogenic A to G mutation in the tRNALEU(UUR). Recently the 16189 nt variant has also been associated with insulin resistance in British adult men. In order to investigate these associations further we studied 23 patients with the 3243 nt mutation, 150 patients with Type 2 diabetes and 149 non-diabetic controls.

METHODS

The region around 16189 nt was investigated by polymerase chain reaction-restriction fragment length polymorphism analysis and automated sequencing.

RESULTS

We find that the T to C substitution at 16189 nt is associated with heteroplasmic length variation only when the resultant polycytosine tract is not interrupted by a second mutation. There are no significant differences in the prevalence of the 16189 nt variant or heteroplasmic length variation between patients with the 3243 nt mutation, patients with Type 2 diabetes or race-matched normal controls.

CONCLUSIONS

We conclude that these variants are likely to represent normal polymorphisms and that previously reported associations should be treated with caution unless they can be replicated in other populations.

Mitochondrial gene expression in diabetes mellitus: effect of nutrition

Diabetes mellitus is a collection of genetic diseases that share a common phenotype: glucose intolerance. The genetic origins of this disease are being widely investigated. An estimated 0.19% of the population with diabetes has the disorder owing to one or more mutations in the mitochondrial genome. Diet can affect the expression of the genome as well as the function of its gene products. The antioxidant nutrients serve to protect this very vulnerable genome from oxidative damage. These nutrients may affect mitochondrial DNA transcription and nutrients that affect membrane fluidity affect the function of the gene products.

Diabetes and nutrition: the mitochondrial part

Diabetes mellitus is the most common genetic disease in the Western world today. It is the phenotype for >150 genotypes. Each of these genotypes is characterized by impaired glucose tolerance and impaired control of intermediary metabolism. There are many strains of mice and rats that can be used to study diabetes in its various forms. One of these is the BHE/Cdb rat, which mimics the human phenotype with a mutation in the mitochondrial (mt) DNA. The result of such mutation is a loss in metabolic control with respect to the role of the mitochondria in this control. This review addresses those aspects of control that are exerted by mt oxidative phosphorylation (OXPHOS). Diet can have both genomic and nongenomic effects on OXPHOS. The type of dietary fat influences the fluidity of the mt membranes and hence, mt function. The dietary fat effect depends on the genetic background of the consumer. Diabetes-prone BHE/Cdb rats with base substitutions in the mt ATPase 6 gene are more likely to be influenced by the diet effect on mt membrane fluidity than are normal rats. Vitamin A also affects mt function through an effect on mt gene expression. BHE/Cdb rats have a greater need for vitamin A than normal rats and supplemental vitamin A appears to influence OXPHOS.

A patient with type 2 diabetes mellitus associated with mutations in calcium sensing receptor gene and mitochondrial DNA

A 44-year-old female with familial hypocalciuric hypercalcemia (FHH) due to a homozygous missense mutation (Pro40Ala) in calcium sensing receptor (CaSR) gene has type 2 diabetes mellitus. The identical heterozygous mutation of CaSR gene was observed in consanguineous parents and all other family members examined except her two sisters. Many subjects with abnormal glucose tolerance were observed in this family, which is compatible with maternal inheritance. Mitochondrial function of complex I (NADH-coenzyme Q reductase) activity in cybrid cells between mitochondrial DNA (mtDNA)-deleted (rho(0)) HeLa cells and mtDNA from the proband was decreased by 35%. The proband has eight substitutions and among these 4833 A/G is a missense substitution in NADH dehydrogenase 2 gene and may probably be a major pathogenic mutation of impaired complex I activity. These results suggest that coexistence of nuclear gene and mtDNA mutations may have caused or modified the development of abnormal glucose tolerance in this family.

Influence of a familial history of diabetes on the clinical characteristics of patients with Type 2 diabetes mellitus

AIMS

To evaluate the roles of maternal and paternal diabetes and diabetes in relatives other than parents on the clinical characteristics in Type 2 diabetes mellitus.

METHODS

A total of 2,113 Type 2 diabetic patients were recruited, and those with diabetic mothers, diabetic fathers, diabetic relatives other than parents and no known diabetic relatives, were considered separately.

RESULTS

The prevalence of diabetes in the mother, father and other relatives was 25.5, 6.5 and 21.2%, respectively. No difference in the clinical characteristics was found in patients with diabetes in the mother or father. Patients with parental diabetes were significantly younger, with higher LDL-cholesterol, prevalence of retinopathy and lower age at diabetes diagnosis than those without familial diabetes; on multiple logistic regression, only age (P = 0.0003), age at diabetes diagnosis (P = 0.0014) (inverse association), and LDL-cholesterol (P = 0.030) remained significantly associated with parental diabetes. Patients with diabetic relatives other than parents displayed significantly higher total and LDL-cholesterol, prevalence of retinopathy and lower age at diabetes diagnosis that those with no known diabetic relatives; on multiple logistic regression, only age at diabetes diagnosis was inversely associated with diabetes in relatives other than parents (P = 0.013).

CONCLUSIONS

The data do not indicate a different influence of maternal and paternal diabetes on the clinical characteristics of Type 2 diabetic patients, while there is evidence that parental diabetes brings to an earlier onset of the disease and higher LDL-cholesterol values; the presence of diabetes in relatives other than parents constituted a small risk for earlier manifestation of the disease.

Mitochondrial DNA A3243G mutation in patients with early- or late-onset type 2 diabetes mellitus in Hong Kong Chinese

BACKGROUND AND OBJECTIVES

The mitochondrial DNA A to G mutation at nucleotide 3243 (mt3243) is associated with a subtype of diabetes characterized by maternal transmission and deafness. We have previously reported a 2.7% prevalence of this mutation in a cohort of young patients with either type 1 or type 2 diabetes. In this study, we aimed to confirm this finding by examining for the prevalence of this mutation in a large-scale study.

SUBJECTS AND METHODS

Nine hundred and six unrelated Chinese patients with type 2 diabetes and 213 nondiabetic controls were studied. The presence of mt3243 mutation was determined by polymerase chain reaction amplification and ApaI digestion.

RESULTS

This mutation was found in four of 133 (3.0%) patients with early onset (</= 40 years) diabetes who also had a positive maternal family history, and in one of 348 (0.3%) patients with late-onset (> 40 years) diabetes and no family history. Basal pancreatic beta-cell function, as assessed by fasting plasma C-peptide, was variable amongst mutation carriers, and did not correlate with the level of heteroplasmy of mutation.

CONCLUSIONS

In agreement with most studies, our results suggest that despite the high prevalence of positive maternal family history of diabetes amongst our type 2 diabetic patients, mt3243 mutation was not a major cause of diabetes in either early- or late-onset diabetic patients in Hong Kong. The role of other genetic, environmental and intrauterine factors needs further investigation.

Prevalence of a positive family history of type 2 diabetes in women with polycystic ovarian disease

The known association between insulin resistance and polycystic ovarian disease (PCOD) has been studied by determination of the prevalence of a positive family history of diabetes in a consecutive series of oligomenorrheic women with polycystic ovaries and eumenorrheic women with normal ovaries who served as controls. A significantly greater proportion of the families of the patients with PCOD had at least one member affected by type 2 diabetes (39.1% of the PCOD group and 7.6% of the controls; p < 0.001). Both obese (54.8%) and non-obese women (24.2%) with PCOD had an increased prevalence of type 2 diabetes within their families. Paternal and maternal family members affected were in similar proportions, there being no evidence of preferential transmission through the female line in this study. The increased prevalence of type 2 diabetes in the families of women with polycystic ovaries is further evidence for the association between PCOD and insulin resistance, and provides a possible explanation for the familial nature of the ovarian disorder.

Familial clustering of type II diabetes mellitus (DM) diagnosed under the age of 40 years in Yemen: Is it early-onset type II DM or maturity-onset diabetes of the young?

BACKGROUND

Clinical presentation of type II diabetes mellitus (DM) has frequently been observed at an early age in developing countries, probably as a result of genetic, epidemiological and demographic factors. This study aimed to investigate the pattern of familial clustering of type II DM in patients who developed clinical diabetes before the age of 40 years.

PATIENTS AND METHOD

The study involved family pedigrees, clinical assessments and laboratory investigations of 191 patients with type II DM, and 260 age-matched randomly selected non-diabetic controls.

RESULTS

The prevalence of type II DM was found to be statistically higher among parents (P<0.0001), fullsiblings (P<0.0001), half-siblings (P<0.001), uncles (P<0.01) and aunts (P<0.001) of the index patients, as compared to the corresponding relatives of nondiabetic controls. The odds ratio of the family history index (FHI), in association with type II DM in probands who had no family history of diabetes (FHI=0.0), was significantly negative (OR=0.34; 95% CI 0.23, 0.52; P<0.0001). At an FHI level of 0.5-1.0, there was a slight nonsignificant increase in odds ratio for diabetes (OR=1.53; 95% CI 0.95, 2.45; P=0.08). A higher level of FHI (A(3)1.5) was associated with a significant increase in odds ratio for diabetes (OR=3.75; 95% CI 2.13, 6.64; P<0.0001). The age-corrected relative risk of type II DM for the offspring of diabetic parents was found to be progressively increasing from a nonconsanguineous diabetic father (22%) or mother (26.5%), to nonconsanguineous conjugal diabetic parents (27%) and to the offspring of consanguineous single or conjugal diabetic parents (37.5%). On the contrary, the age-corrected relative risk for the offspring of nonconsanguineous and consanguineous nondiabetic parents was characteristically lower (14% for each). Maturityonset diabetes of the young (MODY) was suspected in 10 probands (5%), and early-onset type II DM in the offspring of conjugal diabetic parents in 16 probands (9%). The remaining 165 probands (86%) were unclassified due to lack of specific classification criteria.

CONCLUSION

The considerable familial clustering of type II DM diagnosed under the age of 40 years in this study population reflects the presence of a strong genetic component in its etiology. In addition, the development of early-onset type II DM was more likely associated with a consanguineous and/or conjugal diabetic parents and probably MODY subtype among a substantial number of patients. Epidemiological and demographic factors might have been implicated, especially in those with negative parental diabetic history.

Mitochondrial medicine--recent advances

Mitochondria contain the respiratory chain enzyme complexes that carry out oxidative phosphorylation and produce the main part of cellular energy in the form of ATP. Mitochondrial DNA (mtDNA) encodes essential subunits of the respiratory chain and is thus critical for maintaining cellular energy production. The first pathogenic mtDNA mutations were reported in 1988, and today more than 50 disease-causing mtDNA mutations have been identified. In addition, mtDNA mutations have been implicated in ageing and in common disorders such as diabetes mellitus, heart failure and Parkinson's disease. This review will summarize recent advances in the rapidly expanding field of mitochondrial medicine.

Early onset of diabetes mellitus associated with the mitochondrial DNA T14709C point mutation: patient report and literature review

We report a family in which a mother and son were affected with diabetes mellitus and myopathy characterized by ragged red fibers and suggestive of mitochondrial disease. Mitochondrial DNA (mtDNA) analysis of DNA isolated from peripheral blood showed a T-->C point mutation at nucleotide position 14709, in the transfer RNA gene for glutamic acid. We review the association of diabetes and mtDNA mutations. This child's case is unusual because of the early onset of diabetes, which is more typical of mtDNA deletions.

X-linked locus is responsible for non-insulin-dependent diabetes mellitus in the OLETF rat

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat has been recently established as the best model of non-insulin-dependent diabetes mellitus (NIDDM) with mild obesity. In this study, we found that the F1 progeny produced from the crosses of OLETF and F344 rats exhibit a reciprocal cross effect on NIDDM-relevant phenotypes, fasting and postprandial glucose levels and body weight, suggesting the existence of X-linked locus affecting susceptibility to NIDDM. We thus examined the linkage between 7 X-linked microsatellite markers and NIDDM-relevant phenotypes, using 160 (OLETF x F344)F2 progeny. Suggestive evidence for a X-linked locus affecting glucose levels at 120 min after glucose administration was found in a region near X-linked marker, DXMgh4. The identified locus also showed significant effects on fasting glucose levels and body weight.

Predominance of a maternal history of diabetes for patients with non-insulin-dependent diabetes mellitus. Implications for the intrauterine transmission of diabetes

In Europid populations, patients with non-insulin-dependent diabetes mellitus (NIDDM) are more than twice as likely to have a mother than a father with diabetes. We have examined this aspect in an Australian population. For this purpose records of 1,000 consecutive patients with NIDDM were reviewed. A history of diabetes was present in 193 mothers (19.3%) and in only 86 fathers (8.6%) (p < 0.0001). The predominance of maternal history of diabetes in patients with NIDDM is suggestive of a maternal transmission of this disorder. This metabolic tendency may develop due to an adverse intrauterine environment in women with undiagnosed gestational diabetes mellitus.

Demographic and clinical features of diabetes mellitus in 1095 Yemeni patients

The ever-increasing incidence of diabetes mellitus is a cause for growing public health concern in both developed and developing countries. In this study, we aim to explore the special demographic and clinical features of diabetes, as seen in a large sample of Yemeni patients, and to compare these features with those reported in other countries. All patients referred to our diabetic clinic over a five-year period were investigated according to a standardized protocol. Data was collected and fed into a personal computer with a software statistical package for analysis. The relative frequencies of clinical classes of diabetes were 10.5% for IDD, 58.6% for non-obese NIDDM; 26.2% for obese NIDDM, and 4.7% for IGT. In the IDDM class, the age-specific relative frequency rate showed a higher and earlier onset peak frequency in females than in males. Among NIDDM class, about 31% of patients were diagnosed under the age of 45 years, and only 12% were first diagnosed after the age of 65 years. Most NIDDM patients came from social classes I and II (professionals and intermediate professionals) and most IDDM patients came from social class IIIM (skilled manual). A positive family history of diabetes among first-degree relatives of index patients was observed in 33.7% of IDDM patients, in 30% of non-obese NIDDM patients, in 39.2% of obese NIDDM patients and 32% of IGT patients. Female NIDDM patients had a significantly higher mean body mass index (BMI) than males (P<0.0001). Hypertension was recognized in 24.2% of the diabetic population aged 20 to A(3) 65 years. Large vessel disease (LVD) was observed in 28% of patients, small vessel disease (SVD) in 45%, and peripheral neuropathy in 40.7%. Inadequate glycemic control was noticed during follow-up in the majority of patients. Diabetes mellitus in Yemen, especially NIDDM, is characterized by an earlier age at onset, and predominance of males and non-obese NIDM subclass. Other characteristics include moderate genetic susceptibility, inadequate glycemic control and high prevalence of chronic complications.

Screening for the mitochondrial DNA A3243G mutation in children with insulin-dependent diabetes mellitus

Since recent studies demonstrated the occurrence of the mitochondrial DNA (mtDNA) mutation A3243G in patients with adult-onset diabetes, an investigation was undertaken to determine the frequency of this mutation in a pediatric population with insulin-dependent diabetes mellitus (IDDM). DNA was extracted from peripheral blood of 270 pediatric patients with IDDM. The presence of the mtDNA A3243G mutation was screened for by minisequencing and mutation-specific ApaI endonuclease restriction after polymerase chain reaction (PCR) amplification of mtDNA. The A3243G mtDNA mutation was not found in any IDDM patients examined. This mutation is uncommon in children with IDDM from various ethnic and racial groups. Therefore, the contribution of the mutation to the pathogenesis of IDDM, if any, is minimal.

Non-insulin-dependent diabetes mellitus in childhood and adolescence

NIDDM in children and adolescents represents a heterogeneous group of disorders with different underlying pathophysiologic mechanisms. Most subtypes of NIDDM that occur in childhood are uncommon, but some, such as early onset of "classic" NIDDM, seem to be increasing in prevalence. This observed increase is thought to be caused by societal factors that lead to sedentary lifestyles and an increased prevalence of obesity. In adults, hyperglycemia frequently exists for years before a diagnosis of NIDDM is made and treatment is begun. Microvascular complications, such as retinopathy, are often already present at the time of diagnosis. Children are frequently asymptomatic at the time of diagnosis, so screening for this disorder in high-risk populations is important. Screening should be considered for children of high-risk ethnic populations with a strong family history of NIDDM with obesity or signs of hyperinsulinism, such as acanthosis nigricans. Even for children in these high-risk groups who do not yet manifest hyperglycemia, primary care providers can have an important role in encouraging lifestyle modifications that might delay or prevent onset of NIDDM.

Mitochondrial DNA mutations in Japanese detected by polymerase chain reaction--restriction fragment--single strand conformation polymorphism analysis

PCR-restriction fragment-SSCP (PCR-RF-SSCP) analysis of mitochondrial DNA by HhaI/HincII in Japanese revealed 46 polymorphic patterns. The determinations of nucleotide sequence of these 46 patterns revealed 56 mutations compared with the Cambridge Sequence.

Lactic acidosis and other mitochondrial disorders

The ability of mitochondria to oxidize substrates and generate energy is integral to normal homeostasis and to the ability of cells to survive in the face of impending energy failure. Lactic acidosis is a common and readily apparent biochemical marker for mitochondrial dysfunction. However, lactic acidosis represents only the most obvious example in which acquired or congenital abnormalities of mitochondrial oxidative phosphorylating capacity contribute to the pathobiology and phenotypic expression of a broad spectrum of clinical disorders. Consequently, interventions that improve mitochondrial function or prevent mitochondrial energy failure may have widespread therapeutic implications.

Non-insulin-dependent diabetes mellitus--a collision between thrifty genes and an affluent society

Non-insulin-dependent diabetes mellitus (NIDDM) is one of the most common non-communicable diseases in the world. It has become obvious that NIDDM is the result of a collision between thrifty genes and an affluent society. Genes predisposing to NIDDM might have been survival genes for our ancestors, helping them to store energy during long periods of starvation. When these genes are exposed to a sedentary lifestyle and high caloric intake typical to the Western world, they predispose to obesity and insulin resistance. NIDDM results when beta cells cannot compensate for insulin resistance by increasing insulin secretion. Therefore, at least two inherited defects can be expected in NIDDM, one causing obesity and insulin resistance and the other inability to increase insulin secretion. In reality there may be more inherited defects. It has become quite clear that diabetes cannot simply be divided into NIDDM and insulin-dependent diabetes mellitus (IDDM). The disease is more heterogeneous; unmasking this heterogeneity and identifying new subgroups of diabetes presents a challenge to modern molecular biology.

The significance of a positive family history in South African Indians with non-insulin-dependent diabetes (NIDDM)

A group of South African Indians with NIDDM participated in a study to evaluate the frequency of positive family histories of the disease and to determine the relative contribution of maternal or paternal genetic determinants. Information was elicited by means of an interview and recorded. Of the 1098 diabetic subjects studied 70% gave a positive family history of a first degree relative suffering from NIDDM. Three-generation transmission was recorded in 5.3% of the subjects. A significantly greater proportion of probands (40%) had a mother with NIDDM than those with a father (26%). A positive family history in an offspring was more common in female probands (10.6%) than males (5.5%). Twice as many probands with 3 generation transmission had a maternal grandmother suffering from NIDDM (2.5%) compared with those who had a paternal grandmother afflicted (1.2%) (P < 0.05), whereas the frequencies in the maternal (0.9%) and paternal (0.8%) grandfathers were similar. This study has highlighted, not only the high prevalence of a positive family history in South African Indians with NIDDM, but also a stronger maternal contribution to the putative gene responsible for the disease.

Difference in the influence of maternal and paternal NIDDM on pancreatic beta-cell activity and blood lipids in normoglycaemic non-diabetic adult offspring

The 75-g oral glucose tolerance test was performed in 38 normoglycaemic (World Health Organization criteria) non-diabetic volunteers, aged 31-40 years, of whom 20 had a non-insulin-dependent diabetic (NIDDM) mother and 18 had an NIDDM father. At the time of the study the offspring of NIDDM mothers had a somewhat higher body mass index (BMI) (males: 26.5 +/- 1.0 (mean +/- SEM), females: 27.5 +/- 1.5 kg/m2) than the offspring of NIDDM fathers (males: 23.4 +/- 0.9, females: 24.2 +/- 1.2 kg/m2). There was no difference in the time-course of glycaemia; however the serum concentrations of immunoreactive insulin (IRI), C-peptide and proinsulin were significantly higher in offspring of NIDDM mothers than in offspring of NIDDM fathers: area under the curve (AUC) serum IRI: 0.928 +/- 0.091 vs 0.757 +/- 0.056 nmol.l-1.h-1, p = 0.019; serum C-peptide: 6.379 +/- 0.450 vs 4.753 +/- 0.242 nmol.l-1.h-1, p = 0.004; serum proinsulin: 172 +/- 40 vs 51 +/- 7 pmol.l-1.h-1, p = 0.008). Serum IRI correlated with BMI, but C-peptide and proinsulin did not, and after accounting for BMI by covariance analysis they remained significantly higher in offspring of NIDDM mothers. In this group serum proinsulin was significantly higher in male than in female offspring (AUC serum proinsulin: 289 +/- 68 vs 77 +/- 27 pmol.l-1.h-1, P = 0.015). Male offspring of NIDDM mothers also had significantly higher serum triglyceride levels than females of the same group and than offspring of NIDDM fathers. The offspring (male and female) of NIDDM mothers had slightly lower serum apolipoprotein A-I levels than the offspring of NIDDM fathers. Significant correlations were found between serum triglycerides, HDL-cholesterol and apolipoprotein B, and serum concentrations of pancreatic beta-cell peptides, mostly in the offspring of NIDDM mothers; however, they did not display unequivocal association with gender within this group. The data are consistent with clinical observations of a greater risk of NIDDM transmission from the mother than from the father, and may suggest that male offspring are more exposed to this risk than female offspring.

Maternally inherited diabetes and deafness: a new diabetes subtype

Diabetes mellitus is a common disease with many forms of clinical expression. In addition, the development of diabetic complications is not only dependent on glycaemic control but also on individual factors which may be related to genetic heterogeneity. At present, multiple genetic factors are being recognized as contributing to the development of diabetes or possibly modulating its clinical expression. The purpose of this review is to give an overview of our current knowledge on a subtype of diabetes which is apparently caused by a single mutation in the mitochondrial DNA.

Molecular scanning of candidate mitochondrial tRNA genes in type 2 (non-insulin dependent) diabetes mellitus

Mitochondrial DNA (mtDNA) gene defects may play a role in the development of non-insulin dependent diabetes mellitus (NIDDM). In order to search for potentially diabetogenic mtDNA defects we have applied the technique of single stranded conformational polymorphism (SSCP) analysis to 124 patients with a history of NIDDM and 40 non-diabetic controls. No new heteroplasmic mutations were detected. However, a variety of homoplasmic variants were found in patients with NIDDM; some of these merit further investigation.

Genetic analysis of non-insulin dependent diabetes mellitus in the GK rat

Non-insulin dependent diabetes mellitus (NIDDM) is a major public health problem, but its aetiology remains poorly understood. We have performed a comprehensive study of the genetic basis of diabetes in the Goto-Kakizaki (GK) rat, the most widely used animal model of non-obese NIDDM. The genetic dissection of NIDDM using this model has allowed us to map three independent loci involved in the disease. In addition, we identify a major factor affecting body weight, but not glucose tolerance, on chromosome 7 and map a further 10 regions that are suggestive for linkage. We conclude that NIDDM is polygenic and fasting hyperglycaemia and postprandial hyperglycaemia clearly have distinct genetic bases.

Mitochondrial gene mutations in familial non-insulin-dependent diabetes mellitus in Taiwan

Mitochondrial gene mutations are found to cause certain forms of diabetes mellitus and related syndromes. To study the prevalence of mitochondrial gene mutations in subjects with non-insulin-dependent diabetes mellitus (NIDDM) in Taiwan, 23 pedigrees with multiple siblings affected with NIDDM were consecutively collected from patients living in northern Taiwan. The A-to-G mutation at position 3243 np in the tRNA Leu gene and the mutation at position 8344 were screened by PCR-RFLP methods and confirmed by direct DNA sequence analysis. Among 23 NIDDM pedigrees, one pedigree was found to carry the 3243 np mutation. There was no 8344 np mutation in this series. Clinical features of this pedigree were consistent with mitochondrial disease in terms of maternal transmission, relatively early onset, non-obesity, insulin-requirement and association with hearing impairment. There was no correlation between the degree of heteroplasmy of mitochondrial gene mutation in leukocyte DNA and clinical severity. We conclude that a mitochondrial gene defect is an important genetic factor in familial cases with NIDDM in Taiwan.

Mitochondrial diabetes mellitus: a review

We review the relationship between various types of mitochondrial DNA mutations and the prevalence as well as the pathobiochemical and clinical features of mitochondrial diabetes mellitus. An A to G transversion mutation in the tRNA(Leu(UUR)) gene is associated with diabetes in about 1.5% of the diabetic population in different countries and races. Phenotypically this type of mitochondrial diabetes is combined with deafness in more than 60% and is clinically distinguishable with respect to several characteristics from the two idiopathic forms of diabetes. The underlying pathomechanism is probably a delayed insulin secretion due to an impaired mitochondrial ATP production in consequence of the mtDNA defect.

Excess maternal history of diabetes in Caucasian and Afro-origin non-insulin-dependent diabetic patients suggests dominant maternal factors in disease transmission

We examined the records of 2576 patients with non-insulin-dependent diabetes mellitus (NIDDM) and categorised them according to race and family history of diabetes. Family history of diabetes is known to play an important role in the development of NIDDM, and a maternal history is thought to be most influential. We found that a maternal history of diabetes was present in 60% of Caucasian and West Indian patients with a parental history of diabetes, whereas in Asian patients the figure was only 34%. Asian men were also more likely to have a father with diabetes. This anomaly may be due to cultural differences in the reporting of the disease. Our data support the dominant maternal role in the development of NIDDM in their offspring and suggest an under-reporting of NIDDM in Asian females.

Screening for mtDNA diabetes mutations in Pima Indians with NIDDM

More than half of the Pima Indians over age 35 years have non-insulin-dependent (type II) diabetes mellitus (NIDDM). Extensive data indicate the importance of maternal diabetes in determining their risk for diabetes. Generally, the risk of having NIDDM is higher in patients with affected mothers than affected fathers. This has been attributed to intrauterine factors, but recently mitochondrial inheritance has been raised as an alternative hypothesis. In other populations, several families and individuals with diabetes due to a mitochondrial DNA point mutation at nucleotide 3243 in the tRNA(leu(UUR)) gene have been described, as has one family with a 10.4 kb mitochondrial DNA duplication/deletion. We tested whether these specific mitochondrial gene mutations could explain a portion of the excess maternal transmission seen in the Pima Indians. Mitochondrial DNA obtained from blood lymphocytes of 148 Pima Indians with NIDDM was screened both for the point mutation at nt 3243, and the 10.4 kb duplication/deletion. Neither of these mutations was detected, and although a small proportion of the excess maternal transmission in Pima Indians could still be due to yet undescribed mitochondrial mutations or imprinted nuclear genes, our data support the role of the intrauterine environment in this population.

Frequency of diabetes in family members of probands with non-insulin-dependent diabetes mellitus

OBJECTIVES

To describe the prevalence of known diabetes in a multi-ethnic community in South Auckland, New Zealand, in relation to family history of diabetes and past history of diabetes in pregnancy.

DESIGN

A cross-sectional, household survey comparing ascertainment with local general practice diabetes registers where they existed.

SETTING

An inner-city community with a high proportion of Maori, Pacific Islands people and Europeans.

SUBJECTS

A total of 55,518 residents (91% response). Comparison with diabetes registers showed 91% ascertainment of known diabetic residents. More detailed interviews with 176/214 (82%) Europeans, 286/336 (85%) Maori and 495/585 (85%) Pacific Islands people with known diabetes. Fifty subjects had insulin-dependent diabetes mellitus on clinical criteria and were excluded from analyses.

MAIN OUTCOME MEASURES

Prevalence of diabetes.

RESULTS

Those with non-insulin-dependent diabetes mellitus were more likely to have a diabetic mother than father (Europeans, 21.7% vs. 9.9%; Maori, 17.6 vs. 11.4%; Pacific Islands, 15.7 vs. 5.3%). Diabetic women had a similar likelihood of having a diabetic father as diabetic men but were 1.84 times as likely to have a diabetic mother (95% CI, 1.27-2.69). Diabetic women with past diabetes in pregnancy had 2.05 (95% CI, 1.01-4.15) times the chance of a diabetic offspring as women who had not had past diabetes in pregnancy, who in turn had 2.69 (95% CI, 1.17-6.18) times the likelihood of having a diabetic offspring as diabetic men.

CONCLUSIONS

The mother is a more important conduit for inheritance of diabetes than the father in these three ethnic groups. A history of diabetes in pregnancy confers an extra risk to the offspring above this usual maternal excess.

Is there an excess in maternal transmission of NIDDM?

Family studies have demonstrated that there is a strong genetic component to the aetiology of non-insulin-dependent diabetes mellitus (NIDDM), although the mode of inheritance is unknown. A number of recent family history studies, including one in Mexican Americans, have suggested that there is an excess of maternal transmission of NIDDM. Family history studies are subject to various types of bias, however, and the potential for bias in many of these studies has not been thoroughly evaluated. We therefore tested the hypothesis that diabetes is more likely to be transmitted from mothers than from fathers using data collected from a large family study of low-income Mexican Americans in San Antonio, Texas. The parents and offspring from 318 different nuclear families attended our medical clinic, where they received a 2-h oral glucose test. Diabetes was diagnosed on the basis of World Health Organization criteria. The sibships were classified into diabetic sibships (at least one sibling in the sibship was diabetic; n = 54) and non-diabetic siblings (no diabetic siblings; n = 264). The prevalence of diabetes among mothers of diabetic siblings was 61.4% (27 of 44) compared to 64.3% (18 of 28) among fathers of diabetic siblings (rate ratio = 0.95; 95% confidence interval; 0.51-1.84). For the non-diabetic sibships, the prevalence of diabetes was 31.7% (78 of 246) and 28.9% (37 of 128) among mothers and fathers, respectively (rate ratio = 1.09; 95% confidence interval: 0.73-1.67). These data provide no evidence for an excess maternal transmission of diabetes in Mexican Americans.

Maternally inherited diabetes mellitus: the role of mitochondrial DNA defects

Several studies have shown a consistent maternal effect in the transmission of Type 2 diabetes (NIDDM). The mitochondrial encephalomyopathies are a group of diseases characterized by maternal inheritance and a variety of mitochondrial DNA defects. Diabetes is a feature of some of these disorders and therefore the hypothesis arose that mitochondrial DNA mutations might play a role in patients with diabetes but no other features of neurological disease. Recent studies have confirmed that a specific point mutation in the gene encoding the mitochondrial tRNA for leucine segregates with diabetes and nerve deafness in families from the UK, Holland, France and Japan. Mitochondrial gene deletions have also been reported. Affected subjects present with progressive insulin deficiency and may fall into the broad classifications of either Type 1 (IDDM) or Type 2 diabetes (NIDDM). Future studies are aimed at searching for other mitochondrial gene defects in diabetes and attempting to explain the mechanism of hyperglycaemia by the development of phenotypic expression systems. Although an exciting development in the genetics of diabetes, currently described mitochondrial mutations do not fully explain the maternal effect in the transmission of Type 2 diabetes.

Diabetes mellitus carrying a mutation in the mitochondrial tRNA(Leu(UUR)) gene

We screened 214 Japanese NIDDM (non-insulin-dependent) diabetic patients with a family history of diabetes for mutations in the mitochondrial tRNA(Leu(UUR)) gene using polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. Six patients were identified as having an A to G transition at position 3243 (3243 mutation), but no patients were detected with a T to C transition at position 3271, in the mitochondrial tRNA(Leu(UUR)) gene. These two mutations were not present in 85 healthy control subjects. It was disclosed that the patients' mothers were also affected by diabetes mellitus in five of the six cases. In these six affected patients, the 3243 mutation shows variable phenotypes, such as the degree of multiple organ involvement, intrafamilial and interfamilial differences in disease characteristics, and the degree of the involvement of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) phenotype. Endocrinological examinations revealed that those diabetic patients with the 3243 mutation show not only beta-cell dysfunction, but also a defect in alpha-cell function, which is considered characteristic of diabetes with the 3243 mutation. When compared with 50 selected diabetic control subjects without the 3243 mutation, whose mothers, but not fathers, were found to have diabetes, it was established statistically that those with the 3243 mutation possess the following clinical characteristics; 1) the age of diabetes onset is lower, 2) they have lean body constitutions, and 3) they are more likely to be treated with insulin than control subjects. We suggest that diabetes with the 3243 mutation possesses phenotypes distinct from those in common forms of diabetes.

Clinical heterogeneity in two pedigrees with the 3243 bp tRNA(Leu(UUR)) mutation of mitochondrial DNA

We studied two pedigrees with a mutation at the nucleotide 3243 of mitochondrial DNA (mtDNA). The proband from the first pedigree had clinically defined MELAS plus maternally transmitted insulin-dependent diabetes mellitus (IDDM). The propositus of the other pedigree had exercise intolerance, lactic acidosis and ragged-red fibers (RRF). In the first pedigree, both the mother and the sister's proband harbored the point mutation in their muscle. The mother had 40% of mutant mitochondrial genomes and the sister 70%. In the second pedigree, the mutation was present in both muscle and blood from the proband as well as in blood from all other members studied. Proportion of mutant mtDNA was 90% in muscle and ranged from 40% to 90% in blood.

Maternally inherited diabetes and deafness (MIDD): a distinct subtype of diabetes associated with a mitochondrial tRNA(Leu)(UUR) gene point mutation

We have recently described a mitochondrial DNA (mtDNA) point mutation at np 3243 in the tRNA(Leu)(UUR) gene in a large Dutch pedigree with maternally inherited diabetes mellitus and deafness (MIDD) illustrating the importance of mitochondrial function in maintenance of a proper glucose homeostasis. In this review we will focus on the prevalence of the mtDNA mutation at np 3243 in diabetic populations, as well as postulate some working models for its pathogenicity.