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The Journal of Clinical Endocrinology & Metabolism Vol. 85, No. 5 2014-2019
Copyright © 2000 by The Endocrine Society


Original Studies

Peroxisome Proliferator-Activated Receptor-{gamma}2 P12A and Type 2 Diabetes in Canadian Oji-Cree1

Robert A. Hegele2, Henian Cao, Stewart B. Harris3, Bernard Zinman, Anthony J. G. Hanley4 and Carol M. Anderson

John P. Robarts Research Institute (R.A.H., H.C., C.M.A.) and Centre for Studies in Family Medicine (S.B.H.), University of Western Ontario, London, Ontario, Canada N6A 5K8; and Samuel Lunenfeld Research Institute and Department of Medicine (B.Z., A.J.G.H.), Mount Sinai Hospital, University of Toronto, Ontario, Canada M5G 1X5

Address correspondence and requests for reprints to: Robert A. Hegele, Blackburn Cardiovascular Genetics Laboratory, Robarts Research Institute, 406-100 Perth Drive, London, Ontario, Canada N6A 5K8. E-mail: robert.hegele{at}rri.on.ca


    Abstract
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
Among the Oji-Cree of northern Ontario, we previously identified a novel variant in the HNF1A gene, namely G319S, that was strongly associated with type 2 diabetes. However, the majority of subjects with diabetes did not have the HNF1A S319 variant, suggesting that there might be other genetic determinants of diabetes susceptibility. In the course of sequencing candidate genes in diabetic subjects who were homozygous for HNF1A G319/G319, we found that some of them had the PPARG A12 variant. After genotyping PPARG in the entire adult Oji-Cree population, we found that: 1) PPARG A12 was strongly associated with type 2 diabetes in women, but not men; 2) among women, the odds of being affected for carriers of PPARG A12 compared with noncarriers was 2.3 (95% confidence interval, 1.4–3.8); and 3) among women, affected carriers of PPARG A12 had a significantly earlier age-of-onset and/or age-at-diagnosis compared with noncarriers. When taken together with the previously reported association of diabetes with HNF1A in both men and women, the gender-specific association with PPARG A12 confirms that type 2 diabetes is etiologically complex in the Oji-Cree and that at least two genes are involved in determining susceptibility to the disease in these people.


    Introduction
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
WE PREVIOUSLY found a strong association between type 2 diabetes in the Oji-Cree of northern Ontario and the G319S variant in the HNF1A gene, which encodes hepatocyte nuclear factor-1{alpha} (HNF-1{alpha}) (1, 2). Individuals with one and two copies of the HNF1A S319 allele had, respectively, a 2- and 4-fold increased relative risk of having type 2 diabetes (1, 2). Among subjects whose age-of-onset of diabetes was under 35, almost 50% had at least one copy of the HNF1A S319 allele. The observation that a population-specific genetic variant was present in such a high proportion of affected subjects is unique in the area of the genetics of diabetes and in the field of complex diseases, in general. However, more than half of Oji-Cree with early-onset type 2 diabetes did not carry the HNF1A S319 allele. We have strongly suspected that variants in other genes determined diabetes susceptibility among the Oji-Cree with "non-HNF1A S319-associated" type 2 diabetes; in other words, among affected individuals who were HNF1A G319/G319 homozygotes.

PPARG, on chromosome 3p25, encodes the nuclear receptor peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) (3, 4, 5). PPARG is an attractive candidate gene for susceptibility to type 2 diabetes and related phenotypes because its products play a key role in the modulation of insulin sensitivity, inflammation, and in adipocyte differentiation and proliferation, through regulation of the expression of adipocyte-specific developmental genes (3, 4, 5). Two isoforms, called PPAR{gamma}1 and -{gamma}2, are produced from alternative splicing of the PPARG messenger RNA (3, 4, 5). Pharmacologic activation of PPAR{gamma} by thiazolidinediones is associated with improvement of insulin sensitivity, probably through enhancement of insulin-stimulated tyrosine phosphorylation of genes involved in insulin signaling pathways (3, 4, 5).

There is a relatively common PPARG nucleotide sequence change that encodes a variant form of PPAR{gamma}2, designated P12A (6, 7, 8, 9, 10). This nonconservative change is very close to the amino terminus of the mature protein, and the resulting change in the primary structure of the ligand-independent activation domain would be expected to reduce the stability of a putative {alpha}-helix (6, 7, 8, 9, 10). PPARG A12 had decreased binding affinity to the cognate PPAR promoter element and, thus, lower in vitro transactivation capacity (9). However, PPARG P12, which had greater in vitro activity than A12, was found to be associated with metabolically deleterious phenotypes, such as decreased insulin sensitivity, obesity, and type 2 diabetes in samples taken from Japanese and Finnish populations (9). This somewhat counterintuitive observation was reconciled by the investigators’ suggestion that PPARG A12 produced lower accumulation of adipose tissue due to less efficient stimulation of PPAR{gamma} target genes (9). In two other studies of Caucasians, there was no association of PPARG P12A with diabetes (8, 10), but one study did report an association of A12 with increased body mass index (BMI) (8).

We have used a strategy composed of both association and linkage analysis to identify susceptibility genes for type 2 diabetes in Oji-Cree (1, 2, 11). One component of this strategy has been to sequence the coding and 5'- and 3'-untranslated flanking regions of candidate genes in Oji-Cree subjects with and without type 2 diabetes. We now report that PPARG A12 was associated with type 2 diabetes and with an earlier age-of-onset among subjects, particularly women, who were HNF1A G319 homozygotes. PPARG A12 is the second variant associated with diabetes in the Oji-Cree, confirming the earlier impression of genetic heterogeneity in this sample.


    Subjects and Methods
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
Study subjects

The community of Sandy Lake, Ontario, is located about 2000 km northwest of Toronto, in the subarctic boreal forest of central Canada. Seven hundred twenty-eight members (72% of the total population) of this community aged 10 yr and above participated in the Sandy Lake Health and Diabetes Project (1, 2, 11, 12, 13, 14, 15, 16, 17, 18, 19). Several complete clinical descriptions of the entire study sample have already been published (1, 2, 11, 12, 13, 14, 15, 16, 17, 18, 19). The project was approved by The University of Toronto Ethics Review Committee and the Sandy Lake First Nations Band Council.

Biochemical analyses

Plasma samples were obtained with informed consent. Exclusion criteria were an inadequate blood sample available for all biochemical and/or genetic determinations. Subjects gave plasma samples after fasting overnight for 12 h. Blood was centrifuged at 2000 rpm for 30 min, and the plasma was stored at -70 C. Concentrations of fasting plasma glucose and insulin were determined, as described (12). A standard 75-g oral glucose tolerance test (OGTT) was then administered, and a second blood sample was collected after 2 h for plasma glucose determination. Subjects were excluded from the OGTT if they had physician-diagnosed diabetes and/or if they were currently receiving treatment with insulin and/or oral hypoglycemic agents or if they had a fasting blood glucose exceeding 11.1 mmol/L. Subjects who were pregnant at the time of recruitment had their OGTT deferred until three months postpartum. Type 2 diabetes, impaired glucose tolerance (IGT), and normal glucose tolerance (nondiabetic) were diagnosed using pre-1997 criteria (20, 21).

Genetic analyses

We had previously determined genotypes for HNF1A G319S (1, 2). We then screened for candidate gene mutations in subjects without HNF1A S319. The genes that we have sequenced, to date, have included IPF-4, GK, HNF-4, and IAPP. We sequenced the exons and the 5'- and 3'-untranslated regions from the entire PPARG gene in three unrelated subjects with type 2 diabetes, whose age-of-onset was 35 yr or under and whose HNF1A genotype was G319/G319. We also performed sequencing in three unrelated nondiabetic subjects, whose age was 60 yr or older, whose BMI was 30 kg/m2 or greater, and whose HNF1A genotype was G319/G319. We used published sequence information to derive amplification primers for all coding sequences and the 5'- and 3'-untranslated regions from PPARG (22). Amplified products were directly sequenced in both directions with an ABI 377 automated DNA sequencer (PE Applied Biosystems Inc., Mississauga, Ontario, Canada). ABI Sequence Navigator software (PE Applied Biosystems Inc.) was used to align and compare amplified DNA fragments for sequence differences. The only PPARG sequence variant that was found was PPARG P12A. The PPARG A12 allele was observed in two of these subjects with diabetes and in none of the three control subjects. This variant could be detected by amplification of exon 6, followed by restriction digestion with HgaI, as described (7).

Statistical analyses

SAS (Version 6.12) was used for all statistical comparisons (23). Between-group differences in proportions of alleles or genotypes were compared using {chi}2 analysis and a two-tailed Fisher’s exact test. Estimates of relative risk of type 2 diabetes between genotypes were determined using odds ratios from the Mantel-Haenszel method. The LIFETEST log rank procedure was used to determine differences between the genotypes with respect to age-of-onset or age-at-diagnosis for affected subjects.

For continuous traits, ANOVAs were performed using the general linear models procedure separately in affected and unaffected men and women. All continuous traits had distributions that differed significantly from the normal distribution according to Wilk’s test of normality. After transformation using the natural logarithm (log), each trait had a distribution that was no longer significantly different from normal. ANOVA was used to determine the sources of variation for log fasting plasma glucose, log fasting insulin and C-peptide, and log plasma glucose post challenge. F tests were computed from the type III sums of squares (23). This form of sums of squares is applicable to unbalanced study designs and adjusts the level of significance to account for other independent variables included in the model. Independent variables for each ANOVA were sex, age, BMI, and genotypes.


    Results
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
Baseline clinical and biochemical features

Baseline attributes for the entire study sample are shown in Table 1Go. For the purpose of genetic analysis, affected subjects were considered to have either definite diabetes or IGT. In this data set, 47 men had definite type 2 diabetes, 13 men had IGT, 68 women had definite type 2 diabetes, and 51 women had IGT. As we previously reported (12), there was a significant difference in the proportion of affected women and men (42.9% vs. 27.2%, P < 0.0001). Therefore, for all subsequent analyses, men and women were studied separately.


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Table 1. Baseline clinical and biochemical attributes of adult Oji-Cree study subjects

 
Allele and genotype frequencies

The tables generally report proportions of subjects or means ± SD for the entire study sample and also for the subgroup of subjects who were homozygous for HNF1A G319/G319. However, a priori comparisons of allele frequencies and odds ratios related to PPARG genotypes were performed only for the subgroup of subjects who were homozygous for HNF1A G319/G319.

The HNF1A allele and genotype frequencies are shown in Table 2Go. The genotype frequencies for each group were within Hardy-Weinberg expectations. Consistent with our previous observations, the overall frequencies of the HNF1A S319 allele in the affected and unaffected groups were significantly different (0.173 and 0.087, respectively; P = 0.00012). In Oji-Cree men, the frequencies of the HNF1A S319 allele in the affected and unaffected groups were significantly different (0.250 and 0.109, respectively; P = 0.00057). In Oji-Cree women, the frequencies of the HNF1A S319 allele in the affected and unaffected groups were significantly different (0.135 and 0.067, respectively; P = 0.011).


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Table 2. HNF1A allele and genotype frequencies in adult Oji-Cree study subjects

 
The PPARG allele and genotype frequencies are shown in Table 3Go. The genotype frequencies for each group were within Hardy-Weinberg expectations. Because we were interested only in the association of the PPARG alleles with diabetes in subjects who did not have HNF1A-associated diabetes, we did not perform an a priori analysis on the entire study sample. However, a post hoc analysis showed that the overall frequencies of the PPARG A12 allele in the affected and unaffected groups were not significantly different (0.106 and 0.084, respectively; P = 0.49). In Oji-Cree men, the frequencies of the PPARG A12 allele in the affected and unaffected groups were not significantly different (0.075 and 0.099, respectively; P = 0.10). However, in Oji-Cree women, the frequencies of the PPARG A12 allele in the affected and unaffected groups were significantly different (0.122 and 0.070, respectively; P = 0.018).


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Table 3. PPARG allele and genotype frequencies in adult Oji-Cree study subjects

 
The PPARG allele and genotype frequencies in subjects who were homozygous for HNF1A G319/G319 are shown in Table 4Go. The genotype frequencies for each group were within Hardy-Weinberg expectations. In Oji-Cree men, the frequencies of the PPARG A12 allele in the affected and unaffected groups were not significantly different (0.106 and 0.106, respectively; P = 0.99). However, in Oji-Cree women, the frequencies of the PPARG A12 allele in the affected and unaffected groups were significantly different (0.146 and 0.068, respectively; P = 0.0017).


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Table 4. PPARG allele and genotype frequencies in adult Oji-Cree homozygotes for HNF1A G319/G319

 
Among all subjects who were homozygous for HNF1A G319/G319, the odds ratio for being affected for carriers of PPARG A12 was 1.6 [95% confidence interval (CI), 1.1–2.4). For male HNF1A G319/G319 homozygotes, this odds ratio was 0.9 (95% CI, 0.4–1.9). For female HNF1A G319/G319 homozygotes, this odds ratio was 2.3 (95% CI, 1.4–3.8).

Among all subjects who were homozygous for PPARG P12/P12, the odd ratios for being affected for carriers of HNF1A S319 was 1.9 (95% CI, 1.4–2.6). For male PPARG P12/P12 homozygotes, this odds ratio was 2.1(95% CI, 1.4–3.2). For female PPARG P12/P12 homozygotes, this odds ratio was 2.3 (95% CI, 1.4–4.0).

Finally, among subjects under age 45, 57.4% of affected subjects had at least one of PPARG A12 or HNF1A S319, compared with 32.2% of unaffected subjects (P = 0.0000006). Among men under age 45, 64.9% of affected subjects had at least one of PPARG A12 or HNF1A S319, compared with 37.2% of unaffected subjects (P = 0.003). Among women under age 45, 54.1% of affected subjects had at least one of PPARG P12 or HNF1A S319, compared with 28.2% of unaffected subjects (P = 0.00002).

Age-of-onset or -diagnosis in affected subjects according to PPARG genotype

Fig. 1Go shows a plot of the cumulative proportion of affected women who were homozygous for HNF1A G319/G319 with age-of-onset or -diagnosis on the abscissa, according to PPARG genotype. The curves for the PPARG P12/P12 homozygotes and A12/P12 heterozygotes were significantly different (P < 0.05). The curves for the affected men were not significantly different (data not shown, P = 0.16).



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Figure 1. Cumulative percentage of affected Oji-Cree women who were homozygous for HNF1A G319/G319 by age-of-onset or -diagnosis, according to PPARG genotype. The curves for the PPARG P12/P12 homozygotes and PPARG A12 carriers were significantly different (P < 0.05).

 
Clinical and biochemical traits in subjects according to PPARG genotype

Affected and unaffected men and women were evaluated separately for differences between genotypes in clinical and biochemical traits. Because the association with PPARG was seen only in females, the means SD) for both the female overall sample and subgroups of HNF1A G319/G319 homozygotes are shown in Tables 5Go and 6Go. None of the between-genotype differences was statistically significant.


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Table 5. Baseline clinical and biochemical attributes of affected female Oji-Cree according to PPARG genotype

 

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Table 6. Baseline clinical and biochemical attributes of unaffected female Oji-Cree according to PPARG genotype

 
The clinical and biochemical attributes of the two affected men with both HNF1A S319 and PPARG A12 were compared with the other affected men. No significant differences were observed (data not shown). The clinical and biochemical attributes of the three affected women with both HNF1A S319 and PPARG A12 were compared with the other affected women. No significant differences were observed (data not shown). There were also no significant differences in clinical and biochemical traits between unaffected carriers of both mutations and unaffected subjects who carried neither (data not shown). The failure to detect significant differences may be due to small numbers.


    Discussion
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
In this sample of Oji-Cree, we have found that PPARG A12 was strongly associated with type 2 diabetes in Oji-Cree women, but not men. The odds of being affected in female carriers of PPARG A12 compared with noncarriers was 2.3 (95% CI, 1.4–3.8). Furthermore, affected female carriers of PPARG A12 had a significantly earlier age-of-onset and/or age-at-diagnosis compared with noncarriers. When taken together with the previously reported association of diabetes with HNF1A in both men and women, the gender-specific association with PPARG A12 confirms that type 2 diabetes is etiologically complex in the Oji-Cree and that at least two genes are involved in determining susceptibility to the disease.

We recognized previously that, despite the extremely strong evidence for its role in type 2 diabetes susceptibility in the Oji-Cree, HNF1A S319 could not fully explain the genetic component of susceptibility to diabetes. The association with PPARG A12 was identified by analyzing the subgroup of subjects who were homozygous for HNF1A G319/G319. By definition, HNF1A G319/G319 homozygotes could not develop HNF1A S319-associated type 2 diabetes and must have had a different genetic basis for their diabetes. Because these homozygotes constituted about 70% of the affected subjects, we reasoned that this subgroup would be large enough to detect associations with other genetic variants. The association with PPARG A12 could be detected in the overall HNF1A G319/G319 homozygote subgroup, but this was due mainly to the increased frequency of the marker in affected Oji-Cree women, not in affected men.

The association of PPARG A12 with type 2 diabetes seems to be at variance with the previous observation of an increased odds of diabetes in Japanese American homozygotes for P12 (9). These investigators also found that A12 was associated with lower BMI and improved insulin sensitivity among middle-aged and elderly Finns (9). These previously reported findings were somewhat counterintuitive because the A12 allele showed decreased binding affinity to the cognate promoter element and reduced ability to transactivate responsive promoters (9). Our finding of an association between PPARG A12 and more deleterious phenotypes would be more consistent with the demonstrated loss of function of the PPAR{gamma} A12 variant at the cellular level.

The disparities between association studies may be related to differences in ethnic background, study design, phenotype studied, and secondary factors, such as the effects of age, BMI, and gender. As always in association studies, there is the possibility that the marker under study, while having a proven in vitro functional consequence, may simply be in linkage disequilibrium with the true causative genomic variant within or proximal to the study locus. There may be differences in linkage disequilibrium relationships between study samples, which could also explain the differences in the observed associations.

Although PPAR{gamma} seems to be important in modulating insulin sensitivity, our results indicate that there are no between-PPARG genotype differences in fasting plasma insulin or C-peptide concentrations, for either men or women, with or without diabetes. This implies that the plasma insulin in subjects with PPARG A12 is insufficient to prevent the development of diabetes. Whether this is related to increased peripheral insulin resistance among carriers of PPARG A12 remains to be determined by cellular and/or in vivo physiological studies.

The findings also indicate that the association of PPARG A12 with type 2 diabetes in the Oji-Cree differs between men and women. One factor underlying this apparent gender difference could be the relatively lower burden of obesity among Oji-Cree men compared with women (12). Because obesity contributes to insulin resistance, it is possible that the general tendency for earlier-onset obesity among Oji-Cree women would result in more insulin resistance at younger ages in women compared with men. However, there were no between-genotype differences in BMI, suggesting that variation in PPAR{gamma} activity was not a primary determinant of obesity. Another factor could be the higher serum concentration of leptin in Oji-Cree women compared with men (24), which could modulate several other intermediate metabolic pathways related to development of diabetes. Whatever the mechanism, the findings suggest that gender should be accounted for in future research analyses and possibly in predictive diagnosis and clinical decision-making in the Oji-Cree.

The findings also confirm the earlier impression that the diabetes in the Oji-Cree had more than one genetic determinant. Of the 179 overall affected subjects in the present study, 55 (30.7%) had HNF1A S319 and an additional 32 (17.9%) had PPARG A12. Thus, almost 50% of all affected subjects and more than 60% of young affected subjects had either PPARG A12 or HNF1A S319. In addition, the odds of being affected for a subject who carried at least one of these markers was about twice as high as for a subject who carried neither. Furthermore, the odds of being unaffected for a subject who carried neither marker are about twice as high as for a subject who carried at least one. These relationships suggest the potential of diagnostic utility for this combination of markers. There are still obviously gaps in diagnostic specificity and sensitivity, since many affected subjects had neither marker and some unaffected subjects had at least one. These gaps might be narrowed by further research into the genetic and nongenetic factors that underlie type 2 diabetes in the Oji-Cree.

In summary, we report the association between type 2 diabetes in the Oji-Cree of Sandy Lake with PPARG A12, which represents the second associated candidate gene variant in this population. This suggests that the diabetes susceptibility among Sandy Lake Oji-Cree is at least oligogenic. The association with affected status was more significant for women than men. Also, the presence of the PPARG A12 allele was associated with significant differences in the age-of-onset of diabetes in women and in the overall study sample. The observed gender specificity could have been related to the general tendency of Oji-Cree women to develop obesity at younger ages than men or to other gender-specific factors. It would be important to define the mechanistic basis for the association of diabetes with both HNF1A S319 and PPARG A12 through cellular and/or physiological experiments. The ability to stratify Oji-Cree subjects according to their HNF1A and/or PPARG genotype could be helpful in future prospective clinical studies of the natural history and interventions for diabetes.


    Acknowledgments
 
We acknowledge the chief and council of the community of Sandy Lake, the Sandy Lake community surveyors, the Sandy Lake nurses, the staff of the University of Toronto Sioux Lookout programme, and the Department of Clinical Epidemiology of the Samuel Lunenfeld Research Institute.


    Footnotes
 
1 Supported by grants from the NIH (DK44597-01), the Ontario Ministry of Health (#04307), the Medical Research Council of Canada (MT13430), the Canadian Diabetes Association (in honor of Rheta Maude Gilbert), the Canadian Genetic Diseases Network, and the Blackburn Group. Back

2 Career Investigator of the Heart and Stroke Foundation of Ontario. Back

3 Career Investigator of the Ontario Ministry of Health. Back

4 Supported by Health Canada through a National Health Research and Development Program Research Training Award. Back

Received October 28, 1999.

Revised January 19, 2000.

Accepted January 24, 2000.


    References
 Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 

  1. Hegele RA, Cao H, Harris SB, Hanley AJG, Zinman B. 1999 The hepatic nuclear factor-1{alpha} G319S variant is associated with early onset type 2 diabetes in Canadian Oji-Cree. J Clin Endocrinol Metab. 84:1077–1082.[Abstract/Free Full Text]
  2. Hegele RA, Cao H, Harris SB, Hanley AJG, Zinman B. 1999 HNF-1{alpha} G319S: a private mutation in Oji-Cree associated with type 2 diabetes. Diabetes Care. 22:524.
  3. Kliewer SA, Willson TM. 1998 The nuclear receptor PPAR{gamma}—bigger than fat. Curr Opin Genet Dev. 8:576–581.[CrossRef][Medline]
  4. Ribon V, Johnson JH, Camp HS, Saltiel AR. 1998 Thiazolidinediones, and insulin resistance: peroxisome proliferator activated receptor {gamma} activation stimulates expression of the CAP gene. Proc Natl Acad Sci USA. 95:14751–14756.[Abstract/Free Full Text]
  5. Spiegelman BM. 1998 PPAR-{gamma}: adipogenic regulator, and thiazolidinedione receptor. Diabetes. 47:507–514.[Abstract]
  6. Beamer BA, Negri C, Yen C-J, et al. 1997 Chromosomal localization, and partial genomic structure of the human peroxisome proliferator activated receptor-{gamma} (hPPAR-{gamma}) gene. Biochem Biophys Res Commun. 233:756–759.[CrossRef][Medline]
  7. Yen C-J, Beamer BA, Negri C, et al. 1997 Molecular scanning of the human peroxisome proliferator activated receptor {gamma} (PPAR{gamma}) gene in diabetic Caucasians: identification of a Pro12Ala PPAR-{gamma}2 missense mutation. Biochem. Biophys Res Commun. 241:270–274.[CrossRef][Medline]
  8. Beamer BA, Yen CJ, Andersen RE, et al. 1998 Association of the pro12ala variant in the peroxisome proliferator-activated receptor-{gamma}-2 gene with obesity in two Caucasian populations. Diabetes. 47:1806–1808.[Medline]
  9. Deeb SS, Fajas L, Nemoto M, et al. 1998 A Pro12Ala substitution in PPAR{gamma}2 associated with decreased receptor activity, lower body mass index and improved insulin sensitivity. Nat Genet. 20:284–287.[CrossRef][Medline]
  10. Mancini FP, Vaccaro O, Sabatino L, et al. 1999 Pro. 12Ala substitution in the peroxisome proliferator-activated receptor is not associated with type 2 diabetes. Diabetes48 :1466–1468.
  11. Hegele RA, Sun F, Harris SB, Anderson C, Hanley AJG, Zinman B. 1999 Genome-wide scanning for type 2 diabetes susceptibility in Canadian Oji-Cree, using 190 microsatellite markers. J Hum Genet. 44:10–14.[CrossRef][Medline]
  12. Harris SB, Gittelsohn J, Hanley AJG, et al. 1997 The prevalence of NIDDM, and associated risk factors in native Canadians. Diabetes Care. 20:185–197.[Abstract]
  13. Gittelsohn J, Wolever TM, Harris SB, Harris-Giraldo R, Hanley AJ, Zinman B. 1998 Specific patterns of food consumption, and preparation are associated with diabetes and obesity in a native Canadian community. J Nutr. 128:541–547.[Abstract/Free Full Text]
  14. Hegele RA, Harris SB, Hanley AJ, Sadikian S, Connelly PW, Zinman B. 1996 Genetic variation of intestinal fatty acid-binding protein associated with variation in body mass in aboriginal Canadians. J Clin Endocrinol Metab. 81:4334–4337.[Abstract]
  15. Hegele RA, Connelly PW, Scherer SW, et al. 1997 Paraoxonase-2 gene (PON2) G148 variant associated with elevated fasting plasma glucose in noninsulin-dependent diabetes mellitus. J Clin Endocrinol Metab. 82:3373–3377.[Abstract/Free Full Text]
  16. Hegele RA, Connelly PW, Scherer SW, et al. 1997 Paraoxonase-2 G148 variant in an aboriginal Canadian girl with non-insulin-dependent diabetes. Lancet 350:785.
  17. Hegele RA, Harris SB, Hanley AJ, Azouz H, Connelly PW, Zinman B. 1998 Absence of association between genetic variation of the ß 3-adrenergic receptor and metabolic phenotypes in Oji-Cree. Diabetes Care. 21:851–854.[Abstract]
  18. Hegele RA, Wolever TM, Hanley AJ, Harris SB, Zinman B. 1998 Methylenetetra-hydrofolate reductase gene, dietary folate, NIDDM, and atherosclerosis in Canadian Oji-Cree. Diabetes Care. 21:322–323.
  19. Hegele RA, Harris SB, Zinman B. 1998 Hemochromatosis and diabetes mellitus. Ann Intern Med. 129:587.[Free Full Text]
  20. World Health Organization (WHO) Expert Committee on Diabetes Mellitus. 1980 Second report. Geneva: WHO Technical report series; 646.
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