Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Point mutation of mitochondrial DNA has been described in the blood from a MELAS patient. The 39-year-old patient developed progressive dementia, stroke-like episodes, heart conduction defect (Lown-Ganong-Levin syndrome) and cortical blindness. CT scan revealed brain atrophy and low density areas in the bilateral occipital lobes. Laboratory tests showed hyperglycemia and lactic acidosis. Muscle biopsy showed ragged red fibers on Gomori trichrome staining. He was clinically diagnosed as having MELAS and insulin-dependent diabetes mellitus. Onset of diabetes mellitus and MELAS was almost same. Family history showed his mother's brother and sisters had also insulin-dependent diabetes mellitus. We amplified the leucine (UUR) tRNA gene from the patient's blood with polymerase chain reaction (PCR) and analysed it by restriction enzyme analysis and sequencing. Genetic analysis showed A-to-G substitution at the nucleotide position 3243 in the leucine (UUR) tRNA gene. This substitution made a new restriction site Apa I. Mutant DNA coexisted with wild type DNA (heteroplasmy). It is shown that in some types of mitochondrial encephalomyopathies, especially patients of Kearns-Sayre syndrome (KSS), diabetes mellitus is often complicated. And in KSS patients insulin receptor in normal, but insulin secretion from beta cells of pancreas is decreased. In MELAS patients, however, has diabetes mellitus been reported to be rarely complicated and relationship between MELAS and diabetes mellitus is not done. As far as we know, two cases, including ours, with genetically diagnosed MELAS have been reported to have diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[MELAS associated with diabetes mellitus and point mutation in mitochondrial DNA]. 159 Nov 3

An A to G transition at nucleotide 3,243 in the tRNA(Leu(UUR)) gene of mitochondrial DNA (mtDNA) has been suggested to be the disease-related mutation for MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes). Recently, the same mutation has also been found in several pedigrees with maternally inherited diabetes mellitus and sensorineural deafness. We report here a family showing the association of deafness and diabetes mellitus, as the predominant clinical features, with this mutation. The mutation was detected by restriction-enzyme analysis of the relevant PCR-amplified segment of the mtDNA, in two generations. In this family, it is noteworthy that two members with the mutation had some symptoms of MELAS such as short stature, seizures and mental retardation and that one had no clinical symptoms though the mtDNA mutation was identified in his blood. The findings in this family demonstrate the diversity of clinical expression of the mtDNA mutation and suggest that a combination of sensorineural deafness and diabetes mellitus is only one typical presentation of the various phenotypic features caused by the 3,243 mutation.
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PMID:[Detection of a mutation in mitochondrial DNA in a family with sensorineural deafness and diabetes mellitus as the predominant clinical features]. 756 31

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.
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PMID:Diabetes mellitus carrying a mutation in the mitochondrial tRNA(Leu(UUR)) gene. 926 98

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.
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PMID:Clinical heterogeneity in two pedigrees with the 3243 bp tRNA(Leu(UUR)) mutation of mitochondrial DNA. 773 78

Mitochondrial diseases are heterogeneous and characterized by a primary defect of the mitochondrial energy output. Genetic defects of mitochondrial energy enzymes may be due to either nuclear DNA gene mutations or mitochondrial DNA (mtDNA) mutations. Among hereditary defects of nuclear-encoded mitochondrial enzymes, carnitine palmitoyltransferase II (CPT-II) deficiency and pyruvate dehydrogenase complex (PDHC) deficiency are of major interest to the neurologist. Several mutations in the CPT-II gene as well as in the X-linked E1 alpha subunit gene of PDHC have been reported and associated with different clinical phenotypes. mtDNA-related syndromes include mitochondrial encephalomyopathies (e.g. MELAS, MERRF, NARP, MIMyCa, etc.), 'pure' encephalopathies (e.g. LHON) and a few syndromes involving only non-neurological systems (e.g. Pearson's pancreas-bone marrow syndrome or diabetes mellitus). Three kinds of molecular lesions have been identified in mtDNA-related disorders: point mutations of protein-encoding mtDNA genes (mit- mutations), point mutations of mtDNA-tRNA genes (syn- mutations) and large-scale rearrangements of mtDNA (rho- mutations). Point mutations (mit- and syn+) are usually maternally inherited, while single large-scale mtDNA rearrangements are usually sporadic. Furthermore, mendelian traits leading to either qualitative or quantitative abnormalities of mtDNA (i.e. multiple mtDNA deletions and tissue-specific mtDNA depletion, respectively) are the first examples of genetic dysfunction of nuclear-mitochondrial communication. In most cases, the molecular detection of the known defects of mtDNA can be carried out by non-invasive techniques, thus making it an easy and relatively inexpensive procedure in the differential diagnosis of the mitochondrial disorders, a rapidly expanding area of clinical neurology.
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PMID:Mitochondrial diseases. 795 50

The molecular genetics of mitochondria relevant to NIDDM is described, because the mutations in mitochondrial DNA cause diabetes. The non-Mendelian genetics, including maternal inheritance, heteroplasmy, stochastic segregation are characteristic of mitochondrial gene. Since aging causes rapid loss of mitochondrial function, which results in the retardation of insulin secretion via ATP-sensitive K-channel. This loss is not caused by the age-dependent mutation in the mitochondrial DNA, but by a nuclear aging, perhaps accompanied by the shortening of telomere. This was shown by the cybrid experiment. The aged mitochondria in cytoplasts are transferred to immortal rho = cells (cells devoid of mitochondrial DNA) and restored its oxidative and transcriptional activities (J. Biol. Chem. 269:6878, 1994). Thus, the control mechanism of transcription in mitochondria has been analyzed. The genes for mitochondrial transcription factor (mtTF1) an MRP-RNA have been sequenced and their regulatory elements are found (BBRC 194:544, 1993 etc.) The mutations in mitochondrial DNA that cause diabetes have been found, and from the stochastic segregation of the heteroplasmic mutated mitochondrial DNA, we could explain why the MELAS mutation is concentrated in some tissue (J. Neurol. Sci. 120:174, 1993). Although there have been many reports on the mitochondrial mutations found in diabetic patients, we have to be careful on polymorphism (J. Biol. Chem. in press).
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PMID:[Molecular genetics of mitochondria and diabetes]. 798 85

We review the main features of human mitochondrial function and structure, and in particular mitochondrial transcription, translation, and replication cycles. Furthermore, some pecularities such as mitochondria's high polymorphism, the existence of mitochondrial pseudogenes, and the various considerations to take into account when studying mitochondrial diseases will also be mentioned. Mitochondrial syndromes mostly affecting the nervous system have, during the past few years, been associated with mitochondrial DNA (mt DNA) alterations such as deletions, duplications, mutations and depletions. We suggest a possible classification of mitochondrial diseases according to the kind of mt DNA mutations: structural mitochondrial gene mutation as in LHON (Leber's Hereditary Optic Neuropathy) and NARP (Neurogenic muscle weakness, Ataxia and Retinitis Pigmentosa) as well as some cases of Leigh's syndrome; transfer RNA and ribosomal RNA mitochondrial gene mutation as in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Strokelike Episodes) or MERRF (Myoclonic Epilepsy with Ragged Red Fibers) or deafness with aminoglycoside; structural with transfer RNA mitochondrial gene mutations as observed in large-scale deletions or duplications in Kearns-Sayre syndrome, Pearson's syndrome, diabetes mellitus with deafness, and CPEO (Chronic Progressive External Ophtalmoplegia). Depletions of the mt DNA may also be classified in this category. Even though mutations are generally maternally inherited, most of the deletions are sporadic. However, multiple deletions or depletions may be transmitted in a mendelan trait which suggests that nuclear gene products play a primary role in these processes. The relationship between a mutation and a particular phenotype is far from being fully understood. Gene dosage and energic threshold, which are tissue-specific, appear to be the best indicators. However, the recessive or dominant behavior of both the wild type or the mutated genome appears to play a significant role, which can be verified with in vitro studies.
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PMID:Mitochondrial DNA alterations and genetic diseases: a review. 799 80

Point mutations in the mitochondrial gene tRNA leucine(UUR) have been associated with maternally inherited mitochondrial myopathies including the MELAS syndrome (Mitochondrial Myopathy Encephalopathy Lactic acidosis and Stroke-like episodes). We describe a further mutation in tRNA leucine(UUR) in a patient with mitochondrial encephalomyopathy, pigmentary retinopathy, dementia, hypoparathyroidism and diabetes mellitus. The mutation was heteroplasmic in the proband's blood (30%) and muscle (76%); it was present at high levels in the proband's affected mother (50% in muscle), and at low levels (< 10%) in blood, muscle and fibroblasts of an unaffected sister. The mutation was not found in 121 normal controls or 35 other patients with mitochondrial disorders. The mutation is at a highly conserved position in the tRNA molecule, close to the 3,243 mutation which is associated with more than 80% of MELAS cases. Further more, both mutations lie within a possible transcriptional control region. This finding adds further support to the evidence that mutations in this region and in other mitochondrial tRNA genes may cause disease.
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PMID:A new point mutation associated with mitochondrial encephalomyopathy. 811 77

The clinical manifestations of mitochondrial encephalomyopathy are described in four generations of a single kindred. The age of onset of major neurological disturbance varied from 3-70 years. In some patients, deafness was the only manifestation; in others, recurrent bouts of status epilepticus associated with focal neurological deficits and headache, caused severe disability or death. Examples of all three adult forms of mitochondrial encephalomyopathy: MELAS, MERFF and Kearns Sayre syndrome, were represented within the kindred. Associated features included deafness, short stature, non-insulin-dependent diabetes mellitus, migraine, peptic ulceration and severe constipation. The nt 3243 A-G MELAS mutation was detected in two members of the kindred. This study highlights the diversity of clinical expression of a mitochondrial mutation within a single kindred.
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PMID:Mitochondrial encephalomyopathy: variable clinical expression within a single kindred. 835 Jan 9

A family with maternally-transmitted deafness and diabetes mellitus is described. Although the proband clinically exhibited MELAS-like symptoms such as sudden-onset cerebellar ataxia and weakness of the proximal portion of the limbs in addition to deafness and diabetes mellitus, the other three members of the family had only deafness and diabetes mellitus and no neurological manifestations. The analysis of mitochondrial DNA of the two members revealed an A-->G mutation of tRNA(leu(UUR)), a mutation commonly seen in patients with MELAS. According to the clinical histories and endocrinological investigations, the type of the diabetes mellitus in this family was considered to be IDDM, which may be attributed to the dysfunction of mitochondrial of the pancreas islet cells, resulting from the mutation of the mitochondrial DNA.
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PMID:[A family with MELAS whose main manifestations are maternally-transmitted deafness and diabetes mellitus]. 840 88


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