Marcadores genéticos e auto-imunes do diabetes melito tipo 1: da teoria para a prática

Silva, Maria Elizabeth Rossi da; Mory, Denise Barreto; Davini, E.

doi:10.1590/s0004-27302008000200004

Cited by 17 publications

(18 citation statements)

References 40 publications

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“…10 However, in the present study, we observed that 63.8% of a study population that had been diagnosed with DM1 more than three years previously and was on insulin therapy was anti-GAD-positive.…”

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confidence: 64%

Frequency of the anti-glutamic acid decarboxylase immunological marker in patients with diabetes duration longer than three years in southern Brazil

et al. 2011

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CONTEXT AND OBJECTIVE: The anti-GAD (glutamic acid decarboxylase) antibody is considered to be an important marker for type 1 diabetes mellitus (DM1), with frequency that varies depending on the population studied and the duration of the disease. Therefore, the aim of this study was to determine the frequency of this autoantibody in a group of patients in southern Brazil with DM1 that had been diagnosed more than three years previously. DESIGN AND SETTING: Analytical cross-sectional study with a control group conducted at the Biomedicine Laboratory of Universidade Feevale. METHODS: This study was conducted between June 2007 and December 2008, and 109 individuals were enrolled during this period. Fifty-eight were DM1 patients and 51 were individuals free from DM1 and without any history of diabetes, who constituted the control group. RESULTS: In the DM1 group, the mean age was 27 ± 1.7 years and 50% were men. The mean fasting blood glucose in the DM1 group was 208 ± 15 mg/dl and mean HbA1c (glycosylated hemoglobin) was 8.7 ± 0.25%. In the control group, the mean fasting blood glucose and HbA1c were 82 mg/dl and 5.0% respectively. Thirty-seven individuals with DM1 (63.8%) were positive for anti-GAD, and this proportion was significantly larger than in the control group. CONCLUSIONS: These results show the high prevalence of anti-GAD in the population of diabetic patients in southern Brazil, thus indicating that the antibody was still present a long time after the disease had been diagnosed.

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confidence: 64%

Frequency of the anti-glutamic acid decarboxylase immunological marker in patients with diabetes duration longer than three years in southern Brazil

et al. 2011

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“…Previous studies conducted in Brazil with small sample sizes have shown inter-regional differences in the frequencies of the HLA-DR and -DQ alleles and of the other risk polymorphisms for T1D3. Furthermore, differences in populations referred to as Caucasian in other countries were also observed14.…”

Section: Discussionmentioning

confidence: 89%

The influence of population stratification on genetic markers associated with type 1 diabetes

Gomes

Santos

Semzezem

et al. 2017

Sci Rep

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Ethnic admixtures may interfere with the definition of type 1 diabetes (T1D) risk determinants. The role of HLA, PTPN22, INS-VNTR, and CTLA4 in T1D predisposition was analyzed in Brazilian T1D patients (n = 915), with 81.7% self-reporting as white and 789 controls (65.6% white). The results were corrected for population stratification by genotyping 93 ancestry informative markers (AIMs) (BeadXpress platform). Ancestry composition and structural association were characterized using Structure 2.3 and STRAT. Ethnic diversity resulted in T1D determinants that were partially discordant from those reported in Caucasians and Africans. The greatest contributor to T1D was the HLA-DR3/DR4 genotype (OR = 16.5) in 23.9% of the patients, followed by -DR3/DR3 (OR = 8.9) in 8.7%, -DR4/DR4 (OR = 4.7) in 6.0% and -DR3/DR9 (OR = 4.9) in 2.6%. Correction by ancestry also confirmed that the DRB1*09-DQB1*0202 haplotype conferred susceptibility, whereas the DRB1*07-DQB1*0202 and DRB1*11-DQB1*0602 haplotypes were protective, which is similar to reports in African-American patients. By contrast, the DRB1*07-DQB1*0201 haplotype was protective in our population and in Europeans, despite conferring susceptibility to Africans. The DRB1*10-DQB1*0501 haplotype was only protective in the Brazilian population. Predisposition to T1D conferred by PTPN22 and INS-VNTR and protection against T1D conferred by the DRB1*16 allele were confirmed. Correcting for population structure is important to clarify the particular genetic variants that confer susceptibility/protection for T1D in populations with ethnic admixtures.

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“…Skin color is poorly correlated with genetic ancestry in the Brazilian population and therefore self-reported race can be inaccurate for genetic studies [Pena, et al 2011]. Early genetic studies of type 1 diabetes (T1D) in Brazilians reported geographic variability in HLA-DR and HLA-DQ allele frequencies, two genetic loci strongly associated with T1D in Europeans [Silva, et al 2008; Thomson, et al 2007]. In a study accounting for PS, Gomes et al identified a novel protective haplotype DRB1*10-DQB1*0501 [Gomes, et al 2017].…”

Section: Key Conceptsmentioning

confidence: 99%

Population Stratification in Genetic Association Studies

et al. 2017

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Population stratification (PS) is a primary consideration in studies of the genetic determinants of human traits. Failure to control for it may lead to confounding, causing a study to fail for lack of significant results or resources to be wasted following false positive signals. Here we review historical and current approaches for addressing PS when performing genetic association studies in human populations. We describe methods for detecting the presence of PS including global and local ancestry methods. We also describe approaches for accounting for PS when calculating association statistics, such that measures of association are not confounded. Many traits are being examined for the first time in minority populations, populations that may inherently feature PS.

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Marcadores genéticos e auto-imunes do diabetes melito tipo 1: da teoria para a prática

Cited by 17 publications

References 40 publications

Frequency of the anti-glutamic acid decarboxylase immunological marker in patients with diabetes duration longer than three years in southern Brazil

Frequency of the anti-glutamic acid decarboxylase immunological marker in patients with diabetes duration longer than three years in southern Brazil

The influence of population stratification on genetic markers associated with type 1 diabetes

Population Stratification in Genetic Association Studies

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