The association between Adenosine A2A receptor gene polymorphisms and attention deficit hyperactivity disorder in Korean children.

Attention deficit hyperactivity disorder (ADHD) is a common and heritable neurodevelopmental disorder. Particularly, ADHD is known to be related to the dopaminergic system. ADHD symptoms can appear when the dopamine binding affinity diminishes due to dopamine receptor abnormalities, such as the dopamine D2 receptor (D2R). This receptor interacts with the adenosine A2A receptor (A2AR). The A2AR acts as an antagonist of D2R, that is, the increased binding of adenosine with A2AR inhibits the D2R activity. Furthermore, it is found that the single nucleotide polymorphisms of the adenosine A2A receptor gene (ADORA2A) revealed a significant relationship with ADHD in various populations. Therefore, we examined the genetic relationship between ADORA2A polymorphisms (rs2297838, rs5751876, and rs4822492) and Korean ADHD children. A case-control study was performed for 150 cases and 322 controls. Genotyping of ADORA2A polymorphisms was conducted by PCR-RFLP. The results demonstrated that the rs5751876 TC genotype was associated with children with ADHD (p = 0.018). The rs2298383 CC genotype was significantly associated with children with ADHD/HI (p = 0.026). However, when Bonferroni correction was used, the significance vanished (padjusted = 0.054 and padjusted = 0.078, respectively). Haplotype analysis showed that TTC, TCC, and CTG demonstrated a significant difference between ADHD/C children and control groups (padjusted = 0.006, padjusted = 0.011, and padjusted = 0.028, respectively). In conclusion, we propose a possible association between ADORA2A polymorphisms with Korean children having ADHD.

Folate metabolizing gene polymorphisms and genetic vulnerability to preterm birth in Korean women.

BACKGROUND: The folate metabolism that converts homocysteine to methionine is closely related to the accumulation of homocysteine. Increased homocysteine levels lead to an impaired antithrombotic function of the vascular endothelium and uterine-placental circulation, resulting in abnormal pregnancy outcomes. Previous studies have reported that gene polymorphisms in folate metabolism are associated with the development of preterm birth (PTB) in various populations. OBJECTIVE: we performed a case-control study to evaluate the association between five polymorphisms in folate metabolic genes (MTHFR, MTR, MTRR, TCN2) and PTB. METHODS: In this study, a total of 254 subjects were analyzed (111 patients with PTB and 143 women at ≥ 38 weeks of gestation). Genotype and allele frequency differences between patients and control groups and the Hardy-Weinberg equilibrium were assessed using a Chi-square test. For evaluation indicators, odds ratios (ORs) of 95% confidence intervals (CI) were estimated. In addition, we analyzed the combined genotype frequencies of SNPs of folate-metabolizing genes to measure gene-gene interactions for PTB. RESULTS: Our results showed that the MTR rs1805087 GG (p = 0.031), and TCN2 rs1801198 CG genotype (OR 0.53, 95% CI 0.288-0.980, p = 0.042) were significantly associated with PTB. The MTHFR rs4846049 AA showed a marginal trend toward significance (OR 0.15, 95% CI 0.018-1.205, p = 0.041). In particular, the combined genotypes, including MTHFR rs1537514 CC-MTRR rs1801394 GG, MTHFR rs1537514 CC-TCN2 rs1801198 CG, and MTR rs1805087 AA-TCN2 rs1801198 CG, have significant interactions with PTB (OR 0.49, 95% CI 0.248-0.992, p < 0.05). CONCLUSION: The polymorphisms of folate metabolic genes may have a genetic association with the development of PTB in Korean women. A larger sample set and functional studies are required to further elucidate our findings.

Association between the IL-6, IL-10, and TNFα gene polymorphisms and preterm-birth in Korean women.

BACKGROUND: Preterm birth (PTB) is a major adverse pregnancy outcome and largely contributes to increasing neonatal and maternal mortality. Genetic and environmental factors may play an important role in the development of PTB. Numerous studies have shown that immune genes related to the immune system, such as IL-6, IL-10, and TNFα, are associated with the occurrence of PTB. OBJECTIVE: We examined genetic associations between IL-6 rs1800796, IL-10 rs1800872, and TNFα rs1800630 polymorphisms and PTB in Korean women. METHODS: In this study, 115 PTB patients and 147 controls were analyzed. The genotyping of three SNPs was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: Our result showed that the rs1800872 polymorphism was significantly associated with the development of PTB in genotype frequency (odds ratio (OR) 1.71, 95% confidence interval (CI) 1.01-2.90, p = 0.046). We also found a significant association in an analysis of combined genotypes (rs1800796 CC, rs1800872 CA, and rs1800630 CA) (OR 7.43, 95% CI 2.06-26.84, p = 0.001). In a correlation analysis, rs1800630 A allele was significantly related with the increased birth weight (g) within PTB patients (p = 0.005). CONCLUSION: Our results imply possible relationships between the rs1800796, rs1800872, and rs1800630 polymorphisms and the development of PTB.

Association of glutathione S-transferase M1 and T1 null/present polymorphism with physical performance in the Korean population.

Human physical performance is a highly complex phenotype that is influenced by various factors. In particular, genetic factors related to muscle fiber type, bone density, muscle performance, and metabolic processes are known to contribute in varying degrees to athlete status and physical performance in various ethnic groups. To investigate the relationship between these genetic factors and physical performances, we genotyped five genetic polymorphisms (ACE Ins/Del, ACTN3 R577X, ER-α C/T, GSTM1 null/present, and GSTT1 null/present) in 111 Korean athletes and 145 controls. We examined genotype and allele frequency differences between athletes and control groups, along with the odds ratios, using Chi square. One-way analysis of variance (ANOVA) was used to test the significance of differences in continuous variables between the multiple genetic polymorphisms and physical performance test results. The GSTM1 polymorphism exhibited a highly significant association in athletes (p = 0.017). Combined analysis of GSTM1 and GSTT1 also revealed significant differences between athletes and controls (p < 0.05). In the analysis of physical performance within athletes, the ER-α gene polymorphism was associated with the sargent jump and the side-step (p < 0.05), and the GSTM1 gene polymorphism was significantly associated with the 20 m shuttle run and sit-up (p < 0.05). Thus, our data imply that GSTM1 and ER-α gene polymorphisms were associated with physical performance in Korean athletes, although functional studies with larger sample sizes are necessary to elaborate upon these findings.

Mitochondrial DNA haplogroup analysis reveals no association between the common genetic lineages and prostate cancer in the Korean population.

Mitochondrial DNA (mtDNA) variation has recently been suggested to have an association with various cancers, including prostate cancer risk, in human populations. Since mtDNA is haploid and lacks recombination, specific mutations in the mtDNA genome associated with human diseases arise and remain in particular genetic backgrounds referred to as haplogroups. To assess the possible contribution of mtDNA haplogroup-specific mutations to the occurrence of prostate cancer, we have therefore performed a population-based study of a prostate cancer cases and corresponding controls from the Korean population. No statistically significant difference in the distribution of mtDNA haplogroup frequencies was observed between the case and control groups of Koreans. Thus, our data imply that specific mtDNA mutations/lineages did not appear to have a significant effect on a predisposition to prostate cancer in the Korean population, although larger sample sizes are necessary to validate our results.

Lack of association between Y-chromosomal haplogroups and prostate cancer in the Korean population.

The Y chromosome has recently been suggested to have an association with prostate cancer risk in human populations. Since this chromosome is haploid and lacks recombination over most of its length, haplotypes constructed from binary markers throughout the chromosome can be used for association studies. To assess the possible Y-chromosomal contribution to prostate cancer risk, we have therefore analyzed 14 Y-chromosomal binary markers in 106 prostate cancer cases and 110 controls from the Korean population. In contrast to previous findings in the Japanese population, no statistically significant difference in the distribution of Y-chromosomal haplogroup frequencies was observed between the case and control groups of Koreans. Thus, our data imply that the previously reported associations between Y-chromosomal lineages and a predisposition to, or protection against, prostate cancer might be explained by statistical fluctuations, or by genetic effects that are seen only in some environments.