Angiotensin-converting enzyme gene polymorphism in north Indian population with obstructive sleep apnea

Cardiovascular diseases and sleep disorders in South Asians: A scoping review

BACKGROUND

South Asians comprise 20% of the world population. There is a high prevalence of cardiovascular diseases among South Asians, and sleep disorders may be a key risk factor.

OBJECTIVE

The review examined literature about cardiovascular and sleep disorders in South Asian countries and in the United States, United Kingdom, Canada, and the Netherlands.

METHODS

Methods from Arksey and O'Malley's framework and Peter et al. were used to synthesize findings from 23 research studies.

RESULTS

The studies addressed sleep disorders with hypertension, heart failure, diabetes, and obesity. Obstructive sleep apnea and short sleep duration were common and associated with cardiovascular morbidity and mortality at early ages in South Asians. Researchers analyzed polysomnography-derived sleep measures, vascular functions, polymorphisms, C-reactive protein levels, public knowledge about cardiovascular health, and sleep-related questionnaire scores. Most studies were conducted in major metropolitan areas; no data were available about people living in locations with limited health care resources. Among migrant South Asians, researchers did not explore the role of acculturation on sleep patterns and cardiovascular outcomes.

CONCLUSIONS

The review highlights important considerations for researchers who plan to investigate cardiovascular conditions in South Asian communities. There is a need for more knowledge about sleep-related risk factors, and researchers should also examine cultural, political, and socioeconomic factors that affect health care access. This knowledge will be imperative for designing effective and tailored disease prevention strategies for South Asian populations.

Variants of candidate genes associated with the risk of obstructive sleep apnea

BACKGROUND

The researches on the associations between different candidate genes and obstructive sleep apnea (OSA) are inconsistent. Here, we performed a comprehensive qualitative and quantitative analysis to estimate the contribution of variants from candidate genes to the risk of OSA.

METHODS

Qualitative analysis was conducted to find the relationships for all included genes. Then, quantitative analysis of both allele models and genotype models was applied to evaluate the risk variants for OSA. Furthermore, a similar analysis was performed in different ethnic groups.

RESULTS

We included 152 publications containing 75 genes for qualitative analysis. Among them, we included 93 articles containing 28 variants from 16 genes for quantitative analysis. Through allele models, we found 10 risk variants for OSA (rs1801133 of MTHFR, ɛ4 of ApoE, -1438G/A of 5-HT2A, -308G/A of TNF-α, Pro1019Pro of LEPR, rs1130864 and rs2794521 of CRP, D/I of ACE, LPR and VNTR of 5-HTT) with the ORs of 1.21-2.07 in global population. We found that the variant of ɛ2 of ApoE could uniquely decrease the risk of OSA in the East Asian subgroup, while the other 6 variants, including ɛ4 in ApoE, -308G/A in TNF-α, Pro1019Pro in LEPR, D/I in ACE, LPR and VNTR in 5-HTT, could increase the risk of OSA. As for the European subpopulation, we only found that -308G/A in TNF-α could increase the risk for OSA.

CONCLUSIONS

Eleven variants from the candidate genes are associated with the risk of OSA, which also show ethnicity differences in East Asian and European subgroups.

Caveolin-1 polymorphisms in patients with severe obstructive sleep apnea

OBJECTIVE

To investigate the associations of G14713A and T29107A polymorphic variants of Caveolin-1 with severe obstructive sleep apnea (OSA).

MATERIALS AND METHODS

This study was performed on 86 severe OSA patients and 86 controls. Genotyping was performed to investigate the association of G14713A and T29107A polymorphisms of Caveolin-1 with severe OSA.

RESULTS

The distribution of genotypes of T29107A was significantly different between controls and OSA patients with a higher proportion of TT carriers in the OSA group.

CONCLUSION

T29107A-specific genotype of Caveolin-1 may be linked with severe OSA pathogenesis.

Genetically-reduced serum ACE activity might be a causal risk factor for obstructive sleep apnea syndrome: A meta-analysis

We meta-analytically summarized the associations of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism with ACE activity and obstructive sleep apnea syndrome (OSAS) to see whether ACE activity is causally associated with OSAS. Literature search and data abstraction were done in duplicate. Sixteen articles including 2060 OSAS patients and 1878 controls were summarized. Overall, no significance was observed for the association of I/D polymorphism with OSAS, whereas carriers of II genotype (weighted mean difference or WMD, 95% confidence interval or CI, P: −11.976, −17.168 to −6.783, <0.001) or I allele (−9.842, −14.766 to −4.918, <0.001) had a lower level of serum ACE activity compared with DD genotype carriers, respectively. In subgroup analyses, carriers of II genotype were 3.806 times more likely to develop OSAS (95% CI, P: 1.865 to 7.765, <0.001) in OSAS patients with hypertension, without heterogeneity. Mendelian randomization analysis indicated there was 37.4% (95% CI: 1.115 to 3.142) and 32.4% (1.106 to 2.845) increased risk of OSAS by a reduction of 1 U/L in ACE activity for the II genotype and I allele carriers versus DD genotype carriers, respectively. There was no observable publication bias. Collectively, genetically-reduced serum ACE activity might be a causal risk factor for OSAS.

Functional polymorphisms in the promoter region of MMP-2 and MMP-9 and susceptibility to obstructive sleep apnea

Genetic susceptibility to obstructive sleep apnea (OSA) has been a research focus in the scientific community in the past few years. In this study, we recruited 375 subjects to investigate whether functional polymorphisms in the promoter region of matrix metalloproteinase (MMP)-2 (-1306C/T) and MMP-9 (-1562C/T) increased susceptibility to OSA. Our study showed no significant association between MMP-2 -1306C/T polymorphism and risk of OSA (T vs. C: OR = 1.01, 95% CI = 0.67-1.52; P = 0.97). Compared with the MMP-9 -1562C allele, the -1562T allele was associated with increased risk of OSA (T vs. C: OR = 1.56, 95% CI = 1.02-2.39; P = 0.04). However, neither MMP-2 -1306C/T nor MMP-9 -1562C/T polymorphism was found to be associated with severity of the disease. Our study suggested that the MMP-2 -1306C/T polymorphism was not associated with OSA susceptibility, whereas the MMP-9 -1562T allele was associated with increased risk of OSA.

Leptin and leptin receptor gene polymorphisms in obstructive sleep apnea: a HuGE review and meta-analysis

BACKGROUND

Several epidemiological studies have been conducted to examine the association between leptin and leptin receptor (LEPR) gene polymorphisms and risk of obstructive sleep apnea (OSA). However, the results remain conflicting rather than conclusive.

OBJECTIVE

The aim of this study was to investigate associations of leptin and LEPR polymorphisms and risk of OSA.

METHODS

We carried out a search in MEDLINE, EMBASE, and Chinese National Knowledge Infrastructure (CNKI) databases for relevant studies. Data were extracted using a standardized form and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of the association.

RESULTS

Overall, no statistically significant association of OSA risk and polymorphisms of Gln233Arg, Lys109Arg, Lys656Asn, 19A/G, Pro1019Arg, and 2548G/A was found. However, in the stratified analysis by ethnicity, Gln233Arg polymorphism was associated with a significantly decreased risk of OSA in European (homozygote comparison: OR = 0.35, 95% CI = 0.14-0.85, P = 0.02), but not for Asian population.

CONCLUSIONS

Our study suggested that leptin and LEPR polymorphisms had no association with OSA risk in all examined patients, whereas there was an association between Gln233Arg polymorphism and OSA risk in Europeans.

Vascular endothelial growth factor genotypes and haplotypes contribute to the susceptibility of obstructive sleep apnea syndrome

Background

To investigate whether VEGF polymorphisms (-460T/C, +405G/C, and +936C/T)/haplotypes influence the susceptibility of obstructive sleep apnea (OSA).

Method

A prospective case-control study was conducted to evaluate the genetic effects of VEGF polymorphisms on the development of OSA. 150 patients and 225 healthy controls were recruited for this study and their genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). The odds ratios (OR) and 95% confidence intervals (CI) were calculated by logistic regression analysis.

Result

Our study showed that the -460C allele (C vs. T: OR = 1.95, 95% CI = 1.38–2.76) and +936T allele (T vs. C: OR = 1.48, 95% CI = 1.02–2.15) were associated with an increased OSA risk, whereas +405C allele was associated with a decreased susceptibility to OSA (C vs. G: OR = 0.61, 95% CI = 0.45–0.83). Compared with the most common haplotype CCT, CGC (OR = 2.22, 95% CI = 1.19–4.13) and TGC (OR = 3.83, 95% CI = 1.56–9.40) were associated with a significantly increased risk of OSA.

Conclusion

These observations implied that VEGF gene polymorphisms might be associated with the susceptibility to OSA. These results need to be validated by other independent studies, especially in diverse ethnic populations.

A functional EGF+61 polymorphism is associated with severity of obstructive sleep apnea

BACKGROUND

Involvement of epidermal growth factor (EGF) is reported in diseases caused by hypoxia. Its functional polymorphism may alter its transcription, affecting EGF expression, contributing to obstructive sleep apnea (OSA).

OBJECTIVE

The aim of this study was to investigate associations of EGF+61 polymorphism and risk of OSA.

METHODS

Two hundred two participants were enrolled in this case-control study. DNA was extracted from peripheral blood, and EGF 61A/G polymorphism was determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay.

RESULTS

No significant association between EGF 61 A/G polymorphism and risk of OSA was observed in any of the gene models tested (AA vs. GG: OR = 0.97, 95% CI = 0.37-2.55; P = 0.95). However, compared with GG genotype, AG genotype associated with decreased risk of severe OSA (AG vs. GG: OR = 0.32, 95% CI = 0.11-0.94).

CONCLUSIONS

Our study showed that AG genotype has a protective effect on OSA patients against severe disease, although EGF 61A/G polymorphisms have no role on the risk of the disease. Additional large studies should further validate our findings.

Association of ACE I/D polymorphism with obstructive sleep apnea susceptibility: evidence based on 2,228 subjects

BACKGROUND

Whether the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene increases susceptibility to obstructive sleep apnea (OSA) is controversial and still undetermined. Therefore, this meta-analysis was performed to systematically assess the possible association between them.

METHODS

The OVID, Medline, Embase, Web of Science, CNKI, and Wangfang databases were searched to identify eligible studies focusing on the association between ACE polymorphism I/D and susceptibility to OSA.

RESULTS

A total of 2,228 subjects from nine studies were subjected to meta-analysis. Overall, ACE polymorphism I/D had no statistically significant association with increased OSA risk under all genetic models (P > 0.05). In the subgroup analysis by ethnicity or study design, still no significant associations were found for all genetic models (P > 0.05). However, ACE polymorphism I/D was significantly associated with susceptibility to OSA with hypertension in Asians under heterozygous comparison and dominant model. The ID genotype carriers and D allele carriers (ID + DD) were about 53% less likely (odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.29-0.74; P = 0.001) and about 52% less likely (OR = 0.48, 95% CI = 0.24-0.99; P = 0.047), respectively, to have OSA with hypertension compared to carriers of the II genotype.

CONCLUSIONS

ACE polymorphism I/D had no statistically significant association with increased OSA risk, but the II genotype of ACE may be a risk factor for OSA with hypertension in Asians. OSA cases who develop hypertension may derive from a different mechanism compared to essential hypertension. Studies with large sample size and representative population are warranted to verify this finding.

Polymorphisms in nitric oxide synthase and endothelin genes among children with obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is associated with adverse and interdependent cognitive and cardiovascular consequences. Increasing evidence suggests that nitric oxide synthase (NOS) and endothelin family (EDN) genes underlie mechanistic aspects of OSA-associated morbidities. We aimed to identify single nucleotide polymorphisms (SNPs) in the NOS family (3 isoforms), and EDN family (3 isoforms) to identify potential associations of these SNPs in children with OSA.

Methods

A pediatric community cohort (ages 5–10 years) enriched for snoring underwent overnight polysomnographic (NPSG) and a fasting morning blood draw. The diagnostic criteria for OSA were an obstructive apnea-hypopnea Index (AHI) >2/h total sleep time (TST), snoring during the night, and a nadir oxyhemoglobin saturation <92%. Control children were defined as non-snoring children with AHI <2/h TST (NOSA). Endothelial function was assessed using a modified post-occlusive hyperemic test. The time to peak reperfusion (Tmax) was considered as the indicator for normal endothelial function (NEF; Tmax<45 sec), or ED (Tmax≥45 sec). Genomic DNA from peripheral blood was extracted and allelic frequencies were assessed for, NOS1 (209 SNPs), NOS2 (122 SNPs), NOS3 (50 SNPs), EDN1 (43 SNPs), EDN2 (48 SNPs), EDN3 (14 SNPs), endothelin receptor A, EDNRA, (27 SNPs), and endothelin receptor B, EDNRB (23 SNPs) using a custom SNPs array. The relative frequencies of NOS-1,-2, and −3, and EDN-1,-2,-3,-EDNRA, and-EDNRB genotypes were evaluated in 608 subjects [128 with OSA, and 480 without OSA (NOSA)]. Furthermore, subjects with OSA were divided into 2 subgroups: OSA with normal endothelial function (OSA-NEF), and OSA with endothelial dysfunction (OSA-ED). Linkage disequilibrium was analyzed using Haploview version 4.2 software.

Results

For NOSA vs. OSA groups, 15 differentially distributed SNPs for NOS1 gene, and 1 SNP for NOS3 emerged, while 4 SNPs for EDN1 and 1 SNP for both EDN2 and EDN3 were identified. However, in the smaller sub-group for whom endothelial function was available, none of the significant SNPs was retained due to lack of statistical power.

Conclusions

Differences in the distribution of polymorphisms among NOS and EDN gene families suggest that these SNPs could play a contributory role in the pathophysiology and risk of OSA-induced cardiovascular morbidity. Thus, analysis of genotype-phenotype interactions in children with OSA may assist in the formulation of categorical risk estimates.