Biology subjects

Ong, K.

Publications and source records attributed to Ong, K..

8 recordsLinked to original sources

bioRxiv2025

Genetic impacts on within-pair DNA methylation variance in monozygotic twins capture gene-environment interactions and cell-type effects

BackgroundGenetic variants that are associated with phenotypic variability, or variance quantitative trait loci (vQTLs), have been detected for multiple human traits. Gene-environment interactions can lead to differential phenotypic variability across genotype groups, therefore, genetic variants that interact with environmental exposures can manifest as vQTLs. Although changes in DNA methylation variability have been observed in several diseases, vQTLs for methylation levels (vmeQTL) have not yet been explored in depth. ResultsWe optimize the value of monozygotic (MZ) twin studies to identify and replicate vmeQTLs for blood DNA methylation variance at 358 CpGs in 988 adult MZ twin pairs from two European twin registries. Over a third of vmeQTLs captured identical vmeQTL-environmental factor interactions in both datasets, and the majority of interactions were observed with blood cell counts. Correspondingly, over 60% of CpGs affected by genotype-monocyte and genotype-T cell interactions replicated as CpGs affected by genetic effects in the relevant cell type in an independent dataset. Most vmeQTLs also replicated in 1,348 UK non-twin adults and showed longitudinal stability in a sample subset. Integrating gene expression and phenotype association results identified multiple vmeQTLs that capture GxE effects relevant to human health. Examples include vmeQTLs interacting with blood cell type to influence DNA methylation in FAM65A, NAPRT, and CSGALNACT1 underlying immune disease susceptibility and progression. ConclusionOur findings identify novel genetic effects on human DNA methylation variability within a unique MZ twin study design. The results show the potential of vmeQTLs to identify gene-environment interactions and provide novel insights into complex traits.

genetics↗

bioRxiv2023

Fetally-encoded GDF15 and maternal GDF15 sensitivity are major determinants of nausea and vomiting in human pregnancy

Human pregnancy is frequently accompanied by nausea and vomiting that may become severe and life-threatening, as in hyperemesis gravidarum (HG), the cause of which is unknown. Growth Differentiation Factor-15 (GDF15), a hormone known to act on the hindbrain to cause emesis, is highly expressed in the placenta and its levels in maternal blood rise rapidly in pregnancy. Variants in the maternal GDF15 gene are associated with HG. Here we report that fetal production of GDF15, and maternal sensitivity to it, both contribute substantially to the risk of HG. We found that the great majority of GDF15 in maternal circulation is derived from the feto-placental unit and that higher GDF15 levels in maternal blood are associated with vomiting and are further elevated in patients with HG. Conversely, we found that lower levels of GDF15 in the non-pregnant state predispose women to HG. A rare C211G variant in GDF15 which strongly predisposes mothers to HG, particularly when the fetus is wild-type, was found to markedly impair cellular secretion of GDF15 and associate with low circulating levels of GDF15 in the non-pregnant state. Consistent with this, two common GDF15 haplotypes which predispose to HG were associated with lower circulating levels outside pregnancy. The administration of a long-acting form of GDF15 to wild-type mice markedly reduced subsequent responses to an acute dose, establishing that desensitisation is a feature of this system. GDF15 levels are known to be highly and chronically elevated in patients with beta thalassemia. In women with this disorder, reports of symptoms of nausea or vomiting in pregnancy were strikingly diminished. Our findings support a causal role for fetal derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by pre-pregnancy exposure to GDF15, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

genetics↗

bioRxiv2022

Systemic coagulopathy drives host lethality in a new Drosophila tumor model

Malignant tumors trigger a complex network of inflammatory and wound repair responses, prompting Dvoraks characterization of tumors as wounds that never heal 1. Some of these responses lead to profound defects in blood clotting, such as Disseminated Intravascular Coagulopathy (DIC), which correlate with poor prognoses 2-4. Here, we demonstrate that a new tumor model in Drosophila provokes phenotypes that recapitulate coagulopathies observed in patients. Fly ovarian tumors overproduce multiple secreted components of the clotting cascade and trigger hypercoagulation of fly blood (hemolymph). Hypercoagulation occurs shortly after tumor induction and is transient; it is followed by a hypocoagulative state that is defective in wound healing. Cellular clotting regulators accumulate on the tumor over time and are depleted from the body, suggesting that hypocoagulation is caused by malignant growth exhaustion of host clotting components. Interestingly, clinical studies have suggested that lethality in patients with high serum levels of clotting components can be independent of thrombotic events 5,6. We show that rescuing coagulopathy improves survival of tumor-bearing flies, despite the fact that flies have an open circulatory system. Our work establishes a platform for identifying alternative mechanisms by which tumor-driven coagulopathy triggers early mortality, as well as exploring other conserved mechanisms of host responses to chronic wounds.

developmental biology↗

bioRxiv2020

Genome-wide analysis identifies genetic effects on reproductive success and ongoing natural selection at the FADS locus.

Identifying genetic determinants of reproductive success may highlight mechanisms underlying fertility and also identify alleles under present-day selection. Using data in 785,604 individuals of European ancestry, we identify 43 genomic loci associated with either number of children ever born (NEB) or childlessness. These loci span diverse aspects of reproductive biology across the life course, including puberty timing, age at first birth, sex hormone regulation and age at menopause. Missense alleles in ARHGAP27 were associated with increased NEB but reduced reproductive lifespan, suggesting a trade-off between reproductive ageing and intensity. As NEB is one component of evolutionary fitness, our identified associations indicate loci under present-day natural selection. Accordingly, we find that NEB-increasing alleles have increased in frequency over the past two generations. Furthermore, integration with data from ancient selection scans identifies a unique example of an allele--FADS1/2 gene locus--that has been under selection for thousands of years and remains under selection today. Collectively, our findings demonstrate that diverse biological mechanisms contribute to reproductive success, implicating both neuro-endocrine and behavioural influences.

genetics↗

bioRxiv2019

Infectious DNA clone technology and inoculation strategy for Rose Rosette Virus that includes all seven segments of the negative-strand RNA genome

Rose rosette virus (RRV) is an Emaravirus, a negative-sense RNA virus with a 7-segmented genome that is enclosed by a double membrane. While the genome sequences of many emaraviruses are reported, there is negligible information concerning virus replication and movement in host plants. Computational methods determined that RNA1 encoded the RNA dependent RNA polymerase (RdRp), RNA2 encoded glycoprotein precursor, and the RNA3 encoded the nucleocapsid (N), all share significant homologies with similar proteins of the Orthobunyavirus family. The RRV terminal UTR sequences are complementary and share significant identity with the UTR sequences of Bunyamwera virus. We report a minireplicon system and a full length infectious clone of RRV, which are the first for any emaravirus species. The photoreversible fluorescent iLOV protein was used to replace the RNA5 open reading frame (R5-iLOV). We demonstrate that agro-infiltration of Nicotiana benthamiana leaves to deliver RNA1, RNA3, and R5-iLOV cDNAs led to iLOV expression. A mutation was introduced into the RdRp active site and iLOV expression was eliminated. Delivery of four segments or seven segments of the RRV infectious clone produced systemic infection in N. benthamiana and rose plants. iLOV was also fused to the glycoprotein precursor (R2-iLOV). Using confocal microscopy, the R2-iLOV was seen in spherical bodies along membrane strands inside N. benthamiana epidermal cells. This new technology will enable future research to functionally characterize the RRV proteins, to study the virus-host interactions governing local and systemic infection, and examine the subcellular functions of the Gc. IMPORTANCERRV has emerged as a severe threat to cultivated roses, causing millions of dollars in losses to commercial producers. The majority of the viral gene products have not been researched or characterized until now. We constructed a minireplicon system and an infectious clone of the seven-segmented RRV genome that is contained in a binary vector and delivered by Agrobacterium. This technology has been slow to develop for viruses with negative-strand RNA genomes. It has been especially tricky for plant viruses with multicomponent negative-strand RNA genomes. We report the first reverse genetic system for a member of the genus Emaravirus, Rose rosette virus (RRV). We introduced the iLOV fluorescent protein as a fusion to the Gc protein and as a replacement for the open reading frame in genome segment 5. This game-changing reverse genetic system creates new opportunities for studying negative-strand RNA viruses in plants.

microbiology↗

bioRxiv2018

Large-Scale Genome-Wide Meta Analysis of Polycystic Ovary Syndrome Suggests Shared Genetic Architecture for Different Diagnosis Criteria.

Polycystic ovary syndrome (PCOS) is a disorder characterized by hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. Affected women frequently have metabolic disturbances including insulin resistance and dysregulation of glucose homeostasis. PCOS is diagnosed with two different sets of diagnostic criteria, resulting in a phenotypic spectrum of PCOS cases. The genetic similarities between cases diagnosed with different criteria have been largely unknown. Previous studies in Chinese and European subjects have identified 16 loci associated with risk of PCOS. We report a meta-analysis from 10,074 PCOS cases and 103,164 controls of European ancestry and characterisation of PCOS related traits. We identified 3 novel loci (near PLGRKT, ZBTB16 and MAPRE1), and provide replication of 11 previously reported loci. Identified variants were associated with hyperandrogenism, gonadotropin regulation and testosterone levels in affected women. Genetic correlations with obesity, fasting insulin, type 2 diabetes, lipid levels and coronary artery disease indicate shared genetic architecture between metabolic traits and PCOS. Mendelian randomization analyses suggested variants associated with body mass index, fasting insulin, menopause timing, depression and male-pattern balding play a causal role in PCOS. Only one locus differed in its association by diagnostic criteria, otherwise the genetic architecture was similar between PCOS diagnosed by self-report and PCOS diagnosed by NIH or Rotterdam criteria across common variants at 13 loci.

genetics↗

bioRxiv2017

Elucidating the genetic architecture of reproductive ageing in the Japanese population

Population studies over the past decade have successfully elucidated the genetic architecture of reproductive ageing. However, those studies were largely limited to European ancestries, restricting the generalizability of the findings and overlooking possible key genes poorly captured by common European genetic variation. Here, in up to 67,029 women of Japanese ancestry, we report 26 loci (all P<5x10{macron}8) for puberty timing or age at menopause, representing the first loci for reproductive ageing in any non-European population. Highlighted genes for menopause include GNRH1, which supports a primary, rather than passive, role for hypothalamic-pituitary GnRH signalling in the timing of menopause. For puberty timing, we demonstrate an aetiological role for receptor-like protein tyrosine phosphatases by combining evidence across population genetics and pre- and peri-pubertal changes in hypothalamic gene expression in rodent and primate models. Furthermore, our findings demonstrate widespread differences in allele frequencies and effect estimates between Japanese and European populations, highlighting the benefits and challenges of large-scale trans-ethnic approaches.

genetics↗

bioRxiv2017

Replication and characterization of CADM2 and MSRA genes on human behavior

Progress identifying the genetic determinants of personality has historically been slow, with candidate gene studies and small-scale genome-wide association studies yielding few reproducible results. In the UK Biobank study, genetic variants in CADM2 and MSRA were recently shown to influence risk taking behavior and irritability respectively, representing some of the first genomic loci to be associated with aspects of personality. We extend this observation by performing a personality \"phenome-scan\" across 16 traits in up to 140,487 participants from 23andMe for these two genes. Heritability estimates for these traits ranged from 5-19%, with both CADM2 and MSRA demonstrating significant effects on multiple personality types. These associations covered all aspects of the big five personality domains, including specific facet traits such as compliance, altruism, anxiety and activity / energy. This study both confirms and extends the original observations, highlighting the role of genetics in aspects of mental health and behavior.

genetics↗