Adherence to a healthy sleep pattern and new-onset acute kidney injury

OBJECTIVES

To investigate the prospective association of individual sleep characteristics and a healthy sleep pattern with new-onset acute kidney injury in general population.

METHODS

The UK Biobank enrolled over 500,000 participants, aged 37-73years, across the UK from 2006 to 2010. Of these, 375,216 participants were included in the current study. A healthy sleep score, ranging from 0 to 5 points, was created by combining five major sleep characteristics, including sleep duration, chronotype, insomnia, snoring, and daytime sleepiness. New-onset acute kidney injury was defined by ICD-10 code N17, ascertained by primary care data, hospital inpatient data, death register records, or self-reported medical conditions.

RESULTS

During a median follow-up period of 12.0years, 14,492 (3.9%) participants developed acute kidney injury. Overall, the healthy sleep score was significantly inversely associated with the risk of new-onset acute kidney injury (per 1-point increment; hazards ratio, 0.95; 95%CI, 0.93-0.97), especially in nondiabetes (hazards ratio, 0.94; 95%CI, 0.92-0.96; vs. diabetes, hazards ratio, 1.01; 95%CI, 0.96-1.05; P-interaction=.008). The genetic predisposition of estimated glomerular filtration rate and acute kidney injury did not significantly modify the association between the healthy sleep score and acute kidney injury (both P-interactions >.05). Sleep 7-8 hours per day (vs. <7 hours or ≥9 hours; hazards ratio, 0.92; 95%CI, 0.88-0.96), early chronotype (vs. evening chronotype; hazards ratio, 0.93; 95%CI, 0.89-0.97), never or rarely insomnia (vs. sometimes/usually insomnia; hazards ratio, 0.93; 95%CI, 0.88-0.97) and no frequent daytime sleepiness (vs. often/always daytime sleepiness; hazards ratio, 0.90; 95%CI, 0.81-0.99) were significantly associated with a lower risk of new-onset acute kidney injury.

CONCLUSIONS

A healthy sleep pattern was significantly associated with a lower risk of new-onset acute kidney injury, regardless of the genetic risks.

Genetic risk scores: are they important for diabetes management? results from multiple cross-sectional studies

BACKGROUND

Several genetic risk scores (GRS) for type 2 diabetes (T2DM) have been published, but not replicated. We aimed to 1) replicate previous findings on the association between GRS on prevalence of T2DM and 2) assess the association between GRS and T2DM management in a sample of community-dwelling people from Switzerland.

METHODS

Four waves from a prospective study conducted in Lausanne. Seven GRS related to T2DM were selected, and compared between participants with and without T2DM, and between controlled and uncontrolled participants treated for T2DM.

RESULTS

Data from 5426, 4017, 2873 and 2170 participants from the baseline, first, second and third follow-ups, respectively, was used. In all study periods, participants with T2DM scored higher than participants without T2DM in six out of seven GRS. Data from 367, 437, 285 and 207 participants with T2DM was used. In all study periods, approximately half of participants treated for T2DM did not achieve adequate fasting blood glucose or HbA1c levels, and no difference between controlled and uncontrolled participants was found for all seven GRS. Power analyses showed that most GRS needed a sample size above 1000 to consider the difference between controlled and uncontrolled participants as statistically significant at p = 0.05.

CONCLUSION

In this study, we confirmed the association between most published GRS and diabetes. Conversely, no consistent association between GRS and diabetes control was found. Use of GRS to manage patients with T2DM in clinical practice is not justified.

Genetic variation and elevated liver enzymes during childhood, adolescence and early adulthood

BACKGROUND

Genetic factors influence the risk of fatty liver disease (FLD) in adults. The aim of this study was to test if, and when, genetic risk factors known to affect FLD in adults begin to exert their deleterious effects during childhood, adolescence and early adulthood.

METHODS

We included up to 4018 British children and adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Three genetic variants known to associate robustly with FLD in adults (PNPLA3 rs738409, TM6SF2 rs58542926 and HSD17B13 rs72613567) were tested for association with plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST) during childhood (mean age: 9.9 years), early adolescence (15.5 years), late adolescence (17.8 years), and early adulthood (24.5 years). We also tested the associations of a 17-variant score and whole-genome polygenic risk scores (PRS) derived from associations in adults with plasma ALT and AST at the same four time points. Associations with elastography-derived liver steatosis and fibrosis were tested in early adulthood.

RESULTS

Genetic risk factors for FLD (individually, combined into a 3-variant score, a 17-variant score and as a genome-wide PRS), were associated with higher liver enzymes, beginning in childhood and throughout adolescence and early adulthood. The ALT-increasing effects of the genetic risk variants became larger with increasing age. The ALT-PRS was associated with liver steatosis in early adulthood. No genetic associations with fibrosis were observed.

CONCLUSIONS

Genetic factors that promote FLD in adults associate with elevated liver enzymes already during childhood, and their effects get amplified with increasing age.

Identifying shared genetic architecture between rheumatoid arthritis and other conditions: a phenome-wide association study with genetic risk scores

BACKGROUND

Rheumatoid arthritis (RA) shares genetic variants with other autoimmune conditions, but existing studies test the association between RA variants with a pre-defined set of phenotypes. The objective of this study was to perform a large-scale, systemic screen to determine phenotypes that share genetic architecture with RA to inform our understanding of shared pathways.

METHODS

In the UK Biobank (UKB), we constructed RA genetic risk scores (GRS) incorporating human leukocyte antigen (HLA) and non-HLA risk alleles. Phenotypes were defined using groupings of International Classification of Diseases (ICD) codes. Patients with an RA code were excluded to mitigate the possibility of associations being driven by the diagnosis or management of RA. We performed a phenome-wide association study, testing the association between the RA GRS with phenotypes using multivariate generalized estimating equations that adjusted for age, sex, and first five principal components. Statistical significance was defined using Bonferroni correction. Results were replicated in an independent cohort and replicated phenotypes were validated using medical record review of patients.

FINDINGS

We studied n = 316,166 subjects from UKB without evidence of RA and screened for association between the RA GRS and n = 1317 phenotypes. In the UKB, 20 phenotypes were significantly associated with the RA GRS, of which 13 (65%) were immune mediated conditions including polymyalgia rheumatica, granulomatosis with polyangiitis (GPA), type 1 diabetes, and multiple sclerosis. We further identified a novel association in Celiac disease where the HLA and non-HLA alleles had strong associations in opposite directions. Strikingly, we observed that the non-HLA GRS was exclusively associated with greater risk of the validated conditions, suggesting shared underlying pathways outside the HLA region.

INTERPRETATION

This study replicated and identified novel autoimmune phenotypes verified by medical record review that share immune pathways with RA and may inform opportunities for shared treatment targets, as well as risk assessment for conditions with a paucity of genomic data, such as GPA.

FUNDING

This research was funded by the US National Institutes of Health (P30AR072577, R21AR078339, R35GM142879, T32AR007530) and the Harold and DuVal Bowen Fund.

Assessment of multi-population polygenic risk scores for lipid traits in African Americans

Polygenic risk scores (PRS) based on genome-wide discoveries are promising predictors or classifiers of disease development, severity, and/or progression for common clinical outcomes. A major limitation of most risk scores is the paucity of genome-wide discoveries in diverse populations, prompting an emphasis to generate these needed data for trans-population and population-specific PRS construction. Given diverse genome-wide discoveries are just now being completed, there has been little opportunity for PRS to be evaluated in diverse populations independent from the discovery efforts. To fill this gap, we leverage here summary data from a recent genome-wide discovery study of lipid traits (HDL-C, LDL-C, triglycerides, and total cholesterol) conducted in diverse populations represented by African Americans, Hispanics, Asians, Native Hawaiians, Native Americans, and others by the Population Architecture using Genomics and Epidemiology (PAGE) Study. We constructed lipid trait PRS using PAGE Study published genetic variants and weights in an independent African American adult patient population linked to de-identified electronic health records and genotypes from the Illumina Metabochip (n = 3,254). Using multi-population lipid trait PRS, we assessed levels of association for their respective lipid traits, clinical outcomes (cardiovascular disease and type 2 diabetes), and common clinical labs. While none of the multi-population PRS were strongly associated with the tested trait or outcome, PRS_LDL-Cwas nominally associated with cardiovascular disease. These data demonstrate the complexity in applying PRS to real-world clinical data even when data from multiple populations are available.

Integrating oculomics with genomics reveals imaging biomarkers for preventive and personalized prediction of arterial aneurysms

Objective

Arterial aneurysms are life-threatening but usually asymptomatic before requiring hospitalization. Oculomics of retinal vascular features (RVFs) extracted from retinal fundus images can reflect systemic vascular properties and therefore were hypothesized to provide valuable information on detecting the risk of aneurysms. By integrating oculomics with genomics, this study aimed to (i) identify predictive RVFs as imaging biomarkers for aneurysms and (ii) evaluate the value of these RVFs in supporting early detection of aneurysms in the context of predictive, preventive and personalized medicine (PPPM).

Methods

This study involved 51,597 UK Biobank participants who had retinal images available to extract oculomics of RVFs. Phenome-wide association analyses (PheWASs) were conducted to identify RVFs associated with the genetic risks of the main types of aneurysms, including abdominal aortic aneurysm (AAA), thoracic aneurysm (TAA), intracranial aneurysm (ICA) and Marfan syndrome (MFS). An aneurysm-RVF model was then developed to predict future aneurysms. The performance of the model was assessed in both derivation and validation cohorts and was compared with other models employing clinical risk factors. An RVF risk score was derived from our aneurysm-RVF model to identify patients with an increased risk of aneurysms.

Results

PheWAS identified a total of 32 RVFs that were significantly associated with the genetic risks of aneurysms. Of these, the number of vessels in the optic disc ('ntreeA') was associated with both AAA (β = -0.36, P = 6.75e-10) and ICA (β = -0.11, P = 5.51e-06). In addition, the mean angles between each artery branch ('curveangle_mean_a') were commonly associated with 4 MFS genes (FBN1: β = -0.10, P = 1.63e-12; COL16A1: β = -0.07, P = 3.14e-09; LOC105373592: β = -0.06, P = 1.89e-05; C8orf81/LOC441376: β = 0.07, P = 1.02e-05). The developed aneurysm-RVF model showed good discrimination ability in predicting the risks of aneurysms. In the derivation cohort, the C-index of the aneurysm-RVF model was 0.809 [95% CI: 0.780-0.838], which was similar to the clinical risk model (0.806 [0.778-0.834]) but higher than the baseline model (0.739 [0.733-0.746]). Similar performance was observed in the validation cohort, with a C-index of 0.798 (0.727-0.869) for the aneurysm-RVF model, 0.795 (0.718-0.871) for the clinical risk model and 0.719 (0.620-0.816) for the baseline model. An aneurysm risk score was derived from the aneurysm-RVF model for each study participant. The individuals in the upper tertile of the aneurysm risk score had a significantly higher risk of aneurysm compared to those in the lower tertile (hazard ratio = 17.8 [6.5-48.8], P = 1.02e-05).

Conclusion

We identified a significant association between certain RVFs and the risk of aneurysms and revealed the impressive capability of using RVFs to predict the future risk of aneurysms by a PPPM approach. Our finds have great potential to support not only the predictive diagnosis of aneurysms but also a preventive and more personalized screening plan which may benefit both patients and the healthcare system.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00315-7.

Association of CELSR2, APOB100, ABCG5/8, LDLR, and APOE polymorphisms and their genetic risks with lipids among the Thai subjects

Background

Hypercholesterolemia is a common cardiovascular risk factor. The aim of this study was to investigate the association of CELSR2 (rs629301), APOB100 (rs1367117), ABCG5/8 (rs6544713), LDLR (rs6511720), and APOE (rs429358, rs7412) polymorphisms, and their genetic risk scores with lipids among Thai subjects.

Methods

A total of 459 study subjects (184 males, and 275 females) were enrolled. Blood pressure, serum lipids, and fasting blood sugar were measured. CELSR2 (rs629301), APOB100 (rs1367117), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms were analyzed using PCR-HRM. APOE (rs429358, rs7412) polymorphism was analyzed using PCR-RFLP.

Results

Total cholesterol (TC) levels were significantly higher in APOB100 AA genotype compared with GG, or AA + AG genotypes in total subjects. In addition, significantly higher concentrations of TC and low density lipoprotein cholesterol (LDL-C) were observed in APOE4 carriers compared to APOE2 carriers in total subjects, males, and females. The significantly higher concentrations of TC were observed in APOE4 carriers compared to APOE3 carriers in females. Moreover, the concentrations of TC, and LDL-C were significantly increased with genetic risk scores of APOB100, and APOE polymorphisms in total subjects, and females. There was no association between CELSR2 (rs629301), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms and serum lipids.

Conclusion

APOB100 (rs1367117), and APOE (rs429358, rs7412) but not CELSR2 (rs629301), ABCG5/8 (rs6544713), and LDLR (rs6511720) polymorphisms were associated with serum lipids. The cumulative risk alleles of APOB100 (rs1367117), and APOE (rs429358, rs7412) polymorphisms could enhance the elevated concentrations of TC, and LDL-C, and they may be used to predict severity of hypercholesterolemia among Thai subjects.

Associations of habitual glucosamine supplementation with incident gout: a large population based cohort study

OBJECTIVES

The association between habitual glucosamine use and incident gout has not been examined in previous studies. We aimed to evaluate the association of habitual use of glucosamine with the risk of gout in general population.

METHODS

A total of 436,594 participants (55.4% female) without prior gout at baseline who completed a questionnaire on supplementation use, which included glucosamine, in the UK Biobank were enrolled. Incident gout was recorded from self-report, death register, primary care, and hospital admission data.

RESULTS

At baseline, 53,433 (22.1%) females and 30,685 (15.8%) males reported habitual glucosamine use. During a median follow-up period of 12.1 years, 1718 (0.7%) females and 5685 (2.9%) males developed gout. After multivariable adjustment for major risk factors, glucosamine use was associated with a significantly lower risk of incident gout in females (hazard ratio [HR], 0.81, 95% confidence interval [CI], 0.71-0.92), but not in males (HR, 1.05, 95% CI, 0.97-1.13), compared with non-use (P-interaction &lt; 0.001). Among females, the inverse association between glucosamine use and gout was stronger in participants with diuretics use (HR, 0.64, 95% CI, 0.50-0.81) than those without diuretics use (HR, 0.89, 95% CI, 0.77-1.03) (P-interaction = 0.015). Moreover, gout genetic risk scores did not significantly modify the association between glucosamine use and the risk of incident gout in males (P-interaction = 0.548) or females (P-interaction = 0.183).

CONCLUSIONS

Habitual glucosamine use to relieve osteoarthritis pain was related to lower risk of gout in females, but not in males.

Predictive Value of Genetic Risk Scores in the Development of Colorectal Adenomas

INTRODUCTION

Unlike colorectal cancer (CRC), few studies have explored the predictive value of genetic risk scores (GRS) in the development of colorectal adenomas (CRA), either alone or in combination with other demographic and clinical factors.

METHODS

In this study, genomic DNA from 613 Spanish Caucasian patients with CRA and 829 polyp-free individuals was genotyped for 88 single-nucleotide polymorphisms (SNPs) associated with CRC risk using the MassArray™ (Sequenom) platform. After applying a multivariate logistic regression model, five SNPs were selected to calculate the GRS. Regression models adjusted by sex, age, family history of CRC, chronic use of NSAIDs, low-dose ASA, and consumption of tobacco were built in order to study the association between GRS and CRA risk. We evaluated the discriminatory capacity using the area under the receiver operating characteristic curve (AUC). The interactions between demographic information and GRS were also analyzed.

RESULTS

Significant associations between high GRS values and risk of CRA for analyzed models were observed. In particular, patients with higher GRS values had 2.3-2.6-fold increase in risk of CRA compared to patients with middle values. Combining sex and age with the GRS significantly increased the discriminatory accuracy of the univariate model with GRS alone. The best model achieved an AUC value of 0.665 (95% CI: 0.63-0.69). The GRS showed a different behavior depending on sex and age.

CONCLUSION

Our findings showed that, besides sex and age, GRS is an important risk factor for development of CRA and may be useful for CRC risk stratification and adaptation of screening programs.

Calculating genetic risk for dysfunction in pleiotropic biological processes using whole exome sequencing data

BACKGROUND

Numerous genes are implicated in autism spectrum disorder (ASD). ASD encompasses a wide-range and severity of symptoms and co-occurring conditions; however, the details of how genetic variation contributes to phenotypic differences are unclear. This creates a challenge for translating genetic evidence into clinically useful knowledge. Sleep disturbances are particularly prevalent co-occurring conditions in ASD, and genetics may inform treatment. Identifying convergent mechanisms with evidence for dysfunction that connect ASD and sleep biology could help identify better treatments for sleep disturbances in these individuals.

METHODS

To identify mechanisms that influence risk for ASD and co-occurring sleep disturbances, we analyzed whole exome sequence data from individuals in the Simons Simplex Collection (n = 2380). We predicted protein damaging variants (PDVs) in genes currently implicated in either ASD or sleep duration in typically developing children. We predicted a network of ASD-related proteins with direct evidence for interaction with sleep duration-related proteins encoded by genes with PDVs. Overrepresentation analyses of Gene Ontology-defined biological processes were conducted on the resulting gene set. We calculated the likelihood of dysfunction in the top overrepresented biological process. We then tested if scores reflecting genetic dysfunction in the process were associated with parent-reported sleep duration.

RESULTS

There were 29 genes with PDVs in the ASD dataset where variation was reported in the literature to be associated with both ASD and sleep duration. A network of 108 proteins encoded by ASD and sleep duration candidate genes with PDVs was identified. The mechanism overrepresented in PDV-containing genes that encode proteins in the interaction network with the most evidence for dysfunction was cerebral cortex development (GO:0,021,987). Scores reflecting dysfunction in this process were associated with sleep durations; the largest effects were observed in adolescents (p = 4.65 × 10^-3).

CONCLUSIONS

Our bioinformatic-driven approach detected a biological process enriched for genes encoding a protein-protein interaction network linking ASD gene products with sleep duration gene products where accumulation of potentially damaging variants in individuals with ASD was associated with sleep duration as reported by the parents. Specifically, genetic dysfunction impacting development of the cerebral cortex may affect sleep by disrupting sleep homeostasis which is evidenced to be regulated by this brain region. Future functional assessments and objective measurements of sleep in adolescents with ASD could provide the basis for more informed treatment of sleep problems in these individuals.

Common genetic variants do not predict recurrent events in coronary heart disease patients

Background

It is unclear whether genetic variants identified from single nucleotide polymorphisms (SNPs) strongly associated with coronary heart disease (CHD) in genome-wide association studies (GWAS), or a genetic risk score (GRS) derived from them, can help stratify risk of recurrent events in patients with CHD.

Methods

Study subjects were enrolled at the close-out of the LIPID randomised controlled trial of pravastatin vs placebo. Entry to the trial had required a history of acute coronary syndrome 3–36 months previously, and patients were in the trial for a mean of 36 months. Patients who consented to a blood sample were genotyped with a custom designed array chip with SNPs chosen from known CHD-associated loci identified in previous GWAS. We evaluated outcomes in these patients over the following 10 years.

Results

Over the 10-year follow-up of the cohort of 4932 patients, 1558 deaths, 898 cardiovascular deaths, 727 CHD deaths and 375 cancer deaths occurred. There were no significant associations between individual SNPs and outcomes before or after adjustment for confounding variables and for multiple testing. A previously validated 27 SNP GRS derived from SNPs with the strongest associations with CHD also did not show any independent association with recurrent major cardiovascular events.

Conclusions

Genetic variants based on individual single nucleotide polymorphisms strongly associated with coronary heart disease in genome wide association studies or an abbreviated genetic risk score derived from them did not help risk profiling in this well-characterised cohort with 10-year follow-up. Other approaches will be needed to incorporate genetic profiling into clinically relevant stratification of long-term risk of recurrent events in CHD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02520-0.

Reporting methodological issues of the mendelian randomization studies in health and medical research: a systematic review

Background

Mendelian randomization (MR) studies using Genetic risk scores (GRS) as an instrumental variable (IV) have increasingly been used to control for unmeasured confounding in observational healthcare databases. However, proper reporting of methodological issues is sparse in these studies. We aimed to review published papers related to MR studies and identify reporting problems.

Methods

We conducted a systematic review using the clinical articles published between 2009 and 2019. We searched PubMed, Scopus, and Embase databases. We retrieved information from every MR study, including the tests performed to evaluate assumptions and the modelling approach used for estimation. Using our inclusion/exclusion criteria, finally, we identified 97 studies to conduct the review according to the PRISMA statement.

Results

Only 66 (68%) of the studies empirically verified the first assumption (Relevance assumption), and 40 (41.2%) studies reported the appropriate tests (e.g., R2, F-test) to investigate the association. A total of 35.1% clearly stated and discussed theoretical justifications for the second and third assumptions. 30.9% of the studies used a two-stage least square, and 11.3% used the Wald estimator method for estimating IV. Also, 44.3% of the studies conducted a sensitivity analysis to illuminate the robustness of estimates for violations of the untestable assumptions.

Conclusions

We found that incompleteness of the justification of the assumptions for the instrumental variable in MR studies was a common problem in our selected studies. This may misdirect the findings of the studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01504-0.

Performance of models to predict hepatocellular carcinoma risk among UK patients with cirrhosis and cured HCV infection

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) prediction models can inform clinical decisions about HCC screening provided their predictions are robust. We conducted an external validation of 6 HCC prediction models for UK patients with cirrhosis and a HCV virological cure.

METHODS

Patients with cirrhosis and cured HCV were identified from the Scotland HCV clinical database (N = 2,139) and the STratified medicine to Optimise Treatment of Hepatitis C Virus (STOP-HCV) study (N = 606). We calculated patient values for 4 competing non-genetic HCC prediction models, plus 2 genetic models (for the STOP-HCV cohort only). Follow-up began at the date of sustained virological response (SVR) achievement. HCC diagnoses were identified through linkage to nation-wide cancer, hospitalisation, and mortality registries. We compared discrimination and calibration measures between prediction models.

RESULTS

Mean follow-up was 3.4-3.9 years, with 118 (Scotland) and 40 (STOP-HCV) incident HCCs observed. The age-male sex-ALBI-platelet count score (aMAP) model showed the best discrimination; for example, the Concordance index (C-index) in the Scottish cohort was 0.77 (95% CI 0.73-0.81). However, for all models, discrimination varied by cohort (being better for the Scottish cohort) and by age (being better for younger patients). In addition, genetic models performed better in patients with HCV genotype 3. The observed 3-year HCC risk was 3.3% (95% CI 2.6-4.2) and 5.1% (3.5-7.0%) in the Scottish and STOP-HCV cohorts, respectively. These were most closely matched by aMAP, in which the mean predicted 3-year risk was 3.6% and 5.0% in the Scottish and STOP-HCV cohorts, respectively.

CONCLUSIONS

aMAP was the best-performing model in terms of both discrimination and calibration and, therefore, should be used as a benchmark for rival models to surpass. This study underlines the opportunity for 'real-world' risk stratification in patients with cirrhosis and cured HCV. However, auxiliary research is needed to help translate an HCC risk prediction into an HCC-screening decision.

LAY SUMMARY

Patients with cirrhosis and cured HCV are at high risk of developing liver cancer, although the risk varies substantially from one patient to the next. Risk calculator tools can alert clinicians to patients at high risk and thereby influence decision-making. In this study, we tested the performance of 6 risk calculators in more than 2,500 patients with cirrhosis and cured HCV. We show that some risk calculators are considerably better than others. Overall, we found that the 'aMAP' calculator worked the best, but more work is needed to convert predictions into clinical decisions.

Association of serum 25-hydroxyvitamin D with metabolic syndrome and type 2 diabetes: a one sample Mendelian randomization study

Background

Vitamin D deficiency has been associated with type 2 diabetes (T2D) and metabolic syndrome (MS) and its components. However, it is unclear whether a low concentration of vitamin D is the cause or consequence of these health conditions. Thus, this study aimed to evaluate the association of vitamin D concentrations and its genetic risk scores (GRSs) with MS and its component diseases, such as T2D, in middle-aged and elderly participants from rural eastern China.

Methods

A subset of 2393 middle-aged and elderly individuals were selected from 70,458 participants of the Nantong Chronic Diseases Study of 2017–2018 in China. We used two 25-hydroxyvitamin D (25[OH]D) synthesis single-nucleotide polymorphisms (SNPs) (DHCR7-rs12785878 and CYP2R1-rs10741657) and two 25(OH) D metabolism SNPs (GC-rs2282679 and CYP24A1-rs6013897) for creating GRSs, which were used as instrumental variables to assess the effect of genetically lowered 25(OH) D concentrations on MS and T2D based on the Wald ratio. F statistics were used to validate that the four SNPs genetically determined 25(OH) D concentrations.

Results

Compared to vitamin D sufficient individuals, individuals with vitamin D insufficiency had an odds ratio (OR [95% confidence interval {CI}]) of MS of 1.30 (1.06–1.61) and of T2D of 1.32 (1.08–1.64), individuals with vitamin D deficiency had an ORs (95% CI) of MS of 1.50 (1.24–1.79) and of T2D of 1.47 (1.12–1.80), and those with vitamin D severe deficiency had an ORs (95% CI) of MS of 1.52 (1.29–1.85) and of T2D of 1.54 (1.27–1.85). Mendelian randomization analysis showed a 25-nmol/L decrease in genetically instrumented serum 25(OH) D concentrations using the two synthesis SNPs (DHCR7 and CYP2R1 genes) associated with the risk of T2D and abnormal diastolic blood pressure (DBP) with ORs of 1.10 (95%CI: 1.02–1.45) for T2D and 1.14 (95%CI: 1.03–1.43) for DBP.

Conclusions

This one sample Mendelian randomization analysis shows genetic evidence for a causal role of lower 25(OH) D concentrations in promoting of T2D and abnormal DBP in middle-aged and elderly participants from rural China.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02307-6.

Exploratory analysis of the genetics of impulse control disorders in Parkinson's disease using genetic risk scores

OBJECTIVE

To study the association between impulse control disorders (ICDs) in Parkinson's disease (PD) and genetic risk scores (GRS) for 40 known or putative risk factors (e.g. depression, personality traits).

BACKGROUND

In absence of published genome-wide association studies (GWAS), little is known about the genetics of ICDs in PD. GRS of related phenotypes, for which large GWAS are available, may help shed light on the genetic contributors of ICDs in PD.

METHODS

We searched for GWAS on European ancestry populations with summary statistics publicly available for a broad range of phenotypes, including other psychiatric disorders, personality traits, and simple phenotypes. We separately tested their predictive ability in two of the largest PD cohorts with clinical and genetic available: the Parkinson's Progression Markers Initiative database (N = 368, 33% female, age range = [33-84]) and the Drug Interaction With Genes in Parkinson's Disease study (N = 373, 40% female, age range = [29-85]).

RESULTS

We considered 40 known or putative risk factors for ICDs in PD for which large GWAS had been published. After Bonferroni correction for multiple comparisons, no GRS or the combination of the 40 GRS were significantly associated with ICDs from the analyses in each cohort separately and from the meta-analysis.

CONCLUSION

Albeit unsuccessful, our approach will gain power in the coming years with increasing availability of genotypes in clinical cohorts of PD, but also from future increase in GWAS sample sizes of the phenotypes we considered. Our approach may be applied to other complex disorders, for which GWAS are not available or limited.

Comparison of risk allele frequencies of single nucleotide polymorphisms associated with age-related macular degeneration in different ethnic groups

BACKGROUND

The prevalence of age-related macular degeneration (AMD) varies from 6.8 to 18.3% for all forms of AMD and from 0.6 to 2.6% for late AMD according to race, suggesting the existence of genetic differences among races. The purpose of this study was to determine the genetic causes of differences in the prevalence of AMD among individuals of different races.

METHODS

We collected 138 AMD-associated single nucleotide polymorphisms (SNPs) from a genome-wide association studies catalog. Their population-level allele frequencies were derived based on the 1000 Genomes Project and Korean Reference Genome Database. We used Fisher's exact tests to assess whether the effect allele at a given SNP was significantly enriched or depleted in the database.

RESULTS

European, American, and South Asian populations showed similar heatmap patterns, whereas East Asian, and Korean populations had distinct patterns. Korean populations exhibited patterns that were different from those of the other groups; rs5754227 (SYN3), rs1626340 (TGFBR1/COL15A1), rs3750846(ARMS2/HTRA1), and rs9564692 (B3GALTL) were enriched, whereas rs2230199 (C3) and rs73036519 (EXOC3L2/MARK4) were depleted in Koreans; these SNPs are associated with late AMD. The genetic risk score calculated from allele frequencies was not less in East Asians than in Europeans.

CONCLUSION

The prevalence of AMD is lower in Asians than in Europeans. However, our study showed that genetic risk scores in East Asians were similar to those in Europeans, which may explain why the global projected number of people with AMD by 2040 is in largest for East Asians, including Koreans.

A non-synonymous variant rs12614 of complement factor B associated with risk of chronic hepatitis B in a Korean population

Background

Hepatitis B is known to cause several forms of liver diseases including chronic hepatitis B (CHB), and hepatocellular carcinoma. Previous genome-wide association study of CHB risk has demonstrated that rs12614 of complement factor B (CFB) was significantly associated with CHB risk. In this study, fine-mapping study of previously reported GWAS single nucleotide polymorphism (SNP; CFB rs12614) was performed to validate genetic effect of rs12614 on CHB susceptibility and identify possible additional causal variants around rs12614 in a Korean population. This association study was conducted in order to identify genetic effects of CFB single nucleotide polymorphisms (SNPs) and to identify additional independent CHB susceptible causal markers within a Korean population.

Methods

A total of 10 CFB genetic polymorphisms were selected and genotyped in 1716 study subjects comprised of 955 CHB patients and 761 population controls.

Results

A non-synonymous variant, rs12614 (Arg32Trp) in exon2 of CFB, had significant associations with risk of CHB (odds ratio = 0.43, P = 5.91 × 10^− 10). Additional linkage disequilibrium and conditional analysis confirmed that rs12614 had independent genetic effect on CHB susceptibility with previously identified CHB markers. The genetic risk scores (GRSs) were calculated and the CHB patients had higher GRSs than the population controls. Moreover, OR was found to increase significantly with cumulative GRS.

Conclusions

rs12614 showed significant genetic effect on CHB risk within the Korean population. As such rs12614 may be used as a possible causal genetic variant for CHB susceptibility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12881-020-01177-w.

Polygenic Risk Score: Clinically Useful Tool for Prediction of Cardiovascular Disease and Benefit from Lipid-Lowering Therapy?

Improvement in risk prediction of atherosclerotic cardiovascular disease (ASCVD) using information on the genetic predisposition at an individual level might offer new possibilities for the successful management of such complex trait. Latest developments in genetic research with the conduction of genome-wide association studies have facilitated a broader utility of polygenic risk score (PRS) as a potent risk prognosticator, being strongly associated with future cardiovascular events. Although its discriminative ability beyond traditional risk factors is still a matter of controversy, PRS possesses at least comparable risk information to that provided by traditional risk tools. More importantly, increased genetic risk for ASCVD might be discovered at younger ages, much longer before conventional risk factors become manifest, thereby providing a potent instrument for aggressive primordial and primary prevention in those at high risk. Furthermore, there is strong evidence that inherited risk may be successfully modulated by a healthy lifestyle or medication use (e.g., statins or PCSK-9 inhibitors). Here, we provide a short overview of the current research related to the possible application of PRS in clinical routine and critically discuss existing pitfalls, which still limit a widespread utility of PRS outside a research setting.

Genetic Determinants of Weight Loss After Bariatric Surgery

BACKGROUND

The weight loss after bariatric surgery shows considerable individual variation. Twin studies of response to dietary interventions and studies of bariatric surgery patients suggest that genetic differences may play a role. This study aimed to examine the effect of three genetic risk scores on the inter-individual variation in excess body mass index loss (EBMIL) after Roux-en-Y gastric bypass. Furthermore, we searched among known adiposity-related single nucleotide polymorphisms (SNPs) for genetic determinants of the inter-individual variation in EBMIL.

METHODS

Patients with morbid obesity underwent Roux-en-Y gastric bypass and were genotyped (n = 577). Two genetic risk scores for weight loss after bariatric surgery and a genetic risk score for body mass index were calculated. Associations between the genetic risk scores and EBMIL were evaluated. Lasso regression was performed on 126 SNPs known to be associated with adiposity.

RESULTS

The average EBMIL was 76.9% (range 21.7-149.2%). EBMIL was 81.1% (SD 20.6) and 73.9% (SD 21.7) in the high and low tertile groups of a genetic risk score for weight loss. Patients with a low genetic risk score for body mass index (in the lowest 5% percentile) had an EBMIL of 68.8% (SD 20.6, p = 0.018). Thirteen adiposity-related SNPs were identified to associate with EBMIL through lasso regression.

DISCUSSION

A genetic risk score was associated with EBMIL after bariatric surgery, but may not yet be applicable to clinical practice. Patients genetically predisposed to low body mass index had lower weight loss after bariatric surgery.

Contributions of Interactions Between Lifestyle and Genetics on Coronary Artery Disease Risk

PURPOSE OF THE REVIEW

To summarize current knowledge on interactions between genetic variants and lifestyle factors (G×L) associated with the development of coronary artery disease (CAD) and prioritize future research.

RECENT FINDINGS

Genetic risk and combined lifestyle factors and behaviors have a log-additive effect on the risk of developing CAD. First, we describe genetic and lifestyle factors associated with CAD and then focus on G×L interactions. The majority of G×L interaction studies are small-scale candidate gene studies that lack replication and therefore provide spurious results. Only a few studies, of which most use genetic risk scores or genome-wide approaches to test interactions, are robust in number and analysis strategy. These studies provide evidence for the existence of G×L interactions in the development of CAD. Further G×L interactions studies are important as they contribute to our understanding of disease pathophysiology and possibly provide insights for improving interventions or personalized recommendations.

Genome-wide estimates of heritability and genetic correlations in essential tremor

INTRODUCTION

Despite considerable efforts to identify disease-causing and risk factors contributing to essential tremor (ET), no comprehensive assessment of heritable risk has been performed to date.

METHODS

We use GREML-LDMS to estimate narrow-sense heritability due to additive effects (h²) and GREMLd to calculate non-additive heritability due to dominance variance (δ²) using data from 1,751 ET cases and 5,311 controls. We evaluate heritability per 10 Mb segments across the genome and assess the impact of Parkinson's disease (PD) misdiagnosis on heritability estimates. We apply genetic risk score (GRS) from PD and restless legs syndrome (RLS) to explore its contribution to ET risk and further assess genetic correlations with 832 traits by Linkage disequilibrium score regression.

RESULTS

We estimated ET narrow-sense heritability to be h² = 75.5% (s.e = ±0.075). In contrast, dominance variance showed insignificant effect on the overall estimates. Heritability split by 10 Mb regions revealed increased estimates at chromosomes 6 and 21. The proportion of genetic variance due to PD misdiagnosed cases was estimated to be 5.33%. PD and RLS GRS were not significantly predictive of ET case-control status.

CONCLUSIONS

We show for the first time that ET is a highly heritable condition in which additive common variability plays a prominent role. Chromosomes 6 and 21 may contain causative risk variants influencing susceptibility to ET. Despite overlapping symptomatology, ET does not seem to share genetic etiologies with PD or RLS. Our study suggests that most of ET genetic component is yet to be discovered and future GWAS will reveal additional risk factors contributing to ET.

Genetic profiling revealed an increased risk of venous thrombosis in the Hungarian Roma population

BACKGROUND

Besides modifiable risk factors, genetic susceptibility may also explain the high cardiovascular disease burden of the Roma population.

OBJECTIVES

Aim of this study was to define the genetic susceptibility of Hungarian Roma to venous thrombosis (VT) and comparing it to that of the general population.

METHODS

Fifty-two SNPs associated with VT (in F2, F5, F9, F11, F15, FGA, FGB, FGG, CYP4V2, KLKB1 and vWF) were selected and analyzed in the group of Roma (N = 962) and general (N = 1492) subjects collected by cross-sectional studies. Allele frequencies and genetic risk scores (GRS, unweighted and weighted) were computed for the study groups and compared to estimate the joint effects of SNPs.

RESULTS

The majority of the susceptible alleles were more prevalent in the Roma population, and both GRS and wGRS were found to be significantly higher in Roma than in the general population (GRS: 41.83 ± 5.78 vs. 41.04 ± 6.04; wGRS: 7.78 ± 1.28 vs. 7.46 ± 1.33, p = .001). Only 2.39% of subjects in the Roma population were in the bottom fifth of the wGRS (wGRS≤0.19) compared with 3.62% of those in the general population (p = .080); 2.88% of the general subjects were in the top fifth of the wGRS (wGRS≥10.02), while 4.26% of the Roma population were (p = .066).

CONCLUSION

In conclusion, the Roma population seems to have increased genetic susceptibility to VT. This might have important implications in the future in identifying possible new opportunities for targeted prevention and treatment for those subgroups in the populations who are at greater risk for VT development.

Genetic disease risks can be misestimated across global populations

BACKGROUND

Accurate assessment of health disparities requires unbiased knowledge of genetic risks in different populations. Unfortunately, most genome-wide association studies use genotyping arrays and European samples. Here, we integrate whole genome sequence data from global populations, results from thousands of genome-wide association studies (GWAS), and extensive computer simulations to identify how genetic disease risks can be misestimated.

RESULTS

In contrast to null expectations, we find that risk allele frequencies at known disease loci are significantly different for African populations compared to other continents. Strikingly, ancestral risk alleles are found at 9.51% higher frequency in Africa, and derived risk alleles are found at 5.40% lower frequency in Africa. By simulating GWAS with different study populations, we find that non-African cohorts yield disease associations that have biased allele frequencies and that African cohorts yield disease associations that are relatively free of bias. We also find empirical evidence that genotyping arrays and SNP ascertainment bias contribute to continental differences in risk allele frequencies. Because of these causes, polygenic risk scores can be grossly misestimated for individuals of African descent. Importantly, continental differences in risk allele frequencies are only moderately reduced if GWAS use whole genome sequences and hundreds of thousands of cases and controls. Finally, comparisons between uncorrected and corrected genetic risk scores reveal the benefits of considering whether risk alleles are ancestral or derived.

CONCLUSIONS

Our results imply that caution must be taken when extrapolating GWAS results from one population to predict disease risks in another population.

High Genetic Risk Scores of ASIC2, MACROD2, CHRM3, and C2orf83 Genetic Variants Associated with Polycystic Ovary Syndrome Impair Insulin Sensitivity and Interact with Energy Intake in Korean Women

BACKGROUND

We explored the genetic variants that were associated with polycystic ovary syndrome (PCOS) by genome-wide association study (GWAS) and evaluated the association of genetic risk scores (GRS) of the selected genetic variants with insulin resistance and the interaction of the GRS with nutrient intake to develop insulin resistance.

METHODS

The 6 genetic variants involved in brain and nervous system (acid sensing ion channel subunit 2 rs8071961, rs1988598, and rs16589, macro domain containing 2 rs7262810 CHRM3 rs1867265 and chromosome 2 open reading frame 83 rs11889798) were selected from a GWAS of the PCOS study. GRS of the 6 single nucleotide polymorphisms was calculated in 3,723 Korean women in the Ansan/Ansung cohort of KARE study.

RESULTS

Fasting serum insulin and C-reactive protein (CRP) levels, homeostasis model assessment of insulin resistance (HOMA-IR), and psychological stress levels were significantly higher in the high-GRS group than the low-GRS group. However, serum-free T4 levels were significantly lower in the high-GRS group. HOMA-IR and CRP were higher OR (1.129 and 1.382) in the high-GRS group than the low-GRS group after adjusted for covariates. There was a significant interaction between GRS and daily energy intake (p = 0.004). The OR (1.233) for HOMA-IR was higher in the high-GRS group than the low-GRS group only in the group with lower energy intakes based on estimated energy requirement.

CONCLUSION

Women with high-GRS for PCOS had increased risk of insulin resistance and low energy intake did not protect against the elevation of insulin resistance in women with high GRS. Low energy intake might be protective against PCOS in carriers with low and medium GRS.

Genetic endowments, parental resources and adult health: Evidence from the Young Finns Study

This paper uses longitudinal survey data linked to administrative registers to examine socioeconomic gradients in health, particularly whether the effects of genetic endowments interact with the socioeconomic resources of the parental household. We find that genetic risk scores contribute to adult health measured by biomarkers. This result is consistent with the findings from genome-wide association studies. Socioeconomic gradients in health differ based on biomarker and resource measures. Family education is negatively related to obesity and the waist-hip ratio, and family income is negatively related to low-density lipoprotein cholesterol and triglyceride levels. Parental resources do not modify the effects of genetic endowment on adult health. However, there is evidence for gene-family income interactions for triglyceride levels, particularly among women.

Relative contribution of type 1 and type 2 diabetes loci to the genetic etiology of adult-onset, non-insulin-requiring autoimmune diabetes

BACKGROUND

In adulthood, autoimmune diabetes can present as non-insulin-requiring diabetes, termed as 'latent autoimmune diabetes in adults' (LADA). In this study, we investigated established type 1 diabetes (T1D) and type 2 diabetes (T2D) genetic loci in a large cohort of LADA cases to assess where LADA is situated relative to these two well-characterized, classic forms of diabetes.

METHODS

We tested the association of T1D and T2D GWAS-implicated loci in 978 LADA cases and 1057 non-diabetic controls of European ancestry using a linear mixed model. We then compared the associations of T1D and T2D loci between LADA and T1D and T2D cases, respectively. We quantified the difference in genetic risk between each given disease at each locus, and also calculated genetic risk scores to quantify how genetic liability to T1D and T2D distinguished LADA cases from controls.

RESULTS

Overall, our results showed that LADA is genetically more similar to T1D, with the exception of an association at the T2D HNF1A locus. Several T1D loci were associated with LADA, including the major histocompatibility complex region, as well as at PTPN22, SH2B3, and INS. Contrary to previous studies, the key T2D risk allele at TCF7L2 (rs7903146-T) had a significantly lower frequency in LADA cases, suggesting that this locus does not play a role in LADA etiology. When constrained on antibody status, the similarity between LADA and T1D became more apparent; however, the HNF1A and TCF7L2 observations persisted.

CONCLUSION

LADA is genetically closer to T1D than T2D, although the genetic load of T1D risk alleles is less than childhood-onset T1D, particularly at the major histocompatibility complex region, potentially accounting for the later disease onset. Our results show that the genetic spectrum of T1D extends into adult-onset diabetes, where it can clinically masquerade as T2D. Furthermore, T2D genetic risk plays a small role in LADA, with a degree of evidence for the HNF1A locus, highlighting the potential for genetic risk scores to contribute towards defining diabetes subtypes.

Genetic pleiotropy between age-related macular degeneration and 16 complex diseases and traits

BACKGROUND

Age-related macular degeneration (AMD) is a common condition of vision loss with disease development strongly influenced by environmental and genetic factors. Recently, 34 loci were associated with AMD at genome-wide significance. So far, little is known about a genetic overlap between AMD and other complex diseases or disease-relevant traits.

METHODS

For each of 60 complex diseases/traits with publicly available genome-wide significant association data, the lead genetic variant per independent locus was extracted and a genetic score was calculated for each disease/trait as the weighted sum of risk alleles. The association with AMD was estimated based on 16,144 AMD cases and 17,832 controls using logistic regression.

RESULTS

Of the respective disease/trait variance, the 60 genetic scores explained on average 4.8% (0.27-20.69%) and 16 of them were found to be significantly associated with AMD (Q-values < 0.01, p values from < 1.0 × 10^-16 to 1.9 × 10^-3). Notably, an increased risk for AMD was associated with reduced risk for cardiovascular diseases, increased risk for autoimmune diseases, higher HDL and lower LDL levels in serum, lower bone-mineral density as well as an increased risk for skin cancer. By restricting the analysis to 1824 variants initially used to compute the 60 genetic scores, we identified 28 novel AMD risk variants (Q-values < 0.01, p values from 1.1 × 10^-7 to 3.0 × 10^-4), known to be involved in cardiovascular disorders, lipid metabolism, autoimmune diseases, anthropomorphic traits, ocular disorders, and neurological diseases. The latter variants represent 20 novel AMD-associated, pleiotropic loci. Genes in the novel loci reinforce previous findings strongly implicating the complement system in AMD pathogenesis.

CONCLUSIONS

We demonstrate a substantial overlap of the genetics of several complex diseases/traits with AMD and provide statistically significant evidence for an additional 20 loci associated with AMD. This highlights the possibility that so far unrelated pathologies may have disease pathways in common.

Genetic risk scores, sex and dietary factors interact to alter serum uric acid trajectory among African-American urban adults

Serum uric acid (SUA), a causative agent for gout among others, is affected by both genetic and dietary factors, perhaps differentially by sex. We evaluated cross-sectional (SUAbase) and longitudinal (SUArate) associations of SUA with a genetic risk score (GRS), diet and sex. We then tested the interactive effect of GRS, diet and sex on SUA. Longitudinal data on 766 African-American urban adults participating in the Healthy Aging in Neighborhood of Diversity across the Lifespan study were used. In all, three GRS for SUA were created from known SUA-associated SNP (GRSbase (n 12 SNP), GRSrate (n 3 SNP) and GRStotal (n 15 SNP)). Dietary factors included added sugar, total alcohol, red meat, total fish, legumes, dairy products, caffeine and vitamin C. Mixed-effects linear regression models were conducted. SUAbase was higher among men compared with that among women, and increased with GRStotal tertiles. SUArate was positively associated with legume intake in women (γ=+0·14; 95 % CI +0·06, +0·22, P=0·001) and inversely related to dairy product intake in both sexes combined (γ=-0·042; 95 % CI -0·075, -0·009), P=0·010). SUAbase was directly linked to alcohol consumption among women (γ=+0·154; 95 % CI +0·046, +0·262, P=0·005). GRSrate was linearly related to SUArate only among men. Legume consumption was also positively associated with SUArate within the GRStotal's lowest tertile. Among women, a synergistic interaction was observed between GRSrate and red meat intake in association with SUArate. Among men, a synergistic interaction between low vitamin C and genetic risk was found. In sum, sex-diet, sex-gene and gene-diet interactions were detected in determining SUA. Further similar studies are needed to replicate our findings.

Genetic susceptibility for air pollution-induced airway inflammation in the SALIA study

BACKGROUND

Long-term air pollution exposure has been associated with chronic inflammation providing a link to the development of chronic health effects. Furthermore, there is evidence that pathways activated by endoplasmatic reticulum (ER) stress induce airway inflammation and thereby play an important role in the pathogenesis of inflammatory diseases.

OBJECTIVE

We investigated the role of genetic variation of the ER stress pathway on air pollution-induced inflammation.

METHODS

We used the follow-up examination of the German SALIA study (N=402, age 68-79 years). Biomarkers of inflammation were determined in induced sputum. We calculated biomarker-specific weighted genetic risk scores (GRS) out of eight ER stress related single nucleotide polymorphisms and tested their interaction with PM_2.5, PM_2.5 absorbance, PM₁₀ and NO₂ exposure on inflammation by adjusted linear regression.

RESULTS

Genetic variation of the ER stress pathway was associated with higher concentration of inflammation-related biomarkers (levels of leukotriene (LT)B₄, tumor necrosis factor-α (TNF-α), the total number of cells and nitric oxide (NO) derivatives). Furthermore, we observed a significant interaction between air pollution exposure and the ER stress risk score on the concentration of inflammation-related biomarkers. The strongest gene-environment interaction was found for LTB₄ (PM_2.5: p-value=0.002, PM_2.5 absorbance: p-value=0.002, PM₁₀: p-value=0.001 and NO₂: p-value=0.004). Women with a high GRS had a 38% (95%-CI: 16-64%) higher LTB₄ level for an increase of 2.06μg/m³(IQR) in PM_2.5 (no associations in women with a low GRS).

CONCLUSION

These results indicate that genetic variation in the ER stress pathway might play a role in air pollution induced inflammation in the lung.

Risk prediction by genetic risk scores for coronary heart disease is independent of self-reported family history

Aims

Genetic risk scores (GRSs) have been associated with coronary heart disease (CHD) in large studies. We asked whether expanding an established 27-variant GRS (GRS27) to a 50-variant GRS (GRS50) improved CHD prediction and whether GRSs are independent of self-reported family history of CHD.

Methods and results

The association between GRSs and incident CHD was assessed in Cox models adjusting for established risk factors in 23 595 participants of the Malmö Diet and Cancer study—a prospective, population-based study. During a median follow-up of 14.4 years, 2213 participants experienced a first CHD event. After adjustment for established risk factors, both GRS27 and GRS50 were associated with incident CHD [hazard ratio (HR) = 1.70 for high (top quintile) vs. low (bottom quintile) of GRS27; 95% confidence interval (CI): 1.48–1.94; P_trend = 1.6 × 10⁻¹⁵ and HR = 1.92 for GRS50; 95% CI: 1.67–2.20; P_trend = 6.2 × 10⁻²²]. Adding 23 single nucleotide polymorphisms (SNPs) to GRS27 improved risk prediction (P = 3 × 10⁻⁶). Further adjustment for self-reported family history did not appreciably change the risk estimates of either GRS27 (HR = 1.65; 95% CI: 1.45–1.89) or GRS50 (HR = 1.87; 95% CI: 1.63–2.14). The addition of GRS50 to established risk factors, including self-reported family history, improved discrimination (P < 0.0001) and reclassification (continuous net reclassification improvement index = 0.17, P < 0.0001). In young participants (below median age), those with high GRS50 had 2.4-fold greater risk (95% CI: 1.85–3.12) than those with low GRS50.

Conclusion

The addition of 23 SNPs to an existing GRS27 improved CHD risk prediction and was independent of self-reported family history. Coronary heart disease risk assessment by GRS could be particularly useful in young individuals.

The Long-Term Consequences of Vietnam-Era Conscription and Genotype on Smoking Behavior and Health

Research is needed to understand the extent to which environmental factors moderate links between genetic risk and the development of smoking behaviors. The Vietnam-era draft lottery offers a unique opportunity to investigate whether genetic susceptibility to smoking is influenced by risky environments in young adulthood. Access to free or reduced-price cigarettes coupled with the stress of military life meant conscripts were exposed to a large, exogenous shock to smoking behavior at a young age. Using data from the Health and Retirement Study (HRS), we interact a genetic risk score for smoking initiation with instrumented veteran status in an instrumental variables (IV) framework to test for genetic moderation (i.e. heterogeneous treatment effects) of veteran status on smoking behavior and smoking-related morbidities. We find evidence that veterans with a high genetic predisposition for smoking were more likely to have been smokers, smoke heavily, and are at a higher risk of being diagnosed with cancer or hypertension at older ages. Smoking behavior was significantly attenuated for high-risk veterans who attended college after the war, indicating post-service schooling gains from veterans' use of the GI Bill may have reduced tobacco consumption in adulthood.