Diabetologia

, Volume 48, Issue 7, pp 1307–1314

Absence of an association between the polymorphisms in the genes encoding adiponectin receptors and type 2 diabetes

  • K. Hara
  • M. Horikoshi
  • H. Kitazato
  • T. Yamauchi
  • C. Ito
  • M. Noda
  • J. Ohashi
  • P. Froguel
  • K. Tokunaga
  • R. Nagai
  • T. Kadowaki
Article

DOI: 10.1007/s00125-005-1806-3

Cite this article as:
Hara, K., Horikoshi, M., Kitazato, H. et al. Diabetologia (2005) 48: 1307. doi:10.1007/s00125-005-1806-3

Abstract

Aims/hypothesis

Secreted by adipocytes, adiponectin is a hormone that acts as an antidiabetic and anti-atherogenic adipokine. We recently cloned the genes encoding two adiponectin receptors (ADIPOR1 and ADIPOR2). The aim of this study was to examine whether ADIPOR1 and/or ADIPOR2 play a major role in genetic susceptibility to insulin resistance or type 2 diabetes in the Japanese population.

Methods

By direct sequencing and a search of public databases, we identified single nucleotide polymorphisms (SNPs) in ADIPOR1 and ADIPOR2, and investigated whether these SNPs are associated with insulin resistance and type 2 diabetes in the Japanese population.

Results

The linkage disequilibrium (LD) in the chromosomal region of ADIPOR1 was almost completely preserved, whereas the LD in ADIPOR2 was less well preserved. None of the SNPs in ADIPOR1 or ADIPOR2 were significantly associated with insulin resistance or type 2 diabetes. No differences in ADIPOR1 or ADIPOR2 haplotype frequencies were observed between type 2 diabetic and non-diabetic subjects.

Conclusions/interpretation

Genetic variations in ADIPOR1 or ADIPOR2 are unlikely to lead to a common genetic predisposition to insulin resistance or type 2 diabetes in the Japanese population.

Keywords

AssociationPolymorphismSusceptibility gene

Abbreviations

LD

linkage disequilibrium

ESM

electronic supplementary material

HOMA

homeostasis model assessment

SNP

single nucleotide polymorphism

Introduction

Adiponectin (also known as the 30-kDa adipocyte complement-related protein, or Acrp30) [14] is a hormone secreted by adipocytes that acts as an antidiabetic adipokine [59]. Levels of adiponectin in the blood are decreased in subjects with obesity, insulin resistance or type 2 diabetes [10, 11]. In animal models, decreased plasma adiponectin is causally involved in insulin resistance and glucose intolerance [69]. In humans, polymorphisms in the gene encoding adiponectin have been shown to be associated with insulin resistance and type 2 diabetes [1214].

We recently cloned cDNAs encoding adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2) [15]. These receptors mediate increases in the AMP kinase [16] and peroxisome proliferator-activated receptor-α ligand activities [17] of adiponectin [15], and are likely to mediate the insulin-sensitising actions of adiponectin. Therefore, ADIPOR1 and ADIPOR2 may be viewed as plausible candidate genes for susceptibility to insulin resistance and type 2 diabetes.

The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in ADIPOR1 and ADIPOR2 influence insulin resistance and susceptibility to type 2 diabetes in the Japanese population.

Subjects and methods

Subjects

The inclusion criteria for the diabetic and non-diabetic subjects enrolled in this study have been described previously [13]. Diabetes was diagnosed according to the criteria of the World Health Organization [18]. All subjects enrolled in this study were of full Japanese ancestry. SNPs in ADIPOR1 and ADIPOR2 were genotyped in 192 diabetic and 192 non-diabetic subjects. The clinical characteristics of the subjects are described in Table 1 of the electronic supplementary material (ESM). Written informed consent was obtained from the subjects, and the study was approved by the Ethics Committee of the University of Tokyo.

Biological measurements

Insulin resistance and beta cell function were assessed using homeostasis model assessment (HOMA). The HOMA of insulin resistance (HOMA-IR) was calculated as fasting insulin (μU/ml)×glucose (mmol/l)/22.5, as described elsewhere [19]. Data are expressed as means±SEM. Since the use of insulin therapy or oral hypoglycaemic agents in subjects with type 2 diabetes is likely to interfere with insulin levels, the correlations between SNPs and insulin resistance were only assessed in non-diabetic subjects.

Screening and selection of SNPs in ADIPOR1 and ADIPOR2

To establish an SNP map encompassing ADIPOR1 and ADIPOR2, SNPs were identified by direct sequencing and a search of public databases. All eight exons in ADIPOR1 and all nine exons in ADIPOR2, plus 50–100 bases of the 5′ and 3′ intronic regions flanking the exons, were amplified and directly sequenced in 30 type 2 diabetic subjects. The conditions and the sequences of the primers used in the PCR are described in Table 2 of the ESM. The SNPs were identified based on the sequences reported in the GenBank database (http://www.ncbi.nih.gov/index.html), which contains ADIPOR1 (accession number NT_004671) and ADIPOR2 (accession number NT_009759). From the public database, 14 SNPs in ADIPOR1 (rs6666089, rs10920534, rs12039275, rs12733285, rs1539355, rs2275738, rs2275737, rs2275735, rs1342387, rs3737884, rs2275736, rs11581, rs1043268, rs1043280) and 29 SNPs in ADIPOR2 (rs2058033, rs6489322, rs12579507, rs11061935, rs7975600, rs10773982, rs11829703, rs12810020, rs11061947, rs11612383, rs11612726, rs9888418, rs7976827, rs12582624, rs10848566, rs7297509, rs12818963, rs10848569, rs11061974, rs2068485, rs7974924, rs12831353, rs12828908, rs10848571, rs7974422, rs2286385, rs730032, rs12342, rs1044471) were selected and validated in 30 type 2 diabetic subjects. From the database, we chose SNPs with a minor allele frequency higher than 10%; we excluded those SNPs for which information on allele frequency was not presented. In total, 25 SNPs in ADIPOR1 and 41 SNPs in ADIPOR2 were identified. Minor allele frequency was determined and Hardy–Weinberg equilibrium was assessed. We eliminated SNPs that deviated from Hardy–Weinberg equilibrium or that had a minor allele frequency lower than 10% from further study. In total, 14 SNPs in ADIPOR1 and 24 SNPs in ADIPOR2 were analysed, resulting in an average SNP density of one SNP per 1.2 kb in ADIPOR1 and one SNP per 3.9 kb in ADIPOR2.

Genotyping of SNPs used in the association study

We genotyped the SNPs in ADIPOR1 and ADIPOR2 in type 2 diabetic subjects and non-diabetic subjects using direct sequencing. PCR was performed under standard conditions. Sequencing reactions were performed using the BigDye terminator kit (Applied Biosystems, Foster City, CA, USA), and the products were resolved using an ABI 3700 automated DNA sequencer (Applied Biosystems). The results were integrated using a Sequencher (Gene Codes Corporation, Ann Arbor, MI, USA), and individual SNPs were manually genotyped. Ambiguous base assignments were eliminated from further analysis.

Statistical analysis

The proportions of genotypes or alleles between subjects with or without type 2 diabetes were compared using a chi square (χ2) test. The differences between subjects with different SNP genotypes were statistically tested using an ANOVA. A Bonferroni adjustment was used to avoid type 1 errors caused by multiple testing. The level of significance for SNPs in ADIPOR1 and ADIPOR2 was 0.001 (0.05 divided by 38, the total number of SNPs for which the association between SNPs and type 2 diabetes was investigated in the present study). We further genotyped SNP15 in ADIPOR2, which showed a tendency towards an association with HOMA (p=0.04), in a second panel to test reproducibility. The statistical analyses, except for those for haplotype estimation, were performed using JUMP for Windows, version 4.00 (SAS Institute, Cary, NC, USA).

Haplotype analysis

Tagged SNPs were selected for haplotype analysis using HaploBlockFinder software (http://www.cgi.uc.edu/cgi-bin/kzhang/haploBlockFinder.cgi, last accessed in April 2005). The tagged SNPs consisted of a minimal set of SNPs that were uniquely distinguishable from at least 90% of the common haplotypes. After selecting the tagged SNPs, the frequency of each haplotype was estimated and differences in haplotype frequencies between non-diabetic and diabetic subjects were assessed using a piece of software based on the Expectation Maximisation algorithm (SNPAlyze; Dynacom, Tokyo, Japan). The differences in the haplotype frequencies were then analysed using the chi square test and the permutation test.

Results

We identified a total of 25 SNPs in ADIPOR1 (Fig. 1a) and 41 SNPs in ADIPOR2 (Fig. 1b). All of the SNPs that were identified had genotype frequencies that were in Hardy–Weinberg equilibrium in non-diabetic and type 2 diabetic subjects (p>0.05). Among these, SNPs with a minor allele frequency higher than 10% were investigated for linkage disequilibrium (LD) in ADIPOR1 and ADIPOR2, and then association with type 2 diabetes and insulin resistance was evaluated. We estimated the degree of LD between pairs of SNPs using an absolute value of D′ (|D′|). For ADIPOR1, the LD extended over 20 kb of the chromosomal region and covered one haplotype block (Fig. 2a). In contrast, the LD in the chromosomal region was less preserved for ADIPOR2 and was split into three haplotype blocks (Fig. 2b). No differences were observed between the diabetic and non-diabetic subjects in terms of the distribution of the genotypes or alleles of the SNPs in ADIPOR1 (Table 1) and ADIPOR2 (Table 2). Only one nominal association was found; this was between SNP15 in ADIPOR2 and HOMA-IR (11/12/22: 1.27±0.05/1.35±0.08/1.81±0.21, p=0.04) (see Tables 3 and 4 of the ESM). When a Bonferroni adjustment was performed (adopted to avoid type 1 errors caused by multiple testing; threshold of significance, p=0.001), no association was found between HOMA-IR and SNP15 in ADIPOR2. Moreover, when SNP15 in ADIPOR2 was further genotyped in 384 additional type 2 diabetic subjects and 384 additional non-diabetic subjects (second panel) to avoid type 2 errors, no significant differences were observed in the HOMA results when compared according to SNP15 genotype (11/12/22: 1.66±0.09/1.62±0.07/1.67±0.13, p=0.91). There were no differences in clinical parameters, such as sex, age, BMI, HbA1c and fasting glucose, between the genotypes of any of the SNPs investigated in the present study (data not shown). We then performed a haplotype analysis, which may be a more sensitive method for detecting associations than the assessment of individual SNPs. First, the haplotype blocks in ADIPOR1 and ADIPOR2 were determined. The tagged SNPs that represented more than 90% of the haplotypes in each block were then selected, and the difference in the frequency of each haplotype between the type 2 diabetic subjects and the non-diabetic subjects was analysed. As shown in Table 3, none of the haplotypes in ADIPOR1 or ADIPOR2 were associated with type 2 diabetes.
Fig. 1

Genomic structure of ADIPOR1 (a) and ADIPOR2 (b) and the locations of the SNPs genotyped in the present study. Exons are shown as boxes, and introns and flanking sequences as lines connecting the boxes. Coding sequences are represented as closed boxes, and untranslated regions as open boxes. The SNPs are numbered in order of appearance from the 5′ to 3′ ends of the genes

Fig. 2

The pairwise marker LD between SNPs in ADIPOR1 (a) and ADIPOR2 (b). The LD between a pair of markers is indicated by the colour of the block (blue to red). Block structure is indicated at the top of each figure as a closed box

Table 1

Comparison of genotypic and allelic distribution of SNPs in ADIPOR1 between type 2 diabetic subjects and non-diabetic subjects

SNP

Rs number

Position (kb)

Genotype, n (%)

p value

Allele, n (%)

p value

SNP1

6666089

−8.505

11

12

22

 

1

2

 

NDM

45 (23.4%)

101 (52.6%)

46 (24.0%)

 

191 (49.7%)

193 (50.3%)

 

T2DM

49 (25.5%)

100 (52.1%)

43 (22.4%)

0.871

198 (51.6%)

186 (48.4%)

0.613

SNP6

12039275

−5.692

11

12

22

 

1

2

 

NDM

78 (40.6%)

90 (46.9%)

24 (12.5%)

 

246 (64.1%)

138 (35.9%)

 

T2DM

79 (41.1%)

87 (45.3%)

26 (13.5%)

0.934

245 (63.8%)

139 (36.2%)

0.94

SNP7

 

−4.612

11

12

22

 

1

2

 

NDM

146 (76.0%)

42 (21.9%)

4 (2.1%)

 

334 (87.0%)

50 (13.0%)

 

T2DM

147 (76.6%)

42 (21.9%)

3 (1.6%)

0.929

336 (87.5%)

48 (12.5%)

0.829

SNP8

 

−4.519

11

12

22

 

1

2

 

NDM

155 (81.2%)

34 (17.8%)

2 (1.0%)

 

344 (90.1%)

38 (9.9%)

 

T2DM

151 (78.6%)

38 (19.8%)

3 (1.6%)

0.790

340 (88.5%)

44 (11.5%)

0.499

SNP9

 

−2.635

11

12

22

 

1

2

 

NDM

165 (85.9%)

27 (14.1%)

0 (0.0%)

 

357 (93.0%)

27 (7.0%)

 

T2DM

157 (81.8%)

34 (17.7%)

1 (0.5%)

0.368

348 (90.6%)

36 (9.4%)

0.237

SNP12

2275738

−0.106

11

12

22

 

1

2

 

NDM

132 (68.8%)

55 (28.6%)

5 (2.6%)

 

319 (83.1%)

65 (16.9%)

 

T2DM

135 (70.3%)

52 (27.1%)

5 (2.6%)

0.943

322 (83.9%)

62 (16.1%)

0.771

SNP13

2275737

−0.102

11

12

22

 

1

2

 

NDM

134 (69.8%)

54 (28.1%)

4 (2.1%)

 

322 (83.9%)

62 (16.1%)

 

T2DM

144 (75.0%)

44 (22.9%)

4 (2.1%)

0.502

332 (86.5%)

52 (13.5%)

0.31

SNP15

 

2.850

11

12

22

 

1

2

 

NDM

126 (65.6%)

60 (31.3%)

6 (3.1%)

 

312 (81.3%)

72 (18.8%)

 

T2DM

138 (71.9%)

50 (26.0%)

4 (2.1%)

0.396

326 (84.9%)

58 (15.1%)

0.178

SNP16

 

3.000

11

12

22

 

1

2

 

NDM

115 (59.9%)

59 (30.7%)

18 (9.4%)

 

289 (75.3%)

95 (24.7%)

 

T2DM

120 (62.5%)

56 (29.2%)

16 (8.3%)

0.860

296 (77.1%)

88 (22.9%)

0.553

SNP18

1342387

5.841

11

12

22

 

1

2

 

NDM

45 (23.4%)

103 (53.6%)

44 (22.9%)

 

193 (50.3%)

191 (49.7%)

 

T2DM

53 (27.6%)

97 (50.5%)

42 (21.9%)

0.644

203 (52.9%)

181 (47.1%)

0.47

SNP19

3737884

6.993

11

12

22

 

1

2

 

NDM

151 (79.1%)

38 (19.9%)

2 (1.0%)

 

340 (89.0%)

42 (11.0%)

 

T2DM

151 (78.6%)

39 (20.3%)

2 (1.0%)

0.995

341 (88.8%)

43 (11.2%)

0.929

SNP20

 

7.477

11

12

22

 

1

2

 

NDM

75 (39.1%)

93 (48.4%)

24 (12.5%)

 

243 (63.3%)

141 (36.7%)

 

T2DM

67 (34.9%)

98 (51.0%)

27 (14.1%)

0.685

232 (60.4%)

152 (39.6%)

0.414

SNP22

2275736

8.712

11

12

22

 

1

2

 

NDM

136 (70.8%)

53 (27.6%)

3 (1.6%)

 

325 (84.6%)

59 (15.4%)

 

T2DM

139 (72.4%)

49 (25.5%)

4 (2.1%)

0.847

327 (85.2%)

57 (14.8%)

0.840

SNP23

10581

9.879

11

12

22

 

1

2

 

NDM

150 (78.1%)

39 (20.3%)

3 (1.6%)

 

339 (88.3%)

45 (11.7%)

 

T2DM

140 (72.9%)

49 (25.5%)

3 (1.6%)

0.477

329 (85.7%)

55 (14.3%)

0.284

NDM Non-diabetic subjects; T2DM type 2 diabetic subjects; 11 major/major; 12 major/minor; 22 minor/minor

Table 2

Comparison of the genotypic and allelic distribution of SNPs in ADIPOR2 between type 2 diabetic subjects and non-diabetic subjects

SNP

Rs number

Position, kb

Genotype, n (%)

p value

Allele, n (%)

p value

SNP2

2058033

−77.219

11

12

22

 

1

2

 

NDM

99 (51.6%)

78 (40.6%)

15 (7.8%)

 

276 (71.9%)

108 (28.1%)

 

T2DM

91 (47.4%)

84 (43.8%)

17 (8.9%)

0.710

266 (69.3%)

118 (30.7%)

0428

SNP4

12579507

−71.725

11

12

22

 

1

2

 

NDM

84 (43.8%)

88 (45.8%)

20 (10.4%)

 

256 (66.7%)

128 (33.3%)

 

T2DM

79 (41.1%)

89 (46.4%)

24 (12.5%)

0.770

247 (64.3%)

137 (35.7%)

0.495

SNP8

 

−60.706

11

12

22

 

1

2

 

NDM

93 (48.4%)

82 (42.7%)

17 (8.9%)

 

268 (69.8%)

116 (30.2%)

 

T2DM

89 (46.4%)

84 (43.8%)

19 (9.9%)

0.894

262 (68.2%)

122 (31.8%)

0.640

SNP10

10773982

−53.950

11

12

22

 

1

2

 

NDM

52 (27.1%)

98 (51.0%)

42 (21.9%)

 

202 (52.6%)

182 (47.4%)

 

T2DM

62 (32.3%)

96 (50.0%)

34 (17.7%)

0.419

220 (57.3%)

164 (42.7%)

0.192

SNP12

12810020

−52.196

11

12

22

 

1

2

 

NDM

77 (40.1%)

92 (47.9%)

23 (12.0%)

 

246 (64.1%)

138 (35.9%)

 

T2DM

85 (44.3%)

84 (43.8%)

23 (12.0%)

0.684

254 (66.1%)

130 (33.9%)

0.545

SNP13

11061947

−50.799

11

12

22

 

1

2

 

NDM

123 (64.1%)

62 (32.3%)

7 (3.6%)

 

308 (80.2%)

76 (19.8%)

 

T2DM

120 (62.5%)

63 (32.8%)

9 (4.7%)

0.863

303 (78.9%)

81 (21.1%)

0.655

SNP14

11612383

−50.744

11

12

22

 

1

2

 

NDM

56 (29.2%)

96 (50.0%)

40 (20.8%)

 

208 (54.2%)

176 (45.8%)

 

T2DM

51 (26.6%)

101 (52.6%)

40 (20.8%)

0.835

203 (52.9%)

181 (47.1%)

0.718

SNP15

11612726

−47.171

11

12

22

 

1

2

 

NDM

129 (67.2%)

57 (29.7%)

6 (3.1%)

 

315 (82.0%)

69 (18.0%)

 

T2DM

121 (63.0%)

64 (33.3%)

7 (3.6%)

0.691

306 (79.7%)

78 (20.3%)

0.409

SNP17

7976827

−40.160

11

12

22

 

1

2

 

NDM

69 (36.1%)

103 (53.9%)

19 (9.9%)

 

241 (63.1%)

141 (36.9%)

 

T2DM

64 (33.3%)

97 (50.5%)

31 (16.1%)

0.197

225 (58.6%)

159 (41.4%)

0.203

SNP18

12582624

−39.956

11

12

22

 

1

2

 

NDM

71 (37.0%)

94 (49.0%)

27 (14.1%)

 

236 (61.5%)

148 (38.5%)

 

T2DM

78 (40.6%)

90 (46.9%)

24 (12.5%)

0.744

246 (64.1%)

138 (35.9%)

0.455

SNP20

 

−39.862

11

12

22

 

1

2

 

NDM

63 (32.8%)

99 (51.6%)

30 (15.6%)

 

225 (58.6%)

159 (41.4%)

 

T2DM

57 (29.7%)

99 (51.6%)

36 (18.8%)

0.655

213 (55.5%)

171 (44.5%)

0.382

SNP21

7297509

−33.122

11

12

22

 

1

2

 

NDM

75 (39.1%)

92 (47.9%)

25 (13.0%)

 

242 (63.0%)

142 (37.0%)

 

T2DM

89 (46.4%)

81 (42.2%)

22 (11.5%)

0.352

259 (67.4%)

125 (32.6%)

0.198

SNP22

12818963

−30.884

11

12

22

 

1

2

 

NDM

67 (34.9%)

96 (50.0%)

29 (15.1%)

 

230 (59.9%)

154 (40.1%)

 

T2DM

79 (41.1%)

87 (45.3%)

26 (13.5%)

0.451

245 (63.8%)

139 (36.2%)

0.265

SNP23

 

−29.409

11

12

22

 

1

2

 

NDM

74 (38.5%)

92 (47.9%)

26 (13.5%)

 

240 (62.5%)

144 (37.5%)

 

T2DM

81 (42.2%)

90 (46.9%)

21 (10.9%)

0.647

252 (65.6%)

132 (34.4%)

0.367

SNP25

10848569

−21.557

11

12

22

 

1

2

 

NDM

48 (25.0%)

101 (52.6%)

43 (22.4%)

 

197 (51.3%)

187 (48.7%)

 

T2DM

52 (27.1%)

95 (49.5%)

45 (23.4%)

0.823

199 (51.8%)

185 (48.2%)

0.885

SNP26

11061974

−15.081

11

12

22

 

1

2

 

NDM

45 (23.4%)

99 (51.6%)

48 (25.0%)

 

189 (49.2%)

195 (50.8%)

 

T2DM

47 (24.5%)

98 (51.0%)

47 (24.5%)

0.971

192 (50.0%)

192 (50.0%)

0.829

SNP27

2068485

−13.571

11

12

22

 

1

2

 

NDM

63 (32.8%)

95 (49.5%)

34 (17.7%)

 

221 (57.6%)

163 (42.4%)

 

T2DM

60 (31.3%)

97 (50.5%)

35 (18.2%)

0.947

21 (56.5%)

167 (43.5%)

0.771

SNP28

7974924

−9.821

11

12

22

 

1

2

 

NDM

56 (29.2%)

96 (50.0%)

40 (20.8%)

 

208 (54.2%)

176 (45.8%)

 

T2DM

51 (26.6%)

96 (50.0%)

45 (23.4%)

0.768

198 (51.6%)

186 (48.4%)

0.470

SNP29

12831353

−6.333

11

12

22

 

1

2

 

NDM

95 (49.5%)

74 (38.5%)

23 (12.0%)

 

264 (68.8%)

120 (31.3%)

 

T2DM

78 (40.6%)

89 (46.4%)

25 (13.0%)

0.208

245 (63.8%)

139 (36.2%)

0.147

SNP30

12828908

−2.713

11

12

22

 

1

2

 

NDM

50 (26.0%)

94 (49.0%)

48 (25.0%)

 

194 (50.5%)

190 (49.5%)

 

T2DM

36 (18.8%)

96 (50.0%)

60 (31.3%)

0.163

168 (43.8%)

216 (56.3%)

0.060

SNP31

10848571

0.374

11

12

22

 

1

2

 

NDM

104 (54.2%)

76 (39.6%)

12 (6.3%)

 

284 (74.0%)

100 (26.0%)

 

T2DM

91 (47.4%)

83 (43.2%)

18 (9.4%)

0.305

265 (69.0%)

119 (31.0%)

0.129

SNP36

2286385

8.490

11

12

22

 

1

2

 

NDM

56 (29.2%)

98 (51.0%)

38 (19.8%)

 

210 (54.7%)

174 (45.3%)

 

T2DM

48 (25.0%)

100 (52.1%)

44 (22.9%)

0.584

196 (51.0%)

188 (49.0%)

0.312

SNP39

 

13.274

11

12

22

 

1

2

 

NDM

52 (27.1%)

98 (51.0%)

42 (21.9%)

 

202 (52.6%)

182 (47.4%)

 

T2DM

61 (31.8%)

96 (50.0%)

35 (18.2%)

0.503

218 (56.8%)

166 (43.2%)

0.246

SNP40

12342

14.800

11

12

22

 

1

2

 

NDM

55 (28.6%)

97 (50.5%)

40 (20.8%)

 

207 (53.9%)

177 (46.1%)

 

T2DM

46 (24.0%)

99 (51.6%)

47 (24.5%)

0.500

191 (49.7%)

193 (50.3%)

0.248

SNP41

1044471

14.858

11

12

22

 

1

2

 

NDM

78 (40.6%)

90 (46.9%)

24 (12.5%)

 

246 (64.1%)

138 (35.9%)

 

T2DM

70 (36.5%)

94 (49.0%)

28 (14.6%)

0.661

234 (60.9%)

150 (39.1%)

0.371

NDM Non-diabetic subjects; T2DM type 2 diabetic subjects; 11 major/major; 12 major/minor; 22 minor/minor

Table 3

Distribution of the haplotypes composed of the tagged SNPs in ADIPOPR1 and ADIPOR2 in type 2 diabetic subjects and non-diabetic subjects

Haplotype

T2DM

NDM

p value

Permutation p value

ADIPOR1

 00000

0.4790

0.4521

0.4549

0.3863

 10010

0.0500

0.0509

0.9545

0.2367

 10001

0.0782

0.0876

0.6367

0.3687

 11001

0.1858

0.1934

0.7882

0.6101

 11011

0.0600

0.0746

0.4194

0.2117

 11111

0.1093

0.0892

0.3521

0.2400

ADIPOR2

 00000

0.5289

0.5260

0.9358

0.6748

 11010

0.0653

0.0436

0.1852

0.1443

 11011

0.1530

0.1878

0.1992

0.1974

 11111

0.1694

0.1626

0.8010

0.6435

ADIPOR2

 00

0.6235

0.6809

0.0949

0.1020

 10

0.0521

0.0567

0.7787

0.6882

 11

0.3075

0.2582

0.1290

0.0720

ADIPOR2

 00

0.5079

0.5470

0.2782

0.0926

 10

0.1011

0.0761

0.2226

0.0585

 11

0.3836

0.3614

0.5249

0.1326

The ‘0’ and ‘1’ used for haplotype notation stand for ‘major allele’ and ‘minor allele’, respectively

NDM Non-diabetic subjects; T2DM type 2 diabetic subjects

Discussion

After constructing a dense map of SNPs in ADIPOR1 and ADIPOR2 and performing haplotype analysis, no evidence of a major role for ADIPOR1 or ADIPOR2 in susceptibility to type 2 diabetes or insulin resistance was found in a Japanese population. Our results may reflect a type 2 error (false-negative result), but this is unlikely. First, SNP densities of one SNP every 1.2 kb in ADIPOR1 and one SNP every 3.9 kb in ADIPOR2 were used for the association study. The distance between each SNP was short, and the LD between them was fully analysed. We estimated that more than 90% of the haplotypes in ADIPOR1 and ADIPOR2 were covered. Second, the sample size used in the present study had an 80% power to detect the effect of a polymorphism, conferring an odds ratio of 2.0 at a significance level of 5% (assuming an allele frequency of 40% in the control population). However, it cannot be excluded that SNPs in ADIPOR1 and/or ADIPOR2 had a minor effect on susceptibility to type 2 diabetes.

Consistent with our results for ADPOR1, an American study recently reported that SNPs in ADIPOR1 were not associated with type 2 diabetes in Caucasians or African Americans [20]. However, they reported that the level of expression of ADIPOR1 in lymphocytes from type 2 diabetic subjects was reduced compared with that in lymphocytes from non-diabetic subjects, implicating ADIPOR1 in the pathogenesis of type 2 diabetes. Further analysis is needed to clarify the role played by ADIPOR2 in susceptibility to type 2 diabetes in different ethnic groups.

In summary, the genetic variations in ADIPOR1 or ADIPOR2 investigated in the present study were not associated with insulin resistance or type 2 diabetes. However, further studies using denser SNPs and larger samples may be required to conclusively determine that genetic variations in ADIPOR1 or ADIPOR2 are not major genetic determinants of the development of type 2 diabetes or insulin resistance.

Acknowledgements

K. Hara and M. Horikoshi contributed equally to this study. This work was supported by a grant-in-aid (to T. Kadowaki) from the Organization for Pharmaceutical Safety and Research (Tokyo, Japan), and a grant-in-aid (to R. Nagai) for The 21st Century Center of Excellence Program from the Ministry of Education, Culture, Science, Sports and Technology of Japan. We thank Y. Okada for technical assistance.

Supplementary material

125_2005_1806_ESM_supp.pdf (158 kb)
(PDF 158 KB)

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • K. Hara
    • 1
    • 2
    • 3
  • M. Horikoshi
    • 1
  • H. Kitazato
    • 4
  • T. Yamauchi
    • 1
  • C. Ito
    • 5
  • M. Noda
    • 6
  • J. Ohashi
    • 7
  • P. Froguel
    • 8
    • 9
  • K. Tokunaga
    • 7
  • R. Nagai
    • 2
  • T. Kadowaki
    • 1
    • 3
  1. 1.Department of Metabolic Diseases, Graduate School of MedicineUniversity of TokyoTokyoJapan
  2. 2.Department of Clinical Bioinformatics, Graduate School of MedicineUniversity of TokyoTokyoJapan
  3. 3.Core Research for Evolution Science and Technology (CREST), Japan Science and Technology Corporation (JST)TokyoJapan
  4. 4.Institute for Diabetes Care and ResearchAsahi Life FoundationTokyoJapan
  5. 5.Hiroshima Atomic Bomb Casualty Council Health Management CenterHiroshimaJapan
  6. 6.Department of Endocrinology and MetabolismToranomon HospitalTokyoJapan
  7. 7.Department of Human Genetics, Graduate School of MedicineUniversity of TokyoTokyoJapan
  8. 8.Institute of Biology—CNRS 8090Pasteur Institute of LilleLilleFrance
  9. 9.Imperial College Genome Centre and Genomic MedicineLondonUK