Younyoung Kim

The Gene Encoding Transforming Growth Factor β1 Confers Risk of Ischemic Stroke and Vascular Dementia

Background and Purpose— Transforming growth factor-&bgr;1 (TGF-&bgr;1) is an anti-inflammatory cytokine that plays an important role in cerebrovascular pathophysiology with protective activity against ischemia-induced neuronal death. We investigated the association of the polymorphism in TGFB1 with ischemic stroke and vascular dementia. Methods— Three sequence variants in and around promoter and exons of TGFB1 gene were identified in 30 Koreans. Pro10Leu was selected for association study, and then control subjects (n=207) and patients with ischemic stroke (n=271) and vascular dementia (n=207) were screened. Results— Subjects carrying Leu/Leu were susceptible to both ischemic stroke (odds ratio [OR]=1.63; P<0.05) and vascular dementia (OR=1.88; P<0.01). Analyses with stroke subtypes showed a strong association with small vessel occlusion (SVO, n=110; OR=2.07; P<0.01). Further analysis of SVO data partitioned by gender revealed the female-specific association with Pro10Leu (OR=2.70; P<0.05). Conclusions— The Pro10Leu of TGFB1 might be a risk factor of ischemic stroke and vascular dementia, especially for SVO in females.

Klotho is a genetic risk factor for ischemic stroke caused by cardioembolism in Korean females.

An aging-suppressor gene, klotho, is a candidate factor for vascular disease because its deficiency leads to impaired endothelium-dependent vasodilation and impaired angiogenesis. We investigated the association of polymorphisms in klotho with ischemic stroke. We searched for sequence variants in promoter and exons of klotho gene. For the association study, selected variants were genotyped in control subjects and in patients with ischemic stroke and vascular dementia. The association with ischemic stroke was further investigated with its subtypes classified based on Trial of Org 10172 in Acute Stroke Treatment (TOAST). No significant association was observed for both G-395A and C1818T with ischemic stroke and vascular dementia (P>0.05). The analysis with subtypes of ischemic stroke revealed the associations that the A allele of G-395A increased the risk of cardioembolic stroke (CE, OR=2.60; P=0.006), and subjects carrying the A allele were susceptible to CE in both of dominant (AA+GA versus GG; OR=2.50; P=0.046) and recessive (AA versus GA+GG; OR=6.52; P=0.007) models. Further analysis of data partitioned by gender showed that the associations of G-395A with CE only existed in women (A versus G; OR=4.33; P=0.002), AA+GA versus GG; OR=5.68; P=0.014, and AA versus GA+GG; OR=9.07; P=0.012), but the significance disappeared in men (P>0.05). The sequence variant of G-395A in klotho might be a genetic risk factor for CE in females.

Genome-wide association study reveals five nucleotide sequence variants for carcass traits in beef cattle

Genetic associations of nucleotide sequence variants with carcass traits in beef cattle were investigated using a genome-wide single nucleotide polymorphism (SNP) assay. Three hundred and thirteen Korean cattle were genotyped with the Illumina BovineSNP50 BeadChip, and 39,129 SNPs from 311 animals were analysed for each carcass phenotype after filtering by quality assurance. Five sequence markers were associated with one of the meat quantity or quality traits; rs109593638 on chromosome 3 with marbling score, rs109821175 on chromosome 11 and rs110862496 on chromosome 13 with backfat thickness (BFT), and rs110228023 on chromosome 6 and rs110201414 on chromosome 16 with eye muscle area (EMA) (P < 1.27 × 10(-6) , Bonferonni P < 0.05). The ss96319521 SNP, located within a gene with functions of muscle development, dishevelled homolog 1 (DVL1), would be a desirable candidate marker. Individuals with genotype CC at this gene appeared to have increased both EMA and carcass weight. Fine-mapping would be required to refine each of the five association signals shown in the current study for future application in marker-assisted selection for genetic improvement of beef quality and quantity.

Haplotype analysis of single nucleotide polymorphisms in VEGF gene for vascular dementia

A case‐control study was performed to identify single nucleotide variants of vascular endothelial growth factor (VEGF) gene associated with vascular dementia. Seven SNPs in promoter, 5′‐UTR, 3′‐UTR, and introns of VEGF gene were identified in 24 Koreans. Three of them, −1154G/A, −7C/T, and 13553C/T, were selected based on allele frequency and linkage disequilibrium (LD), and genotyped in 207 vascular dementia patients and 207 control subjects. Significant association with vascular dementia was not shown (P > 0.05) in the alleles and genotypes of single locus. Subsequent analysis of composing VEGF risk haplotypes associated with vascular dementia was performed with maximum likelihood estimates of their possible haplotypes employing the expectation‐maximization (EM) algorithm. Of three‐locus haplotypes, only GTC was significantly associated with vascular dementia, conferring a risk of 1.87 (P < 0.05). Of two‐locus haplotypes, the risk was observed with the nested forms of the risk haplotype GTC, that is, GT at the loci −1154G/A and −7C/T and TC at the loci −7C/T and 13553C/T (P < 0.05). Our findings suggested some interaction among −1154G/A, −7C/T, and 13553C/T variants in the determination of risk for vascular dementia.

Single nucleotide variants in the β2-adrenergic and β3-adrenergic receptor genes explained 18.3% of adolescent obesity variation

AbstractAssociations of obesity with its candidate genes, β-adrenergic receptor genes (ADRBs), peroxisome proliferator-activated receptor-γ (PPARγ), and uncoupling proteins (UCPs) were studied in Korean adolescents. We analyzed the obesity-related phenotypes body mass index (BMI), percentage of body fat, plasma leptin and insulin levels, fasting glucose concentration, and plasma lipid profile in 329 teenagers to investigate the effects of seven single nucleotide variants 252G/A, 523C/A and 1053G/C in ADRB2; Trp64Arg in ADRB3; 161C/T in PPARγ; Ala55Val in UCP2; and 210C/T in UCP3. The 1053G/C polymorphism (P < 0.05) in the ADRB2 gene and the Trp64Arg polymorphism (P < 0.01) in the ADRB3 gene were associated with BMI after adjustment for dietary energy intake. Trp64Arg polymorphism also influenced percentage of body fat (P < 0.01) and plasma leptin level (P < 0.05). Furthermore, significant interaction effects between the 1053G/C and Trp64Arg polymorphisms were observed on BMI (P < 0.01). The polymorphisms of the ADRB2 and ADRB3 genes explained 4.3% and 10.1% of the variation on BMI, and the two loci effect, including their epistasis, explained 18.3%. We concluded that 1053G/C and Trp64Arg polymorphisms of the ADRB genes additively and interactively contributed to the variation of complex adolescent obesity.

Sequence variants of ACE, AGT, AT1R, and PAI-1 as genetic risk factors for vascular dementia

Sequence variants of angiotensin converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) T235M, angiotensin II type 1 receptor (AT1R) A1166C, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G were analyzed to see their genetic associations with vascular dementia as its candidate genetic risk factors involving renin-angiotensin and fibrin systems. While the ACE I/D, AT1R A1166C, and PAI-1 4G/5G did not contribute to the genetic susceptibility to vascular dementia (P>0.05), a significant association with vascular dementia was shown in the T235M polymorphism of AGT. The frequency of the M allele in patients was higher than in controls with the odds ratio (OR) estimate of 1.51 (P<0.05). In a dominant model, the TM+MM genotypes increased the risk of vascular dementia compared to the TT genotype (OR=2.01; P<0.001). The current results suggested that AGT T235M polymorphism might be a risk factor of vascular dementia.

Analysis of the SREBF2 gene as a genetic risk factor for vascular dementia.

A case‐control study was performed to examine the association between vascular dementia and the polymorphisms of the human gene encoding sterol regulatory element binding protein‐2 (SREBF2) that regulates cholesterol metabolism. The 16 genetic variants of SREBF2 were identified in 24 Koreans, and 5 out of 16 variants were genotyped in 207 vascular dementia patients and 207 control subjects. Significant association with vascular dementia was shown in 34995G/T with the GT genotype (odds ratio [OR] = 1.57; 95% CI = 1.04–2.37; P < 0.05) and the GG genotype (OR = 0.65; 95% CI = 0.44–0.96; P < 0.05). The CGC, the most common haplotype combined with three SNPs, 24489C/T, 34995G/T, and 68891C/T, was associated with the disease (OR = 0.72; 95% CI = 0.53–0.97; P < 0.05), and the individuals with the CGC might be less susceptible to vascular dementia than those carrying any haplotype including at least one minor allele. This study implied that the variants of SREBF2 might be genetic factors involved in the pathogenesis of vascular dementia.

Association of intronic sequence variant in the gene encoding spleen tyrosine kinase with susceptibility to vascular dementia.

Abstract Objectives. This study was aimed to identify a novel strong candidate gene for the susceptibility to vascular dementia (VaD) with comprehensive evidences. Methods. A preliminary genome-wide association study (GWAS) was conducted to identify nucleotide sequence variants susceptible to VaD. Literature-based analysis and network analysis were conducted to single out the best candidate gene, and its association was thoroughly examined over its whole sequences. Functions of the most probable variant were predicted by in silico alternative splicing analysis and evaluated by minigene assay. Results. The GWAS showed the most significant variant in spleen tyrosine kinase (SYK) gene. This concurred with the suggestions from both literature-based analysis and network analysis. Further association analysis over the whole SYK gene revealed that rs290227 in intron 8 was the most significant (P = 7.38 × 10−11). The subsequent in silico analysis showed that the intronic variant played potential roles in alternative splicing by skipping exon 8 or by truncating exon 9. It was validated by in vivo minigene assay that the G allele of rs290227 induced the delayed splicing. Conclusions. We suggested a novel association of the VaD susceptibility with an intronic variant of rs290227 in the SYK gene. Its G allele could render mature transcripts inappropriately by intron retention and thus lead to a genetic risk for VaD.

Heterogeneity of genetic associations of CDKAL1 and HHEX with susceptibility of type 2 diabetes mellitus by gender

We examined the genetic associations of previously identified sequence variants with type 2 diabetes mellitus (T2DM) and its potentially genetic heterogeneity by gender in a large-scale cohort. A total of 613 T2DM patients and 8221 control subjects from the Korea Association REsource (KARE) cohort were included in the analysis of genetic association of T2DM with 33 nucleotide polymorphic markers identified by previous studies. The association analysis was further conducted with data partitioned by gender. The association analysis resulted in five nucleotide sequence variants associated with the susceptibility of T2DM after Bonferonni correction (P<0.0015). One was located near the gene of hematopoietically expressed homeobox (HHEX), and the others were all in the gene of cyclin-dependent kinase 5 regulatory subunit-associated protein 1-like 1 (CDKAL1). Further analysis revealed that the sequence variant (rs5015480) near HHEX and two SNPs (rs7756992 and rs9465871) in CDKAL1 were associated with the susceptibility of T2DM in females (P<0.005), but not in males (P>0.005). We suggested heterogeneous genetic associations of the T2DM susceptibility with the CDKAL1 and HHEX genes by gender.

Genetic dissection of susceptibility to vascular dementia.

Vascular dementia (VD) is the dementia induced by cerebrovascular lesions with a variety of pathophysiological subtypes. Our knowledge of the genetic mechanism of VD was restricted to a few Mendelian forms of VD. The complexity of sporadic VD caused by individual and interactive genetic effects under various environmental exposures renders it difficult to uncover genetic determinants. Much more effort has been made to identify associations of various candidate genes and to explain the variability of the complex VD than the Mendelian VD. The identified genes, however, explain a small portion of the heritability of VD, and the associations are often controversial in different populations. This makes understanding the genetic architecture of VD more complicated. We studied the genes and their sequence variants associated with susceptibility to VD, and many of the genes were involved in lipid metabolism, angiotensin, and inflammation. We also discussed future directions for the association analysis. Endeavors with various approaches would eventually show the genetic architecture of VD and provide a valuable tool in stratifying patients according to their genotypes. This is the first review to introduce a variety of primary studies that may offer some foundation for the genetics of VD.