👤 Wim A A Vermeulen

The β-amyloid precursor protein-cleaving enzyme 1 (BACE1) inhibitor JNJ-54861911, a candidate for the treatment of Alzheimer's disease, was withdrawn from clinical trials due to drug-induced liver injury (DILI). This paper describes our investigation of the metabolism of JNJ-54861911 to understand the potential contribution to the observed DILI. In human hepatocytes, JNJ-54861911 is metabolized by CYP450 3A4 to a reactive intermediate (RI), which undergoes glutathione (GSH) addition at C6 of the 2-amino-4-methyl-1,3-thiazin-4-yl moiety via glutathione S-transferase α1 (GSTA1) catalysis. Despite the preponderant role of CYP3A4 as an enabler, the adduct has the same level of oxidation as that of JNJ-54861911. The exact mechanism of RI formation might involve a sulfoxide (with further reduction) or tautomeric forms of JNJ-54861911 bearing a reactive thiazinium cation activating both the C2 and C6 positions. The cell pellet from the human hepatocyte incubated with Show less

Lung adenocarcinoma is the most common type of lung cancer. Known risk variants explain only a small fraction of lung adenocarcinoma heritability. Here, we conducted a two-stage genome-wide association study of lung adenocarcinoma of East Asian ancestry (21,658 cases and 150,676 controls; 54.5% never-smokers) and identified 12 novel susceptibility variants, bringing the total number to 28 at 25 independent loci. Transcriptome-wide association analyses together with colocalization studies using a Taiwanese lung expression quantitative trait loci dataset (n = 115) identified novel candidate genes, including FADS1 at 11q12 and ELF5 at 11p13. In a multi-ancestry meta-analysis of East Asian and European studies, four loci were identified at 2p11, 4q32, 16q23, and 18q12. At the same time, most of our findings in East Asian populations showed no evidence of association in European populations. In our studies drawn from East Asian populations, a polygenic risk score based on the 25 loci had a stronger association in never-smokers vs. individuals with a history of smoking (P Show less

The importance of genetic testing for cardiomyopathies has increased in the last decade. However, in heart transplant patients with former cardiomyopathy, genetic testing in retrospect is not routinely performed. We hypothesize that the yield of genetic testing in this population is considerable, and will have a major impact for both patients and relatives. Patients that underwent heart transplantation (HTx) between 1995 and 2020 and were still in follow-up, were offered genetic testing if the primary etiology was non-ischemic cardiomyopathy. Next generation sequencing (NGS) of known cardiomyopathy genes was performed and variants were classified as variant of unknown significance (class 3), likely pathogenic (class 4) or pathogenic (class 5) variant. Of the 99 HTx patients in active follow-up, only 6 patients had a genetic diagnosis at the time of HTx. In this study, 31 selected patients with prior non-ischemic cardiomyopathy underwent genetic testing post HTx. 23/31 patients (74.2%) carried a variant that was classified as class 3 or higher. In 12/31 patients a class 4/5 variant (38.7%) was identified, and in 11/31 patients (35.5%) a class 3 variant. Class 5 Variants in TTN were the most prevalent (7/31), followed by class 5 variants in MYBPC3 (2/31). A positive family history was present in 21/31 (67.7%) and a second precipitating factor (e.g., alcohol abuse, pregnancy) was present in 17/31 patients (54.8%). Diagnostic yield of genetic testing was similar between patients with or without familial history and/or second hit. Through cascade screening 48 family members were screened for presence of a class 4/5 variant, of whom 19 (39.6%) were genotype positive, of whom 10 (52.6%) showed a cardiac phenotype. Appropriate follow-up was offered. Genetic testing for cardiomyopathy genes established a molecular diagnosis in 38.7% of patients post HTx. These results highlight the importance of genetic testing in this population as it is still often overlooked in patients that already underwent HTx in the past. Genetic testing is highly recommended, independent of family history or second precipitating factors, as it might identify relatives at risk. Show less

The heart muscle diseases hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure in young, otherwise healthy, individuals. We conducted genome-wide association studies and multi-trait analyses in HCM (1,733 cases), DCM (5,521 cases) and nine left ventricular (LV) traits (19,260 UK Biobank participants with structurally normal hearts). We identified 16 loci associated with HCM, 13 with DCM and 23 with LV traits. We show strong genetic correlations between LV traits and cardiomyopathies, with opposing effects in HCM and DCM. Two-sample Mendelian randomization supports a causal association linking increased LV contractility with HCM risk. A polygenic risk score explains a significant portion of phenotypic variability in carriers of HCM-causing rare variants. Our findings thus provide evidence that polygenic risk score may account for variability in Mendelian diseases. More broadly, we provide insights into how genetic pathways may lead to distinct disorders through opposing genetic effects. 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

Gut microbiota have been implicated in the development of atherosclerosis and cardiovascular disease. Since the prebiotic inulin is thought to beneficially affect gut microbiota, we aimed to determine the effect of inulin supplementation on atherosclerosis development in APOE*3-Leiden.CETP (E3L.CETP) mice. Female E3L.CETP mice were fed a western-type diet containing 0.1% or 0.5% cholesterol with or without 10% inulin. The effects of inulin were determined on: microbiota composition, cecal short-chain fatty acid (SCFA) levels, plasma lipid levels, atherosclerosis development, hepatic morphology and hepatic inflammation. Inulin with 0.5% dietary cholesterol increased specific bacterial genera and elevated levels of cecal SCFAs, but did not affect plasma cholesterol levels or atherosclerosis development. Surprisingly, inulin resulted in mild hepatic inflammation as shown by increased expression of inflammation markers. However, these effects were not accompanied by increased hepatic macrophage number. Analogously, inulin induced mild steatosis and increased hepatocyte size, but did not affect hepatic triglyceride content. Inulin with 0.1% dietary cholesterol did not affect hepatic morphology, nor hepatic expression of inflammation markers. Overall, inulin did not reduce hypercholesterolemia or atherosclerosis development in E3L.CETP mice despite showing clear prebiotic activity, but resulted in manifestations of hepatic inflammation when combined with a high percentage of dietary cholesterol. Show less

The strong observational association between total homocysteine (tHcy) concentrations and risk of coronary artery disease (CAD) and the null associations in the homocysteine-lowering trials have prompted the need to identify genetic variants associated with homocysteine concentrations and risk of CAD. We tested whether common genetic polymorphisms associated with variation in tHcy are also associated with CAD. We conducted a meta-analysis of genome-wide association studies (GWAS) on tHcy concentrations in 44,147 individuals of European descent. Polymorphisms associated with tHcy (P < 10(⁻⁸) were tested for association with CAD in 31,400 cases and 92,927 controls. Common variants at 13 loci, explaining 5.9% of the variation in tHcy, were associated with tHcy concentrations, including 6 novel loci in or near MMACHC (2.1 × 10⁻⁹), SLC17A3 (1.0 × 10⁻⁸), GTPB10 (1.7 × 10⁻⁸), CUBN (7.5 × 10⁻¹⁰), HNF1A (1.2 × 10⁻¹²)), and FUT2 (6.6 × 10⁻⁹), and variants previously reported at or near the MTHFR, MTR, CPS1, MUT, NOX4, DPEP1, and CBS genes. Individuals within the highest 10% of the genotype risk score (GRS) had 3-μmol/L higher mean tHcy concentrations than did those within the lowest 10% of the GRS (P = 1 × 10⁻³⁶). The GRS was not associated with risk of CAD (OR: 1.01; 95% CI: 0.98, 1.04; P = 0.49). We identified several novel loci that influence plasma tHcy concentrations. Overall, common genetic variants that influence plasma tHcy concentrations are not associated with risk of CAD in white populations, which further refutes the causal relevance of moderately elevated tHcy concentrations and tHcy-related pathways for CAD. Show less

Deficiency of the urea cycle enzyme carbamylphosphate synthetase 1 (CPS1) causes hyperammonemia with a vast range of clinical severity from neonatal onset with early lethality to onset after age 40 with rare episodes of hyperammonemic confusion. The cause for this variability is not understood. We report two patients from one family with highly divergent clinical course, one presenting neonatally with a fatal form and the other at age 45 with benign diet-responsive disease. The patients are compound heterozygous for two mutations of the CPS1 gene, c.3558 + 1G > C and c.4101 + 2T > C. The haplotypes containing each mutation are identical between the two patients, as are the sequences of CPS1 exons and flanking introns. Transcriptional experiments show that the abnormal CPS1 transcripts generated by both mutations are identical in these two patients. We characterize promoter and enhancer sequences of the CPS1 gene and find also in these regions no sequence differences between patients. Finally, we perform cloning experiments and find that in the neonatal-onset case, clones of messenger RNA (mRNA) expressed from the allele carrying the c.4101 + 2T > C mutation are threefold more than clones of mRNA from the allele with the c.3558 + 1G > C mutation, whereas in the adult-onset case the two types of clones are equal, indicating skewed expression towards the c.4101 + 2T > C allele in the neonatal case. Although we are yet to understand the mechanism of this differential expression, our work suggests that allelic imbalance may explain clinical variability in CPS1 deficiency in some families. Show less

Transporters present in the epithelium of the small intestine determine the efficiency by which dietary and biliary cholesterol are taken up into the body and thus control whole-body cholesterol balance. Niemann-Pick C1 Like Protein 1 (Npc1l1) transports cholesterol into the enterocyte, whereas ATP-binding cassette transporters Abca1 and Abcg5/Abcg8 are presumed to be involved in cholesterol efflux from the enterocyte toward plasma HDL and back into the intestinal lumen, respectively. Abca1, Abcg5, and Abcg8 are well-established liver X receptor (LXR) target genes. We examined the effects of a high-fat diet on expression and function of cholesterol transporters in the small intestine in mice. Npc1l1, Abca1, Abcg5, and Abcg8 were all downregulated after 2, 4, and 8 wk on a cholesterol-free, high-fat diet. The high-fat diet did not affect biliary cholesterol secretion but diminished fractional cholesterol absorption from 61 to 42% (P < 0.05). In an acute experiment in which triacylglycerols of unsaturated fatty acids were given by gavage, we found that this downregulation occurs within a 6-h time frame. Studies in LXRalpha-null mice, confirmed by in vitro data, showed that fatty acid-induced downregulation of cholesterol transporters is LXRalpha independent and associated with a posttranslational increase in 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity that reflects induction of cholesterol biosynthesis as well as with a doubling of neutral fecal sterol loss. This study highlights the induction of adaptive changes in small intestinal cholesterol metabolism during exposure to dietary fat. Show less