Masato Odawara

Mistyping frequency of the angiotensin-converting enzyme gene polymorphism and an improved method for its avoidance

Abstract A DD genotype of the angiotensin I-converting enzyme gene has been implicated in various diseases. However, genotype frequencies differ between previous reports, and data on the association of DD genotype with disease are sometimes conflicting. Although elimination of mistyping is of crucial importance, assessment of the accuracy of currently adopted typing methods has rarely been performed. Mistyping of the DD genotype is reported to occur by a conventional method with insertion/ deletion (I/D) flanking primers using polymerase chain reaction (PCR). We investigated whether currently adopted genotyping methods by PCR are reliable or not. We genotyped 248 patients by conventional PCR methods with I/D flanking primers with or without dimethyl sulfoxide (DMSO), and confirmed the DD genotype with insertion-specific primers with or without DMSO. Mistyping occurred frequently, not only in both methods without DMSO but also in a modified method with I/D flanking primers with inclusion of DMSO. Typing by these methods proved to lead to erroneous results more frequently than had been previously thought. To reduce mistyping frequency, initial PCR genotyping with I/D flanking primers with an inclusion of DMSO, followed by confirmation of the DD genotype by insertion-specific primers with DMSO, is recommended.

Association of the SNP-19 genotype 22 in the calpain-10 gene with elevated body mass index and hemoglobin A1c levels in Japanese.

BACKGROUND An association of variations in the calpain-10 gene (CAPN10) with type 2 diabetes was originally reported in Mexican Americans. However, some studies in other racial groups were contradictory. METHODS We studied the influence of genotypes and haplotype combinations (haplogenotypes) of CAPN10 on the metabolic traits in 286 Japanese subjects who visited a General Health Check-up Center. RESULTS As for single nucleotide polymorphism (SNP)-19, subjects with genotype 22 had higher body mass index (BMI) and hemoglobin A(1c) (HbA(1c)) levels than those with genotypes 11 and 12 (p=0.003 and p=0.024, respectively). In SNP-63, subjects with genotype 11 had higher BMI and HbA(1c) levels than those with genotypes 12 and 22 (p=0.003 and p=0.045, respectively). Subjects who had genotype 22 at SNP-19 always had genotype 11 at SNP-63. Subjects with haplogenotype 121/121 had higher BMI levels (p=0.021) and tended to have higher HbA(1c) levels (p=0.08) than those with other haplogenotypes. All things considered, SNP-19 genotype 22, which was composed of haplogenotype 121/121 and 121/221, had highest significance level of association with elevated HbA(1c) levels. SNP-43 did not affect metabolic traits in our subjects. Subjects with haplogenotype 112/121 rather showed lower BMI and HbA(1c) levels (p=0.016 and p=0.008) than those with all other haplogenotypes. CONCLUSIONS These results indicate the contribution of SNP-19 in CAPN10 to mild obesity and glucose intolerance in Japanese.

Corticosteroid-responsive diabetes mellitus associated with autoimmune pancreatitis: pathological examinations of the endocrine and exocrine pancreas.

Abstract: Histopathological changes of biopsied pancreata were examined in three diabetic patients with autoimmune chronic pancreatitis (ACP). We found intra‐ and periinsular mononuclear cell (MNC)—mainly CD8+ T cell—infiltration as well as MNC infiltration around the ductal cells. Islet β cell volume decreased significantly. Some ductal cells expressed insulin and insulin promoter factor‐1 concomitantly in the affected pancreas. These findings provide new insight toward understanding the pathological mechanisms of corticosteroid treatment‐responsive diabetes associated with ACP.

Radioiodinated Metaiodo-benzylguanidine Scintigraphγ for Pheochromocytoma

Radioiodinated metaiodobenzylguanidine (MIBG) scintigraphy is known for its high specificity in detecting pheochromocytoma and other tumors of neural crest origin. We describe herein the first case of

Diabetes With the 3243 Mitochondrial tRNALeu(UUR) Mutation: Characteristic neuroimaging findings

OBJECTIVE To investigate the basis of central nervous system dysfunction in diabetes associated with the 3243 mitochondrial tRNA mutation, we studied neuroimaging findings in patients with this disease. RESEARCH DESIGN AND METHODS We screened 205 diabetic patients. Those patients who had the 3243 mutation in leukocytes or muscle were enrolled. All the subjects underwent computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and N-isopropyl-p-[123I]iodoamphetamine ([123I]IMP) single-photon emission computed tomography (SPECT) of the brain. RESULTS None of the nine subjects with the 3243 mutation had the typical clinical picture of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, and none had neurological focal signs. CT or MRI revealed diffuse brain atrophy in three patients (33%) and cerebellar atrophy in one (11%). Abnormal high intensity areas were observed on MRI in five patients (56%). The overall prevalence of brain abnormalities was 56% (5 of 9) on CT and 78% (7 of 9) on MRI scans. MRA revealed no stenotic lesions. SPECT showed reduced accumulation of [123I]IMP in the right or left parieto-occipital region in eight patients (89%). CONCLUSIONS Reduced accumulation of [123I]IMP in the parieto-occipital cortex was found in a high proportion of our subjects on SPECT. This imaging finding might be characteristic of diabetes associated with the 3243 mitochondrial tRNA mutation and may be a sign of latent central nervous system dysfunction.

ENDOTHELIAL NITRIC OXIDE SYNTHASE GENE POLYMORPHISM AND CORONARY HEART DISEASE IN JAPANESE NIDDM

Dear Sir, Coronary heart disease (CHD) is one of the leading causes of death in Japan as well as in western countries. Many genes are suspected to be involved in its aetiology [1, 2]. Most however, remain to be clarified. Nitric oxide (NO) has vasodilatation effects, and inhibits smooth muscle cell proliferation and platelet adhesion, which lead to the development of atherosclerosis [3]. Endothelial NO is formed from l-arginine by constitutively expressed endothelial NO synthase (ecNOS). Though the l-arginine-NO pathway has been implicated in contributing to the protection from developing CHD [4], an association of ecNOS gene mutations or polymorphisms with CHD had not been proved to exist. Several genetic variations in the ecNOS gene have been reported, however, scarcely any have been reported to be associated with cardiovascular diseases to our knowledge [5]. Recently, a 27-base pair (bp) repeat polymorphism in intron 4 of the ecNOS gene (ecNOS 4a/a genotype) was shown to be associated with a smoking-dependent risk of coronary artery disease [6]. This genotype was also associated with a history of myocardial infarction. These observations raise the possibility that this polymorphism is associated with CHD in noninsulin-dependent diabetes mellitus (NIDDM), which is a potent risk factor for the development of atherosclerosis and CHD besides smoking. We investigated 164 unrelated Japanese patients with NIDDM (89 males/75 females) to see whether this polymorphism is associated with CHD. Of these, 42 (22 males/20 females) had a past history of acute myocardial infarction or had angiographically proven CHD with more than 75 % stenosis in at least one of the major coronary arteries (CHD + group), and 122 (67 males/55 females) who were apparently free from CHD on normal electrocardiograph at rest (CHD group). Age (CHD +; mean ± SD; 63.7 ± 8.8 years, CHD -: 61.8 ± 7.7 years: p = 0.17), sex (p = 0.78), body mass index (26.3 ± 4.2, 24.8 ± 4.0 kg/m: p = 0.053), duration of diabetes (14.1 ± 6.5, 12.7 ± 7.7 years: p = 0.32), systolic (152.0 ± 25.3, 144.0 ± 25.7 mm Hg: p = 0.08) and diastolic (91.0 ± 14.4, 86.1 ± 13.3 mm Hg: p = 0.07) blood pressure, proportion of smokers (0.24, 0.25: p = 0.93), serum total cholesterol (5.3 ± 1.0, 5.1 ± 1.0 mmol/l: p = 0.16), triglycerides (1.70 ± 1.20, 1.55 ± 0.95 mmol/l: Mann-Whiteys U-test, p = 0.56), Apo A1 (1.34 ± 0.28, 1.37 ± 0.26 g/l: p = 0.61), ApoB (1.17 ± 0.29, 1.02 ± 0.35 g/l: p = 0.08), HDL cholesterol (1.24 ± 0.30, 1.30 ± 0.35 mmol/l: p = 0.57) and HbA1c (8.19 ± 2.41, 8.76 ± 1.88 %, p = 0.61) were not significantly different statistically (t -test) between the two groups. The polymorphism was identified by polymerase chain reaction followed by electrophoresis on 6 % polyacrylamide gel. The used primers were, sense primer: 5 ¢-AGGCCCTATGGTAGTGCCTT-3 ¢ (5111-5130 bp), anti-sense: 5 ¢TCTCTTAGTGCTGTGGTCAC-3 ¢ (5530-5511 bp). Genetic determination (Table 1) revealed that among 42 CHD + patients, 31 had b/b (insertion +/insertion +) isoform and 11 had b/a (insertion +/insertion -) and none had a/a (insertion -/insertion -) isoform. Among 122 CHD patients, 103 patients had b/b isoform and 19 patients had b/a and none had a/a isoform. Neither the distribution of the ecNOS genotypes nor allele frequencies were significantly different between the CHD + and CHD groups. A/a genotype, which is associated with CHD in Caucasians, proved to be rare in the analysed Japanese patients. From these observations, we conclude that 27-bp repeat polymorphism in intron 4 of ecNOS gene is unlikely to play a major role in the pathogenesis of CHD among Japanese patients with NIDDM. And rarity of a/a genotype may contribute to the low incidence of CHD in Japanese patients with NIDDM.

Platelet glycoprotein IIIa PlA polymorphism and Japanese diabetic patients with coronary heart disease

associated with CHD in non-insulin-dependent diabetes mellitus (NIDDM) by analysing 211 unrelated Japanese patients with NIDDM. We determined the genotypes of 39 diabetic patients with CHD (23 men, mean [SD] age 62·7 [8·3] years), who either had a past history of acute myocardial infarction or had at least 75% stenosis in one or more major coronary branches on coronary angiography. We also analysed 172 patients with NIDDM (94 men, 55·7 [13·2] years) without apparent CHD, who had normal resting electrocardiography and no history suggestive of CHD. The serum values of total cholesterol, triglycerides, high-density lipoprotein cholesterol, apolipoprotein A1, apolipoprotein B, and haemoglobin A1C, and the percentage of smokers, were not significantly different between the two groups. We also analysed 11 diabetic patients with other macrovascular complications (seven with arteriosclerosis obliterans and four with large cerebral infarction) and 148 non-diabetic controls (44 men, mean age 45·7 [16·4]). By PCRrestriction fragment length polymorphism with endonuclease MspI and NciI, all patients with CHD, arteriosclerosis obliterans, or cerebral infarction proved to be Pl homozygoytes. Only a 37-year-old female with NIDDM without such macrovascular complications proved to carry Pl/Pl genotype (0·5% of NIDDM). She had been diabetic since 26 years of age and had proliferative diabetic retinopathy. Her parents and grandparents had NIDDM. However, no family members had CHD, to the patient’s knowledge. By screening non-diabetic people, this polymorphism proved to exist in only two of 148 participants (1·4%). However, neither of the 52-year-old and 55-year-old women carrying the Pl/Pl genotype, nor their family members had CHD. It has been suggested that many genes are involved in the pathogenesis of CHD, most of which still remain unknown. Though a strong association was observed in whites, no association between the Pl polymorphism and CHD was observed in Japanese diabetic patients. The Pl allele existed in only three of 370 Japanese people (0·8%) screened in this study. The extremely low prevalence of this polymorphism in Japanese compared with white people with (39·4%, 50%) or without CHD (19·1%, 26·7%) suggests an ethnic difference. In Japanese patients with or without NIDDM, the prevalence of CHD is much lower than in white counterparts. Environmental and behavioural factors have been suggested to be aetiologically important. However, low prevalence of CHD in Japanese seems partly due to ethnic differences in the genetic predisposition. Further studies are necessary, but Pl polymorphism is unlikely to be an important risk factor for CHD in Japanese diabetic populations. The extremely low prevalence of the Pl allele may contribute to the low incidence of CHD in Japanese.

Potentially Lethal Ileus Associated With Acarbose Treatment for NIDDM

be a normal finding in the elderly Serum calcium and phosphate were normal. The patient was fluid resuscitated with normal saline and treated with intravenous insulin and antibiotics. Her glucose level was brought within the normal range over 12 h. Her chorea resolved with the normalization of her glucose. To our knowledge, this is the first reported case of reversible choreoathetosis due to diabetes.

Absence of association between a mitochondrial DNA mutation at nucleotide position 3243 and schizophrenia in Japanese

M. Toru Tokyo Medical and Dental University, Japan Schizophrenia is a heterogeneous disorder. Although a genetic predisposition has been reported to exist, the genes involved in the pathogenesis of schizophrenia are largely unknown. Epidemiological studies have indicated that schizophrenia is more frequent in patients with impaired glucose tolerance than in the general population. The reason is unknown. Mitochondrial gene abnormalities have been reported to contribute to the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). About 1% of patients with NIDDM have an A →G mutation at nucleotide position (np) 3243 of the mitochondrial DNA (mtDNA) (Odawara et al. 1995), which is also present in patients with MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes). Mitochondria play an important role in normal functions of the brain, which consumes much energy and is thought to be susceptible to ATP shortage caused by mitochondrial dysfunction. In fact, impaired mitochondrial function is associated with degenerative diseases such as Parkinson’s disease and Alzheimer’s disease (Wallace 1992). Impairment of brain functions caused by mitochondrial dysfunction might also lead to mental disorders such as schizophrenia. We have encountered a case that suggested involvement of mitochondrial gene abnormalities in the pathogenesis of schizophrenia, mitochondrial myopathies and NIDDM (Odawara et al. 1997). These observations raise the possibility that mitochondrial dysfunction might play a part in the development of schizophrenia, and that the increased prevalence of NIDDM in schizophrenia might be partly due to mitochondrial gene abnormalities. LETTER TO THE EDITORS

Absence of association between the Gly40→Ser mutation in the human glucagon receptor and Japanese patients with non-insulin-dependent diabetes mellitus or impaired glucose tolerance

Abstract We investigated whether a G123→A mutation causing a Gly40→Ser substitution in exon 2 of the human glucagon receptor gene, which has been reported to be associated with non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) in France and Sardinia with a prevalences as high as 4.6% and 8.3%, respectively, is associated with Japanese patients with glucose intolerance. This mutation was not found in 242 unrelated Japanese patients with NIDDM or 23 with IGT by screening by the polymerase chain reaction-restriction fragment length polymorphism method. We also performed single-stranded conformational polymorphism analysis to search for new mutations in this gene associated with glucose intolerance. We found no mutations by examining all the 13 exons from 30 selected patients with NIDDM who had at least 2 diabetic first-degree relatives. These patients were also screened for the common polymorphism at codon 155 reported previously, but none were found to carry it. The absence of the mutation and polymorphism, which are common in French and Sardinian NIDDM or IGT patients, in Japanese indicates the existence of marked ethnic differences.