• Genomics & Informatics
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• v.4 no.2
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• pp.51-56
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• 2006

In planning a genetic association study, it is necessary to determine the number of samples to be collected for the study in order to achieve sufficient power to detect the hypothesized effect. The case-control design is increasingly used for genetic association studies due to the simplicity of its design. We review the methods for the sample size and power calculations in case-control genetic association studies between a marker locus and a disease phenotype.

• International Journal of Human Ecology
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• v.11 no.2
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• pp.15-23
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• 2010

This study explored genetic and environmental contributions to optimism, depressive symptoms, and the association between the two using a genetically informative sample from the Nonshared Environment and Adolescent Development project (NEAD: D. Reiss; J. M. Neiderhiser; E. M. Hetherington; & R. Plomin, 2000. At Time 1 of the longitudinal NEAD study, the sample consisted of 720 samesex twins and sibling pairs from two parent families. The study used parent, adolescent, and observer ratings of depressive symptoms as well as adolescent ratings of optimism. The results revealed that genetic influences explained approximately half of the variability in optimism and depressive symptoms. Nonshared environmental influences also substantially contributed to optimism and depressive symptoms. Bivariate genetic analyses (which partitioned the covariance between optimism and depressive symptoms into genetic and environmental components) indicated that genetic influences accounted for a moderate percentage of the association.

• Genomics & Informatics
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• v.8 no.3
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• pp.142-149
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• 2010

In recent years, genome-wide association (GWA) studies have successfully led to many discoveries of genetic variants affecting common complex traits, including height, blood pressure, and diabetes. Although GWA studies have made much progress in finding single nucleotide polymorphisms (SNPs) associated with many complex traits, such SNPs have been shown to explain only a very small proportion of the underlying genetic variance of complex traits. This is partly due to that fact that most current GWA studies have relied on single-marker approaches that identify single genetic factors individually and have limitations in considering the joint effects of multiple genetic factors on complex traits. Joint identification of multiple genetic factors would be more powerful and provide a better prediction of complex traits, since it utilizes combined information across variants. Recently, a new statistical method for joint identification of genetic variants for common complex traits via the elastic-net regularization method was proposed. In this study, we applied this joint identification approach to a large-scale GWA dataset (i.e., 8842 samples and 327,872 SNPs) in order to identify genetic variants of obesity for the Korean population. In addition, in order to test for the biological significance of the jointly identified SNPs, gene ontology and pathway enrichment analyses were further conducted.

• Animal cells and systems
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• v.8 no.1
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• pp.41-47
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• 2004

The kallikrein-kinin system affects regulation of blood pressure, and genes encoding for the components of this system have been considered as good candidates for hypertension. To evaluate the relationship between genetic polymorphisms of candidate genes involved in this system and hypertension, we performed case-control studies using genetic markers in Korean normotensives and hypertensives, respectively. By association study, there was a marginal association with hypertension in AA genotype distribution of A1789G polymorphism in the hKLK1 gene (P=0.0754). Thus, this genetic polymorphism may weakly contribute to the susceptibility to hypertension in Koreans. We also observed that significant linkage disequilibrium exists among three polymorphic sites in the hKLK1 gene studied, suggesting that the three genetic polymorph isms can be useful as genetic markers in clinical association studies. Further studies using larger sample sizes and more genetic markers will be needed to clarify genetic influence of kallikrein-kinin system for hypertension.

• Biomedical Science Letters
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• v.23 no.2
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• pp.89-95
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• 2017

Tuberculosis (TB), mainly disseminated by infection of the respiratory tract, remains an unsolved community health problem by Mycobacterium tuberculosis (MTB). However, because of the different susceptibility to MTB, people infected with MTB do not all develop TB. These differences of disease arise from individual genetic susceptibility as well as the property of the microorganisms itself. CD226, one of the genetic factors that influences TB, interact with its ligand PVR and ITGB2. It is induced various cellular responses that contribute multiple innate and adaptive responses. In a previous study, CD226 enhanced immune efficacy induced by Ag85A DNA vaccination that is secreted protein by MTB. The aim of this study was to investigate the association between six genetic polymorphisms of CD226 gene and TB status with Korean population. Our results show that two SNPs of CD226 were identified to associate with tuberculosis. The highest significant SNP was rs17081766 (OR=0.70, CI: 0.54~0.90, $P=5.4{\times}10^{-3}$). According to this study, polymorphisms of CD226 gene affect the outbreak of TB in MTB-infected patients. It is suggested that polymorphism of other genes also associated with immune responses results in susceptibility to TB. The results from this study suggest that not only the characteristics of the microorganism itself but also the genetic background of the individual may affect progression of TB in MTB-infected patients.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.341-345
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• 2011

Genetic association study has been progressed in medicine along with advance in genetic technology. It focused on the individual differences in genotype due to errors occurring during DNA duplication, which can cause vulnerability to specific diseases. Polymorphism defines the varieties in phenotype due to those genetic variations. Polymorphism due to change in one DNA base sequence is called as a Single Nucleotide Polymorphism. In the near future, the evaluation of relative risk to specific disease according to SNP will be essential part of fundamental of medicine for the diagnosis, treatment and prevention. Dental caries and periodontal diseases has been first subject to genetic association study in dentistry and broaden out to other areas like bone formation and resorption. This article presents the current state of genetic association study and its application to dentistry.

• Korean Journal of Biological Psychiatry
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• v.3 no.1
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• pp.14-21
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• 1996

Molecular genetic approaches contribute to the understanding of the underlying genetic mechanism for schizophrenia. Currently genetic evidence rests on molecular genetic methods. However, the result are contradictory and somewhat confusing due to genetic heterogeneity, incomplete penetrance, misspecification of genetic model. It is expected that molecular genetics could provide key answers to the genetic cause of schizophrenia. The purpose of this article is to call attention of the readers to heterogeneity, linkage, association, basic molecular genetic methods and genetic markers and to the need far further research. It is the author's hope thai continuous research on the molecular genetics con provide clinicians with better understanding of the schizophrenia.

• Animal Bioscience
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• v.37 no.5
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• pp.807-816
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• 2024

Objective: This study aims to identify the significant regions and candidate genes of growth-related traits (adjusted backfat thickness [ABF], average daily gain [ADG], and days to 90 kg [DAYS90]) in Korean commercial GGP pig (Duroc, Landrace, and Yorkshire) populations. Methods: A genome-wide association study (GWAS) was performed using single-nucleotide polymorphism (SNP) markers for imputation to Illumina PorcineSNP60. The BayesB method was applied to calculate thresholds for the significance of SNP markers. The identified windows were considered significant if they explained ≥1% genetic variance. Results: A total of 28 window regions were related to genetic growth effects. Bayesian GWAS revealed 28 significant genetic regions including 52 informative SNPs associated with growth traits (ABF, ADG, DAYS90) in Duroc, Landrace, and Yorkshire pigs, with genetic variance ranging from 1.00% to 5.46%. Additionally, 14 candidate genes with previous functional validation were identified for these traits. Conclusion: The identified SNPs within these regions hold potential value for future marker-assisted or genomic selection in pig breeding programs. Consequently, they contribute to an improved understanding of genetic architecture and our ability to genetically enhance pigs. SNPs within the identified regions could prove valuable for future marker-assisted or genomic selection in pig breeding programs.

• Animal Bioscience
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• v.35 no.7
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• pp.955-963
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• 2022

Objective: The aim of this study was to estimate genetic parameters for 305-day cumulative milk yield and components, growth, and reproductive traits in Guzerá cattle. Methods: The evaluated traits were 305-day first-lactation cumulative yields (kg) of milk (MY305), fat (FY305), protein (PY305), lactose (LY305), and total solids (SY305); age at first calving (AFC) in days; adjusted scrotal perimeter (cm) at the ages of 365 (SP365) and 450 (SP450) days; and adjusted body weight (kg) at the ages of 210 (W210), 365 (W365), and 450 (W450) days. The (co)variance components were estimated using the restricted maximum likelihood method for single-trait, bi-trait and tri-trait analyses. Contemporary groups and additive genetic effects were included in the general mixed model. Maternal genetic and permanent environmental effects were also included for W210. Results: The direct heritability estimates ranged from 0.16 (W210) to 0.32 (MY305). The maternal heritability estimate for W210 was 0.03. Genetic correlation estimates among milk production traits and growth traits ranged from 0.92 to 0.99 and from 0.92 to 0.99, respectively. For milk production and growth traits, the genetic correlations ranged from 0.33 to 0.56. The genetic correlations among AFC and all other traits were negative (-0.43 to -0.27). Scrotal perimeter traits and body weights showed genetic correlations ranging from 0.41 to 0.46, and scrotal perimeter and milk production traits showed genetic correlations ranging from 0.11 to 0.30. The phenotypic correlations were similar in direction (same sign) and lower than the corresponding genetic correlations. Conclusion: These results suggest the viability and potential of joint selection for dairy and beef traits in Guzerá cattle, taking into account reproductive traits.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.3
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• pp.309-313
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• 2008

The insulin-like growth factor binding protein 3 (IGFBP3) has been investigated as a candidate gene for growth promoting effects in beef cattle and a modulator of IGF bioactivity. Previously, we have reported twenty two sequence variants discovered in Korean native cattle (Hanwoo). In this study, we examined the association between gene-specific polymorphisms of IGFBP3 and cold carcass weight (CW) and marbling score (MS) among Korean native cattle. Among twenty two polymorphisms, four common polymorphic sites (-854G>C, -100G>A, +421G>T and +3863C>A) were genotyped in our beef cattle (n = 437). Statistical analysis revealed that one common polymorphism in the promoter region (-854G>C) showed putative associations with MS (p = 0.03). IGFBP3 variation/haplotype information analyzed in this study will provide valuable information into strategies for the production of a commercial line of beef cattle.