👤 Joanna Mm Howson

Sleep is essential for health and regulated by genetic and environmental factors. We perform genome-wide association studies of device-measured sleep duration, efficiency, and accelerometer-derived rapid eye movement (REM) and non-rapid eye movement (NREM) sleep in 80,013 UK Biobank participants. We identify 20 autosomal loci, 12 of which have not been previously reported, including genome-wide significant associations for REM and NREM sleep duration. MEIS1 shows strong opposing effects on REM and NREM durations and is intolerant to loss-of-function mutations, suggesting an essential role in the regulation of REM/NREM sleep balance. Functional enrichment analysis identifies statistically significant pathways related to chromatin remodelling, lipid metabolism, and metal ion homeostasis while tissue enrichment analysis highlights significant signals in the hypothalamus and frontal cortex. Sex-stratified analyses identify distinct loci, including FOXP2 and NRXN3 in females and LRP1B, NPBWR2, and PABPC4 in males. Mendelian randomization supports associations between shorter sleep duration and higher cardiometabolic risk. These findings highlight sex- and phase-specific regulators of human sleep architecture, providing biological insights and potential therapeutic targets. Show less

Lipoprotein(a) (Lp[a]) is an established predictor of cardiovascular risk but associations with secondary events are less certain, and data on understudied ethnic groups are scarce. This study aimed to assess the association between Lp(a) and secondary events and explore variation in Lp(a) levels by ethnicity in first-time acute coronary syndrome (ACS) patients, to inform future risk prediction models. The Multi-Ethnic New Zealand Study of Acute Coronary Syndromes (MENZACS) is a longitudinal multi-centre cohort study of 1900 patients enrolled during their ACS admission. Baseline plasma Lp(a) concentrations were measured using an isoform-insensitive assay measured in nmol/L. The primary outcome was a composite of all-cause mortality or cardiovascular readmission, ascertained through national health datasets. Cox regression models were used to assess the association between Lp(a) levels and outcomes, adjusted for clinical risk factors. The mean age was 61 years, 20 % were female, and 73 % were European, 14 % Māori, 5 % Pacific peoples, 4 % Indian and 3 % other ethnicities. Of 1890 alive at discharge, 493 (26 %) experienced the primary outcome over a median follow-up of 4.9 years. Higher Lp(a) levels were associated with increased risk of secondary events. Compared to the lowest quartile (≤7 nmol/L), the adjusted hazard ratio for the highest quartile (>92 nmol/L) was 1.46 (95 %CI 1.12-1.89, p = 0.004). In this ACS cohort, Lp(a) concentrations varied by ethnicity, being highest amongst Indian participants (median 27 nmol/L) and lowest amongst Māori participants (median 12 nmol/L). Elevated Lp(a) concentrations are associated with secondary events following ACS. Further research is needed to define optimal thresholds for increased risk and explore ethnic-specific implications for secondary prevention. Show less

The aim of this study was to leverage human genetic data to investigate the cardiometabolic effects of glucose-dependent insulinotropic polypeptide (GIP) signalling. Data were obtained from summary statistics of large-scale genome-wide association studies. We examined whether genetic associations for type 2 diabetes liability in the GIP and GIPR genes co-localised with genetic associations for 11 cardiometabolic outcomes. For those outcomes that showed evidence of co-localisation (posterior probability >0.8), we performed Mendelian randomisation analyses to estimate the association of genetically proxied GIP signalling with risk of cardiometabolic outcomes, and to test whether this exceeded the estimate observed when considering type 2 diabetes liability variants from other regions of the genome. Evidence of co-localisation with genetic associations of type 2 diabetes liability at both the GIP and GIPR genes was observed for five outcomes. Mendelian randomisation analyses provided evidence for associations of lower genetically proxied type 2 diabetes liability at the GIP and GIPR genes with lower BMI (estimate in SD units -0.16, 95% CI -0.30, -0.02), C-reactive protein (-0.13, 95% CI -0.19, -0.08) and triacylglycerol levels (-0.17, 95% CI -0.22, -0.12), and higher HDL-cholesterol levels (0.19, 95% CI 0.14, 0.25). For all of these outcomes, the estimates were greater in magnitude than those observed when considering type 2 diabetes liability variants from other regions of the genome. This study provides genetic evidence to support a beneficial role of sustained GIP signalling on cardiometabolic health greater than that expected from improved glycaemic control alone. Further clinical investigation is warranted. All data used in this study are publicly available. The scripts for the analysis are available at: https://github.com/vkarhune/GeneticallyProxiedGIP . Show less

Genome-wide association studies (GWAS) have identified >250 loci for body mass index (BMI), implicating pathways related to neuronal biology. Most GWAS loci represent clusters of common, noncoding variants from which pinpointing causal genes remains challenging. Here we combined data from 718,734 individuals to discover rare and low-frequency (minor allele frequency (MAF) < 5%) coding variants associated with BMI. We identified 14 coding variants in 13 genes, of which 8 variants were in genes (ZBTB7B, ACHE, RAPGEF3, RAB21, ZFHX3, ENTPD6, ZFR2 and ZNF169) newly implicated in human obesity, 2 variants were in genes (MC4R and KSR2) previously observed to be mutated in extreme obesity and 2 variants were in GIPR. The effect sizes of rare variants are ~10 times larger than those of common variants, with the largest effect observed in carriers of an MC4R mutation introducing a stop codon (p.Tyr35Ter, MAF = 0.01%), who weighed ~7 kg more than non-carriers. Pathway analyses based on the variants associated with BMI confirm enrichment of neuronal genes and provide new evidence for adipocyte and energy expenditure biology, widening the potential of genetically supported therapeutic targets in obesity. Show less

We screened variants on an exome-focused genotyping array in >300,000 participants (replication in >280,000 participants) and identified 444 independent variants in 250 loci significantly associated with total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C), low-density-lipoprotein cholesterol (LDL-C), and/or triglycerides (TG). At two loci (JAK2 and A1CF), experimental analysis in mice showed lipid changes consistent with the human data. We also found that: (i) beta-thalassemia trait carriers displayed lower TC and were protected from coronary artery disease (CAD); (ii) excluding the CETP locus, there was not a predictable relationship between plasma HDL-C and risk for age-related macular degeneration; (iii) only some mechanisms of lowering LDL-C appeared to increase risk for type 2 diabetes (T2D); and (iv) TG-lowering alleles involved in hepatic production of TG-rich lipoproteins (TM6SF2 and PNPLA3) tracked with higher liver fat, higher risk for T2D, and lower risk for CAD, whereas TG-lowering alleles involved in peripheral lipolysis (LPL and ANGPTL4) had no effect on liver fat but decreased risks for both T2D and CAD. Show less

Genome-wide association studies have so far identified 56 loci associated with risk of coronary artery disease (CAD). Many CAD loci show pleiotropy; that is, they are also associated with other diseases or traits. This study sought to systematically test if genetic variants identified for non-CAD diseases/traits also associate with CAD and to undertake a comprehensive analysis of the extent of pleiotropy of all CAD loci. In discovery analyses involving 42,335 CAD cases and 78,240 control subjects we tested the association of 29,383 common (minor allele frequency >5%) single nucleotide polymorphisms available on the exome array, which included a substantial proportion of known or suspected single nucleotide polymorphisms associated with common diseases or traits as of 2011. Suggestive association signals were replicated in an additional 30,533 cases and 42,530 control subjects. To evaluate pleiotropy, we tested CAD loci for association with cardiovascular risk factors (lipid traits, blood pressure phenotypes, body mass index, diabetes, and smoking behavior), as well as with other diseases/traits through interrogation of currently available genome-wide association study catalogs. We identified 6 new loci associated with CAD at genome-wide significance: on 2q37 (KCNJ13-GIGYF2), 6p21 (C2), 11p15 (MRVI1-CTR9), 12q13 (LRP1), 12q24 (SCARB1), and 16q13 (CETP). Risk allele frequencies ranged from 0.15 to 0.86, and odds ratio per copy of the risk allele ranged from 1.04 to 1.09. Of 62 new and known CAD loci, 24 (38.7%) showed statistical association with a traditional cardiovascular risk factor, with some showing multiple associations, and 29 (47%) showed associations at p < 1 × 10 We identified 6 loci associated with CAD at genome-wide significance. Several CAD loci show substantial pleiotropy, which may help us understand the mechanisms by which these loci affect CAD risk. Show less

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P < 5 × 10 Show less