Restriction fragment length polymorphism of the insulin gene region in Japanese diabetic and non-diabetic subjects

Summary A polymorphic locus flanking the 5 end of the insulin gene was studied in 154 unrelated Japanese diabetic and nondiabetic subjects. A predominance of the small allele was found with the following frequency: of 64 nondiabetic subjects, only 3 of 128 alleles were of the large class (2%); none of 78 alleles were of the large class in 39 Type 1 (insulin-dependent) diabetic subjects, and 4 of 102 alleles (4%) were of the large class in 51 Type 2 (non-insulin-dependent) diabetic subjects. The very low frequency of large allele may relate to the lower prevalence of atherosclerosis in Japanese. However, this possibility requires further examination.     

High frequency of class 3 allele in the human insulin gene in Japanese Type 2 (non-insulin-dependent) diabetic patients with a family history of diabetes

Summary The restriction fragment length polymorphism in the 5 flanking region of the human insulin gene was studied in 155 nonobese Japanese subjects. The subjects consisted of 36 Type 2 (non-insulin-dependent) diabetic patients with a family history of diabetes mellitus, 42 Type 2 diabetic patients without a family history of diabetes, 42 Type 1 (insulin-dependent) diabetic patients, and 35 healthy volunteers who served as control subjects. It was demonstrated that, in Japanese healthy subjects and diabetic patients, the incidence of the insertion into 5 flanking region of the insulin gene was found to be significantly lower (p<0.05) than those in Caucasians and other races already investigated. Even though the class 3 gene allelic frequency in Type 2 diabetic patients without a family history of diabetes (0.060) was not higher than that in healthy subjects (0.014), in nonobese Type 2 diabetic patients with a family history of diabetes the allelic frequency of the inserted class 3 gene (0.111) was found to be significantly higher (p<0.02) than that in control subjects. These data suggest that the insulin gene polymorphism relates to the aetiology of diabetes mellitus.     

Restriction fragment length polymorphisms at the GLUT4 and GLUT1 gene loci in type 2 diabetes.

Inherited abnormalities of the glucose transporters could explain many of the pathophysiological features of Type 2 diabetes including the strong familial predisposition to the disease. Previous studies have suggested a possible association between an allele of an Xba1 restriction fragment length polymorphism (RFLP) at the GLUT1 gene locus and Type 2 diabetes in Caucasian and Japanese subjects. In order to test this hypothesis further, population association studies were performed at the Xba1/GLUT1 and Kpn1/GLUT4 gene loci employing a group of diabetic patients with a strong family history for the disease. The frequencies of the two alleles at the GLUT1 locus were 0.28 and 0.72 in diabetic patients and 0.31 and 0.69 in control subjects. At the GLUT4 locus, the two alleles had frequencies of 0.24 and 0.76 in diabetic patients and 0.25 and 0.75 in control subjects. These differences were not statistically significant. The present study does not support the hypothesis that genetic variation within the GLUT1 or GLUT4 gene loci may be responsible for familial susceptibility to Type 2 diabetes.     

胰岛素受体底物1基因Gly972Arg多态性与2型糖尿病不相关

目的：探讨中国汉族人群胰岛素受体底物1（IRS－1）基因Gly972Arg多态性与2型糖尿病的关系。方法：选取102例2型糖尿病患者及102例糖耐量正常的患者配偶进行对照研究，应用聚合酶链反应－－限制性片断长度多态性的方法进行胰岛素受体底物1基因Gly972Arg多态性位点基因型检测。结果：IRS－1基因Gly972Arg突变频率在病例组和对照组均为2％，明显低于白人。结论：在中国汉族人群中，IRS－1基因Gly972Arg突变不是2型糖尿病的主要致病因素。     

HLA Gene analysis in a Japanese family with hypertrophic cardiomyopathy by restriction fragment length polymorphism

Summary A large Japanese family with hypertrophic cardiomyopathy (HCM) was examined (n = 61). Ten of 14 affected family members who showed HCM on the basis of electrocardiography and two-dimensional echocardiography were subjected to human leukocyte antigen (HLA)-A,B,C typing by the lymphocyte cytotoxicity test and D, DR typing by restriction fragment length polymorphism (RFLP). As control, the HLA genotype of 14 non-affected family members was analyzed. HLA typing of the affected subjects with HCM revealed a very close association (67%) of HLA-DR (4w8) among A,B,C,D and DR. However, the LOD scores of HLA-DR4 and -DR w8 were 0.693 ( = 0.35) and 0.642 ( = 0.30) respectively. These data suggest that HLA-loci, analyzed on the basis of RFLP, may not be related with familial HCM with or without obstruction.     

HLA-DQ beta-chain restriction fragment length polymorphism as a risk marker in Type 1 (insulin-dependent) diabetes mellitus: a Finnish family study

Summary Finnish Type 1 (insulin-dependent) diabetic families were analysed for HLA-DQ beta-chain polymorphism using a short intron-specific probe. A simple hybridization pattern was obtained in which all fragments were associated significantly with Type 1 diabetes. The simultaneous presence of two different risk markers, the allelic 12-kilobase and 4-kilobase fragments were strongly associated with Type 1 diabetes since 50% of the patients had this combination compared with only 2% of the control subjects. The cosegregated 7.5/3.0 kilobase fragments, which were associated with HLA-DR2 and DRw6 were not detected among the diabetic patients but were present in 48% of the control subjects. Our results provide further support for the location of susceptibility determining factors in the HLA-DQ gene area. The clear-cut, simple restriction fragment length polymorphism pattern obtained here, which bears a resemblance to a two allelic system, therefore makes this method applicable for estimating the risk of Type 1 diabetes at the population level.     

DNA restriction polymorphisms of the apolipoprotein AI-CIII-AIV gene cluster: a genetic determinant of atherosclerosis in type 2 (non-insulin-dependent) diabetes mellitus.

The presence of polymorphic restriction sites (S2, M2, P2) of the apolipoprotein AI-CIII-AIV gene cluster for the respective Sst1, Msp1, and Pst1 enzymes was assessed after hybridization with a radiolabelled apolipoprotein AI gene probe in 64 Type 2 diabetic patients and 67 healthy control subjects, all Europids. Twenty-two diabetic patients showed evidence of ischaemic heart disease or macrovascular arteriopathy and forty-two were free of cardiovascular complications. Control subjects were selected for the absence of personal or familial metabolic or cardiovascular diseases. The frequencies of polymorphic alleles were in agreement with previous studies in the control group: S2 6.3 (95% confidence interval (CI) 2.3-10.3) %, M2 5.5 (1.6-9.4) %, P2 6.3 (2.3-10.3) % and did not differ in the whole diabetic group: S2 4.2 (0.7-7.7) %, M2 6.5 (2.0-11.0) %, P2 6.6 (2.3-10.9) %. The relative prevalences of S2, M2, and P2 alleles were, respectively: 3.32, 1.54, and 2.00 (Woolf's ratio) in the macroangiopathic group but allele distribution frequencies were not statistically different from non-macroangiopathic patients. The allelic associations S2M2P1 and S1M1P2 showed a relative prevalence of 2.86 and 2.00 in the presence of cardiovascular complications but the difference was not significant in terms of polyallelic distribution frequencies in the absence of atherosclerosis. No serum lipid abnormalities could be related to the presence of any polymorphic allele or allelic association. These results suggest a genetic influence on the development of atherosclerosis in Type 2 diabetes, but the mechanism remains unclear.     

Restriction fragment length polymorphism of pepsinogen C gene in patients with gastric carcinoma and in high risk population of gastric carcinoma

AIM: To analyze the difference of distribution of the pepsinogen C (PGC) gene polymorphism among different groups and to study its application value in screening of the high risk population of gastric carcinoma and its value as an indicator for gene diagnosis. METHODS: The study consisted of two parts: study on the restriction fragment length polymorphism (RFLP) of PGC gene in normal individuals and patients with gastric cancer, and study on the PGC gene polymorphism in members from a family at a high risk for stomach carcinoma and the follow-up survey. A total of 40 cases were analyzed including 11 healthy blood donors, 10 gastric carcinoma patients, and 19 members from a high risk family of stomach carcinoma. The Southern blot method was adopted in the study. The probe and restriction endonuclease used were PGC 301 and EcoR I, respectively. Gastroscopy and gastric mucosa biopsy were performed in the follow-up study. RESULTS: There were three kinds of common PGC EcoR I allelic fragments (20 kb, 5.7 kb and 3.6 kb) and only one rare fragment (3.5 kb) in the normal subjects, and there was no difference in allelic fragments between the normal subjects and the patients. The incidence of the rare fragment and rare hybrid band type in the patients was higher than that in the normal subjects. The incidence of rare fragment and rare hybrid band type in the members from a high risk family was a little higher than that in normal subjects. After the 3-year follow-up by gastroscopy, one of the four members from the high risk family with PGC EcoR I rare fragment was found to suffer from early stomach cancer. The hybrid signal of EcoR I common allelic fragments in the gastric tumor tissue was weakened, even disappeared. CONCLUSION: PGC EcoR I rare fragment and rare hybrid band type in the early diagnosis and screening of high-risk population of stomach carcinoma are probably of important application value. There is gastric normal differentiation gene (PGC gene) deletion in the stomach tumor tissue.     

Insulin receptor gene polymorphisms in Type 2 (non-insulin-dependent) diabetes mellitus

Summary The insulin receptor has been proposed as a candidate gene for the inherited defect in Type 2 (non-insulin-dependent) diabetes mellitus and we therefore studied three restriction fragment length polymorphic sites, two revealed with the enzyme Sst1 and one by Rsa1, using two insulin receptor cDNA probes in 131 Caucasian Type 2 diabetic patients and 94 control subjects. The frequency of the six alleles studied did not differ significantly between the two groups. However, one allele, a 6.2 kilobase Rsa1 fragment (R+), was found more frequently in those diabetic subjects (n=48) with a positive family history of diabetes (R+frequency=0.48) compared to those diabetic subjects (n=63) with a negative family history (R+frequency=0.34, p< 0.05). These results suggest that this polymorphism may be a linkage marker for the genetic defect in a subgroup of Type 2 diabetic patients with a positive family history.     

Multiple restriction fragment length polymorphisms at the GLUT2 locus: GLUT2 haplotypes for genetic analysis of Type 2 (non-insulin-dependent) diabetes mellitus

Summary The liver/islet glucose transporter (GLUT2) is expressed in the liver and in the Beta cells of pancreatic islets and is a candidate gene for the inherited defect in Type 2 (non-insulin-dependent) diabetes mellitus. A series of restriction fragment length polymorphisms have been identified using a GLUT2 cDNA probe with five restriction enzymes in a British white Caucasian population. Five independent restriction fragment length polymorphisms detected by restriction enzymes EcoRI (two restriction fragment length polymorphisms termed EcoRI-1, EcoRI-2), TaqI (two restriction fragment length polymorphisms termed TaqI-1, TaqI-2), and BclI (BclI-2) were used to construct GLUT2 haplotypes. Significant linkage disequilibrium was observed between four polymorphic sites EcoRI-2, TaqI-1, TaqI-2 and BclI-2 but linkage disequilibrium was not observed with EcoRI-1 polymorphic site and the other four sites. The frequencies of GLUT2 restriction fragment length polymorphisms and haplotypes in 50 Type 2 diabetic subjects and 50 non-diabetic control subjects show no significant differences suggesting that it is unlikely that there is a single major defect of this gene contributing to the inherited susceptibility to Type 2 diabetes in a Caucasian population.     

我国4种白蛉的核糖体内转录间隔2区PCR-RFLP多态性分析

采用PCR-RFLP方法对我国内脏利什曼病传播媒介中华白蛉(Phlebotomus chinensis)、吴氏白蛉(Ph.wui)、长管白蛉(Ph.longiductus)和亚历山大白蛉(Ph.alexandri)等4种白蛉的核糖体内转录间隔2区(ITS2)进行分型。PCR-RFLP结果显示,以限制性内切酶DraⅠ酶切ITS2片段,可分出4种RFLP带型,即A为450 bp,B为154 bp/127 bp/93 bp/66 bp/10 bp,C为311 bp/80 bp/60 bp,D为353 bp/300 bp/160 bp/58 bp。结果显示,4种白蛉均只有1种RFLP带型,中华白蛉为AA型,亚历山大白蛉为BB型,吴氏白蛉为CC型,长管白蛉为DD型。利用PCR-RFLP方法可区分我国4种内脏利什曼病传播媒介的种类。     

Codon 54 polymorphism of the fatty acid binding protein gene and insulin resistance in the Japanese population.

AIM: To determine the relationship of the polymorphism at codon 54 of the intestinal fatty acid binding protein gene (FABP2) with insulin resistance and susceptibility to Type 2 diabetes mellitus (DM) in the Japanese population. METHODS: We evaluated the polymorphism by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 150 Type 2 DM patients and 147 healthy control subjects. The frequency of alleles encoding threonine (Thr54) and alanine (Ala54) at codon 54 of FABP2 in Type 2 DM patients was compared with that of healthy controls. Insulin sensitivity was assessed by the hyperinsulinaemic euglycaemic clamp in Type 2 DM patients with Ala54 homozygotes, Ala54/Thr54 heterozygotes and Thr54 homozygotes and by homeostasis model assessment (HOMA) in the nondiabetic group. RESULTS: The frequency of alleles encoding Ala54 and Thr54 was 0.59 and 0.41 in Type 2 DM patients, respectively, similar to that observed in nondiabetic controls (0.64 for Ala54 and 0.36 for Thr54). Insulin sensitivity was not significantly different between subjects with and without Thr54 allele either within the DM group or healthy controls. CONCLUSIONS: The allele encoding threonine in the FABP2 does not predispose to Type 2 DM or insulin resistance in the Japanese population.     

乙型肝炎病毒S基因限制性片段长度多态性分型方法的建立及应用

目的 建立乙型肝炎病毒(HBV)S基因片段聚合酶链反应-限制性片段长度多态性(RFLP)的基因分型方法并用于基因型与临床疾病谱关系的研究。 方法 比较GenBank中124株各基因型HBV全序列的S基因核苷酸序列及13株单独S基因序列,设计利用限制性内切酶Mbo Ⅰ、BsTN Ⅰ、BsmA Ⅰ、HpaⅡ酶切S基因片段鉴定HBV基因型(A-F)的方法。对贵州地区176份乙型肝炎患者血清进行基因分型并分析基因型与疾病谱的关系。直接测序2份B型和3份C型毒株的PCR扩增产物,以验证本酶切分型方法的正确性。 结果 测序结果证明本方法能够准确鉴定基因型。在176份标本中,B型100份(56.8％),C型76份(43.2％),未发现其他基因型。B型中无症状携带者(ASC)比例(40.0％)高于C型(15.8％),x2=12.16,P<0.005;慢性中度比例(14.0％)低于C型(31.6％),x2=7.88,P<0,005。 结论 本S基因片段PCR-RFLP基因分型方法简便、准确。贵州地区存在HBV B和C基因型。     

Screening for insulin receptor gene DNA polymorphisms associated with glucose intolerance in a Scandinavian population

Summary The significance of insulin receptor gene variants in the aetiology of Type 2 (non-insulin-dependent) diabetes mellitus has been investigated by analysis of restriction fragment length polymorphisms in a genetically homogeneous Swedish population. Seven polymorphisms were analysed, spanning functionally important regions of the insulin receptor locus. Four of these polymorphisms were mapped more accurately within the gene compared to previous studies. The genotype distribution was compared in 76 Type 2 diabetic patients and 84 healthy control subjects. No significant differences were found in the distribution of genotypes between diabetic and control subjects at the p< 0.01 level. In order to study the possible association between quantitative measures of glucose metabolism and these DNA polymorphisms, the fasting glucose and insulin concentrations were compared in the different genotype groups of control subjects and mildly diabetic patients treated with diet. No differences in fasting glucose or insulin concentrations were found at the p< 0.005 level of significance. In conclusion, no significant associations were found between insulin receptor gene DNA polymorphisms and glucose intolerance.     

Linkage analysis of the human insulin receptor gene in Type 2 (non-insulin-dependent) diabetic families and a family with maturity onset diabetes of the young

Summary The possibility of linkage between the human insulin receptor gene locus and diabetes was examined in three Type 2 (non-insulin-dependent) diabetic families and one family with maturity onset diabetes of the young. Insulin receptor gene haplotypes were established using BglII, Rsal and Sstl restriction enzyme digests of genomic DNA from all available family members. The digested DNA was subjected to agarose gel electrophoresis, Southern blotted, and hybridised to ³²P-labelled human insulin receptor gene cDNA. In the pedigree with maturity onset diabetes of the young, formal linkage analysis allowed exclusion of close linkage between the insulin receptor locus and diabetes (logarithm of the odds for linkage versus non-linkage was –5.35 at recombination fraction of 0.01). This confirms the absence of linkage between insulin receptor and diabetes which has been reported in two similar pedigrees. In the three Type 2 diabetic families there were a minimum of 4 recombinants between the insulin receptor locus and diabetes, which makes a direct role for insulin receptor defects unlikely. The importance of using realistic estimates of penetrance when performing linkage analysis in a disease with a late age of onset is emphasised. In contrast to the one previous linkage analysis study of the insulin receptor gene, no specific association of diabetes with the rare Sstl Sl(-) allele was observed in either the maturity onset diabetes of the young or the Type 2 diabetic families.     

Association between a restriction fragment length polymorphism at the liver/islet cell (GluT 2) glucose transporter and familial Type 2 (non-insulin-dependent) diabetes mellitus

Summary Patients with Type 2 (non-insulin-dependent) diabetes mellitus and a strong family history of the disease may represent a sub-group where genetic factors play a pree-minent role in transmission of the disease. A defect in the liver/islet cell glucose transporter (GluT 2) could explain many of the pathophysiological features of the disease. In order to test the hypothesis that genetic variation at the GluT 2 locus contributes genetic susceptibility to Type 2 diabetes, 60 unrelated Caucasian diabetic patients with at least one affected sibling were genotyped for a Taq 1 restriction fragment length polymorphism marker. Hybridisation with a cDNA GluT 2 probe identified two alleles of sizes 13 kilobase (T1) and 19 kilobase (T2). The allele frequencies in the diabetic group with a family history were significantly different from those in a racially-matched control population of 122 subjects with no personal or family history of the disease (diabetic patients T1=0.96, T2=0.04, control subjects T1=0.89, T2=0.11, p< 0.03). However, when the study was repeated with 54 diabetic patients with indeterminate family history, statistical significance was not reached although the allele frequencies showed a similar trend. The findings of this study support the hypothesis that a genetic variant of the liver/islet cell glucose transporter may contribute to familial susceptibility in Type 2 diabetes.R. D. Lawrence Fellow of the British Diabetic Association     

Detection of carriers of haemophilia A: use of bioassays and restriction fragment length polymorphisms (RFLP)

Abstract Background: Haemophilia A is a sex-linked bleeding disorder carried by unaffected females. Currently, the two main methods used for the determination of carrier status in women from families with haemophilia A are bioassays and DNA-based assays using restriction fragment length polymorphisms (RFLP).
Aim: The aim of this paper was to assess the current usefulness of these two methods.
Methods: Bioassays measured factor VIII coagulation activity by a two-stage coagulation assay and von Willebrand antigen by immunoelectrophoresis. RFLP were determined with two intragenic probes (pi 14 and p486) and two linked probes (Stl4 and DX13). Data were analysed using a Bayesian analysis to allow for all possible recombination events. We also incorporated an estimate for the risk of mosaicism into calculations in isolated haemophilia families. Both bioassays and RFLP were used to determine carrier status in 63 women, 31 from known haemophilia families and 32 from families of isolated cases. The techniques were assessed for their ability to classify the patients as normal (p<0.2) or carrier (p>0.7). Where applicable, intron 22 inversion was also tested.
Results: In the known families, six women could not be classified after bioassay, but all could be classified by RFLP. Of the 32 women from families of isolated cases, eight were unclassified by bioassay and 12 were not definitely classified using RFLP. However, RFLP was useful in determining that a recent mutation had occurred in six of the eight families in which DNA from the grandparents was available.
Conclusion: For diagnosis of carriers of haemophilia, RFLP is the preferred method in familial haemophilia, but is less useful in isolated haemophilia.     

Altered pattern of insulin receptor isotypes in skeletal muscle membranes of Type 2 (non-insulin-dependent) diabetic subjects

Summary The human insulin receptor exists in two isoforms (HIR-A -subunit 719 amino acids and HIR-B -subunit 731 amino acids) which are generated by alternative splicing of a small exon and display distinct patterns of tissue-specific expression. Using the polymerase chain reaction we have recently shown that skeletal muscle of non-diabetic individuals contains predominantly mRNA encoding HIR-A while in skeletal muscle derived from subjects with Type 2 (non-insulin-dependent) diabetes mellitus similar amounts of each mRNA are expressed. We used a polyclonal antibody which discriminates between HIR-A and HIR-B to assess the isoform expression at the protein level. The antibody showed clearly distinct displacement of insulin binding in skeletal muscle membranes of non-diabetic subjects compared to Type 2 diabetic subjects (displacement of specific ¹²⁵I-insulin binding: 13 non-diabetic subjects 70.0%±14.34, 12 Type 2 diabetic subjects 32.6%±17.45). A control antibody which does not discriminate between both isoforms showed similar displacement of ¹²⁵I-insulin in membranes of non-diabetic and Type 2 diabetic subjects. These data suggest that the altered expression of receptor isotype mRNA in the skeletal muscle of Type 2 diabetic subjects leads to an altered receptor isoform pattern in the plasma membrane. While skeletal muscle membranes of non-diabetic subjects contain predominantly HIR-A, membranes of Type 2 diabetic subjects show an increased level of HIR-B in addition to HIR-A.     

Type 2 (non-insulin-dependent) diabetes mellitus associated with a mutation of the glucokinase gene in a Japanese family

Summary Mutations were screened for in the glucokinase gene of 25 Japanese patients with Type 2 (non-insulin-dependent) diabetes mellitus. Each exon was scanned by electrophoresis of enzymatically amplified DNA segments under non-denaturing conditions and variants were sequenced. A variant pattern was detected in exon 5 of one patient. Direct sequencing of this exon revealed a single nucleotide substitution in codon 188 (GCTACT) of one of two alleles resulting in the mutation of Ala¹⁸⁸Thr, an invariant residue in the sequence of all mammalian glucokinases and hexokinases. This mutation was not found in 40 normal control subjects. The proband had been diagnosed with Type 2 diabetes at the age of 62 years. Four other members of her family have the same mutation and all have Type 2 diabetes or impaired glucose tolerance. The youngest age at diagnosis of Type 2 diabetes in these other members was 13 years, suggesting that her pedigree was maturity-onset diabetes of the young (MODY). All subjects with the Thr¹⁸⁸ mutation show a decreased insulin secretory response during oral glucose tolerance testing. Mutations in the glucokinase gene associated with Type 2 diabetes have been previously identified in Caucasian (French and British) subjects. This study indicates that mutations in this gene are also implicated in the development of Type 2 diabetes in Asians. Further studies are required to determine the frequency of mutations in glucokinase among Japanese patients with Type 2 diabetes.