Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Common variants in CYP2R1 and GC genes predict vitamin D concentrations in healthy Danish children and adults.

Environmental factors such as diet, intake of vitamin D supplements and exposure to sunlight are known to influence serum vitamin D concentrations. Genetic epidemiology of vitamin D is in its infancy and a better understanding on how genetic variation influences vitamin D concentration is needed. We aimed to analyse previously reported vitamin D-related polymorphisms in relation to serum 25(OH)D concentrations in 201 healthy Danish families with dependent children in late summer in Denmark. Serum 25(OH)D concentrations and a total of 25 SNPs in GC, VDR, CYP2R1, CYP24A1, CYP27B1, C10or88 and DHCR7/NADSYN1 genes were analysed in 758 participants. Genotype distributions were in Hardy-Weinberg equilibrium for the adult population for all the studied polymorphisms. Four SNPs in CYP2R1 (rs1562902, rs7116978, rs10741657 and rs10766197) and six SNPs in GC (rs4588, rs842999, rs2282679, rs12512631, rs16846876 and rs17467825) were statistically significantly associated with serum 25(OH)D concentrations in children, adults and all combined. Several of the SNPs were in strong linkage disequilibrium, and the associations were driven by CYP2R1-rs10741657 and rs10766197, and by GC-rs4588 and rs842999. Genetic risk score analysis showed that carriers with no risk alleles of CYP2R1-rs10741657 and rs10766197, and/or GC rs4588 and rs842999 had significantly higher serum 25(OH)D concentrations compared to carriers of all risk alleles. To conclude, our results provide supporting evidence that common polymorphisms in GC and CYP2R1 are associated with serum 25(OH)D concentrations in the Caucasian population and that certain haplotypes may predispose to lower 25(OH)D concentrations in late summer in Denmark

Dose-dependent relationship between genotype GG, GX and XX of rs842999 and serum 25(OH)D concentrations.

<p>X-axis stands for genotype GG (GG), GX (GC or GA) and XX (CC, CA or AA) of rs842999. Y-axis stand for serum 25(OH)D (nmol/L). Errors bars stand for 95%-confidence interval and serum 25(OH)D concentrations are given as geometric means. Linear mixed models with family as a random factor, adjusted for age, sex, BMI, ski and sun holidays, solarium use at least once a week, dietary vitamin D intake, multivitamin and vitamin D supplement users was conducted to compare rs842999 genotypes with serum 25(OH)D concentrations. There was a dose-dependent relationship between serum 25(OH)D concentrations and carriers of none, one or two copies of the G-allele. Carriers of two copies of the G-allele, had higher serum 25(OH)D concentrations compared to carriers with only one G-allele or non-carriers in children, adults and all combined, respectively.</p

Distribution of <i>GC</i> haplotype combinations and serum 25(OH)D concentrations in children, adults and all combined.

<p>Bold numbers represent significant P values.</p><p>Haplotype combinations were manually inferred and numbered. Homozygote haplotype combinations were numbered 11, 22, 33, 44 and 55. The combinations of the heterozygote haplotypes (12 to 45) were given by one number of each homozygote haplotype e.g. 1 + 2 = 12.</p>1<p><i>M</i> major allele, <i>m</i> minor allele.</p>2<p>Raw geometric mean of serum 25(OH)D concentrations (nmol/L) and corresponding 95%-confidence interval.</p>3<p>Adjusted geometric mean of 25(OH)D concentrations (nmol/L) and corresponding 95%-confidence interval. Linear mixed models with family as a random factor, adjusted for age, sex, BMI, holiday, use of solarium, dietary vitamin D intake, use of multivitamin and vitamin D supplements.</p>adj<p>Adjusted P values. Haplotype combination 44 was excluded in the linear mixed model due to inadequate participants carrying this haplotype combination.</p

Basic characteristics of the individual SNP and the association with serum 25(OH)D concentrations in children, adults and all combined.

<p>Bold numbers represent significant P values.</p><p><i>SNP</i> single nucleotide polymorphism (ordered by position), <i>MAF</i> minor allele frequency for the adult population in procent, <i>HWE</i> P-values for Hardy-Weinberg equilibrium in the adult population, <i>M/m</i> major and minor alleles, <i>Gt</i> genotype, <i>Mean</i>, raw serum 25(OH)D concentrations were log-transformed to approximate a normal distribution an given as geometric mean (nmol/L), <i>95% CI</i> 95%-confident interval.</p>1<p>Unadjusted P values.</p>2<p>Adjusted P values. Linear mixed models with family as a random factor, adjusted for age, sex, BMI, ski and sun holidays, use of solarium, dietary vitamin D intake, use of multivitamin and vitamin D supplementation.</p