• 응용통계연구
• /
• 제21권1호
• /
• pp.81-94
• /
• 2008

전달불균형 검정법(transmission and disequilibrium test)과 같은 가계중심(family-based) 검정법들은 질병 관련 유전자를 찾는 데 매우 유용한 방법으로 알려져 있다. 사례-대조군 연구와 달리 가계중심 검정법들은 집단혼합(population admixture)으로 인한 영향을 받지 않기 때문에 질병 관련 유전자와 표지자(marker) 사이의 집단 혼합으로 인한 가짜 연관성(spurious association)에 노출될 위험이 없다. 가계중심 검정법들은 대체로 표지자에 대한 부모의 유전자형(genotype) 정보를 필요로 한다. 그러나 고령층에서 발병하는 질병의 경우에는 발단자(proband) 부모의 유전자형을 구할 수 없는 상황에 종종 마주치게 된다. 본 논문에서는 이런 어려움을 극복하기 위해 부모의 유전자형 대신 질병에 노출되지 않은 발단자 형제나 자매의 유전자형을 이용한 검정법을 제안하고자 한다. 이를 위해 먼저 가능한 모든 일배체형(haplotype)에 대해 Mantel-Haenszel 형태의 통계량을 정의하고 그것에 기초한두 가지 검정통계량을 제안하였다. 모의실험 결과, 제안한 검정법은 집단 혼합으로부터 로버스트하고 유전 양식(mode of inheritance)에 관계 없이 상대위험(relative risk)이 증가함에 따라 단조적으로 증가하는 검정력을 갖는 것으로 나타났다. 제안한 검정법을 연세대학교 심혈관계질환 유전체연구센터로부터 수집한 자료에 적용하고 그 결과를 고찰하였다.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2004년도 추계학술발표회
• /
• pp.90-91
• /
• 2004

• Asian-Australasian Journal of Animal Sciences
• /
• 제18권11호
• /
• pp.1548-1551
• /
• 2005

The leptin, an anti-obesity protein, is a hormone protein expressed and secreted mainly from adipocyte tissue, and involved in regulation of body weight, food intake and energy metabolism. In an effort to discover polymorphism(s) in genes whose variant(s) might be implicated in phenotypic traits of growth, we have sequenced exons and their boundaries of leptin gene including 1,000 bp upstream of promoter region with twenty-four unrelated Korean cattle. Fifty-seven sequence variants were identified: fourteen in 5' flanking region, twenty-seven in introns, eight in exons, and eight in 3' flanking region. By pair-wise linkage analysis among polymorphisms, ten sets of SNPs were in absolute linkage disequilibrium (LD) (|D'| = 1 and $r^2$ = 1). Among variants identified, thirty-six SNPs were newly identified, and twenty-one SNPs, which were reported in other breeds, were also confirmed in Korean cattle. The allele frequencies of variants were quite different among breeds. The information from SNPs of bovine leptin gene could be useful for further genetic studies of this gene.

• 응용통계연구
• /
• 제21권2호
• /
• pp.221-231
• /
• 2008

본 연구는 통상적인 일일자료 대신 주간자료를 사용하여 구제금융시대 전후 한국과 미국의 주식시장 동조화논란에 대해 통계적으로 검정해 보았다. 특히 양국의 주가간에 장기적 균형관계가 존재할 때 단기적 불균형에서 장기균형으로 복귀하는 성향에 대해 기간별로 어떤 차이점이 있는가를 추정하였다. 양국의 개별 주가간 장기적 균형관계는 구제금융기간이 시작되면서 뚜렷해지고 그 이후는 더욱 다양해지는 것으로 나타났다. 특히 구제금융기간이 끝나기 전까지는 단기간의 불균형이 해소되는 속도가 느렸지만 기간 종료 이후는 장기균형이 빠르게 회복된다는 사실이 일관성있게 추정되고 있다.

• Genomics & Informatics
• /
• 제5권4호
• /
• pp.152-160
• /
• 2007

Most common diseases are caused by multiple genetic and environmental factors. Among the genetic factors, single nucleotide polymorphisms (SNPs) are common DNA sequence variations in individuals and can serve as important genetic markers. Recently, investigations of gene-based and whole genome-based SNPs have been applied to association studies for marker discovery. However, SNPs are so population-specific that the association needs to be verified. Fifty-five genes and 384 SNPs were selected based on association with disease. Genotypes of 337 SNPs in candidate genes were determined using Illumina Sentrix Array Matrix (SAM) chips by an allele-specific extension method in 364 unrelated Korean individuals. Allelic frequencies of SNPs were compared with those of other populations obtained from the International HapMap database. Minor allele frequencies, linkage disequilibrium blocks, tagSNPs, and haplotypes of functional candidate SNPs in 55 genetic disease-associated genes were provided. Our data may provide useful information for the selection of genetic markers for gene-based genetic disease-association studies of the Korean population.

• Archives of Pharmacal Research
• /
• 제29권12호
• /
• pp.1132-1139
• /
• 2006

Single nucleotide polymorph isms (SNPs) in the MDR1 gene that are responsible for drug efflux can cause toxicity. Therefore, this study determined the SNPs of the Korean MDR1 gene, and analyzed the haplotypes and a linkage disequilibrium (LD) of the SNPs determined. The frequency of 9 SNPs from the MDR1 gene was determined by PCR-RFLP analyses of 100 to 500 healthy individuals. The frequcies of the SNPs were C3435T (47.7%), G2677T (37.6%), G2677A (4.4%), T1236C (21.7%), T129C (8%), A2956G (2.5%), T307C (1.5%), A41aG (9.2%), C145G (0%), and G4030C (0%). Analyses of the haplotype structure and an estimation of the LD of the combined polymorph isms demonstrated that the frequency of the 1236T-2677G-3435T haplotype is much higher in Koreans (14.1%) than in Chinese and western black Africans and the C3435T SNP in Koreans appears to have LD with T129C in Koreans for the first time. These results provide insight into the genetic variation of MDR1 in Koreans, and demonstrated the possibility of a new LD in this gene.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권12호
• /
• pp.1702-1705
• /
• 2006

A simulation study was conducted to evaluate a fine-mapping method exploiting population-wide linkage disequilibrium. Data were simulated according to the pedigree structure based on a large paternal half-sib family population with a total of 1,034 or 2,068 progeny. Twenty autosomes of 100 cM were generated with 5 cM or 1 cM marker intervals for all founder individuals in the pedigree, and marker alleles and a number of quantitative trait loci (QTL) explaining a total of 70% phenotypic variance were generated and randomly assigned across the whole chromosomes, assuming linkage equilibrium between the markers. The founder chromosomes were then descended through the pedigree to the current offspring generation, including recombinants that were generated by recombination between adjacent markers. Power to detect QTL was high for the QTL with at least moderate size, which was more pronounced with larger sample size and denser marker map. However, sample size contributed much more significantly to power to detect QTL than map density to the precise estimate of QTL position. No QTL was detected on the test chromosomes in which QTL was not assigned, which did not allow detection of false positive QTL. For the multiple QTL that were closely located, the estimates of the QTL positions were biased, except when the QTL were located on the right marker positions. Our fine mapping simulation results indicate that construction of dense maps and large sample size is needed to increase power to detect QTL and mapping precision for QTL position.

• 응용통계연구
• /
• 제15권1호
• /
• pp.85-105
• /
• 2002

본 연구에서는 유전자 검사자료에서 각 유전자좌내 및 유전자좌간의 대립형질들간의 관계를 파악하기 위한 탐색적 방법을 고려하였다. 이를 위해 유전자데이터를 재배열한 후 대응분석 및 다중대응분석의 알고리즘을 적용하여 이를 수량화, 그래프화하는 방법 및 대응행렬도를 적용한 방법을 제안하였다 이러 한 수량화 및 그래프 결과가 하디-와인버그 평형검정 및 연관균형검정 결과와 어떤 관계가 있는지 알아보고 실제 한국인 집단에 대한 STR 유전자좌 자료를 이용하여 결과를 비교하였다.

• Communications for Statistical Applications and Methods
• /
• 제24권6호
• /
• pp.663-671
• /
• 2017

Some genetic association tests include an unidentifiable nuisance parameter under the null hypothesis of no association. When the mode of inheritance (MOI) is not specified in a case-control design, the Cochran-Armitage (CA) trend test contains an unidentifiable nuisance parameter. The transmission disequilibrium test (TDT) in a family-based association study that includes the unaffected also contains an unidentifiable nuisance parameter. The hypothesis tests that include an unidentifiable nuisance parameter are typically performed by taking a supremum of the CA tests or TDT over reasonable values of the parameter. The p-values of the supremum test statistics cannot be obtained by a normal or chi-square distribution. A common method is to use a Davies's upper bound of the p-value instead of an exact asymptotic p-value. In this paper, we provide a unified sine-cosine process expression of the CA trend test that does not specify the MOI and the TDT that includes the unaffected. We also present a closed form expression of the exact asymptotic formulas to calculate the p-values of the supremum tests when the score function can be written as a linear form in an unidentifiable parameter. We illustrate how to use the derived formulas using a pharmacogenetics case-control dataset and an attention deficit hyperactivity disorder family-based example.

• Asian-Australasian Journal of Animal Sciences
• /
• 제32권1호
• /
• pp.58-62
• /
• 2019

Objective: The oxidized low density lipoprotein receptor 1 (OLR1) gene plays an important role in the degradation of oxidized low-density lipoprotein and adipocyte proliferation in mammals. For this reason, we aimed at investigating the association of OLR1 gene polymorphisms with carcass quality traits in Chinese Qinchuan cattle. Methods: The single nucleotide polymorphism (SNP) was identified in the 3' untranslated region of bovine OLR1 gene by DNA sequencing. In addition, the haplotype frequency and linkage disequilibrium estimates of three SNPs were evaluated in 520 individuals. Results: Results indicated that the studied three SNPs were within the range of moderate genetic diversity (0.25< polymorphism information content<0.5). Haplotype analysis of three SNPs showed that ten different haplotypes were identified, but only five haplotypes were listed as those with a frequency of <0.05 were excluded. The Hap3 ($-G_1T_2C_3-$) had the highest haplotype frequency (42.10%). Linkage disequilibrium analysis showed that the three SNPs had a low linkage ($r^2<0.001$). The T10588C and C10647T were significantly associated with backfat thickness and intramuscular fat content in Qinchuan cattle. Conclusion: Based on our results, we believe that the OLR1 gene could be a strong candidate gene for influencing carcass quality traits in Qinchuan cattle.