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Link V, Schraiber JG, Fan C, Dinh B, Mancuso N, Chiang CWK, Edge MD. Tree-based QTL mapping with expected local genetic relatedness matrices. Am J Hum Genet 2023; 110:2077-2091. [PMID: 38065072 PMCID: PMC10716520 DOI: 10.1016/j.ajhg.2023.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 12/18/2023] Open
Abstract
Understanding the genetic basis of complex phenotypes is a central pursuit of genetics. Genome-wide association studies (GWASs) are a powerful way to find genetic loci associated with phenotypes. GWASs are widely and successfully used, but they face challenges related to the fact that variants are tested for association with a phenotype independently, whereas in reality variants at different sites are correlated because of their shared evolutionary history. One way to model this shared history is through the ancestral recombination graph (ARG), which encodes a series of local coalescent trees. Recent computational and methodological breakthroughs have made it feasible to estimate approximate ARGs from large-scale samples. Here, we explore the potential of an ARG-based approach to quantitative-trait locus (QTL) mapping, echoing existing variance-components approaches. We propose a framework that relies on the conditional expectation of a local genetic relatedness matrix (local eGRM) given the ARG. Simulations show that our method is especially beneficial for finding QTLs in the presence of allelic heterogeneity. By framing QTL mapping in terms of the estimated ARG, we can also facilitate the detection of QTLs in understudied populations. We use local eGRM to analyze two chromosomes containing known body size loci in a sample of Native Hawaiians. Our investigations can provide intuition about the benefits of using estimated ARGs in population- and statistical-genetic methods in general.
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Affiliation(s)
- Vivian Link
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Joshua G Schraiber
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Caoqi Fan
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA; Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Bryan Dinh
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA; Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Nicholas Mancuso
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA; Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Charleston W K Chiang
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA; Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael D Edge
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA, USA.
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Link V, Schraiber JG, Fan C, Dinh B, Mancuso N, Chiang CW, Edge MD. Tree-based QTL mapping with expected local genetic relatedness matrices. bioRxiv 2023:2023.04.07.536093. [PMID: 37066144 PMCID: PMC10104234 DOI: 10.1101/2023.04.07.536093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Understanding the genetic basis of complex phenotypes is a central pursuit of genetics. Genome-wide Association Studies (GWAS) are a powerful way to find genetic loci associated with phenotypes. GWAS are widely and successfully used, but they face challenges related to the fact that variants are tested for association with a phenotype independently, whereas in reality variants at different sites are correlated because of their shared evolutionary history. One way to model this shared history is through the ancestral recombination graph (ARG), which encodes a series of local coalescent trees. Recent computational and methodological breakthroughs have made it feasible to estimate approximate ARGs from large-scale samples. Here, we explore the potential of an ARG-based approach to quantitative-trait locus (QTL) mapping, echoing existing variance-components approaches. We propose a framework that relies on the conditional expectation of a local genetic relatedness matrix given the ARG (local eGRM). Simulations show that our method is especially beneficial for finding QTLs in the presence of allelic heterogeneity. By framing QTL mapping in terms of the estimated ARG, we can also facilitate the detection of QTLs in understudied populations. We use local eGRM to identify a large-effect BMI locus, the CREBRF gene, in a sample of Native Hawaiians in which it was not previously detectable by GWAS because of a lack of population-specific imputation resources. Our investigations can provide intuition about the benefits of using estimated ARGs in population- and statistical-genetic methods in general.
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Affiliation(s)
- Vivian Link
- Department of Quantitative and Computational Biology, University of Southern California
| | - Joshua G. Schraiber
- Department of Quantitative and Computational Biology, University of Southern California
| | - Caoqi Fan
- Department of Quantitative and Computational Biology, University of Southern California
- Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California
| | - Bryan Dinh
- Department of Quantitative and Computational Biology, University of Southern California
- Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California
| | - Nicholas Mancuso
- Department of Quantitative and Computational Biology, University of Southern California
- Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California
| | - Charleston W.K. Chiang
- Department of Quantitative and Computational Biology, University of Southern California
- Center for Genetic Epidemiology, Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California
| | - Michael D. Edge
- Department of Quantitative and Computational Biology, University of Southern California
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Sitmukhambetov S, Dinh B, Lai Y, Banigan EJ, Pan Z, Jia X, Chi Y. Development and implementation of a metaphase DNA model for ionizing radiation induced DNA damage calculation. Phys Med Biol 2022; 68:10.1088/1361-6560/aca5ea. [PMID: 36533598 PMCID: PMC9969557 DOI: 10.1088/1361-6560/aca5ea] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/24/2022] [Indexed: 11/25/2022]
Abstract
Objective. To develop a metaphase chromosome model representing the complete genome of a human lymphocyte cell to support microscopic Monte Carlo (MMC) simulation-based radiation-induced DNA damage studies.Approach. We first employed coarse-grained polymer physics simulation to obtain a rod-shaped chromatid segment of 730 nm in diameter and 460 nm in height to match Hi-C data. We then voxelized the segment with a voxel size of 11 nm per side and connected the chromatid with 30 types of pre-constructed nucleosomes and 6 types of linker DNAs in base pair (bp) resolutions. Afterward, we piled different numbers of voxelized chromatid segments to create 23 pairs of chromosomes of 1-5μm long. Finally, we arranged the chromosomes at the cell metaphase plate of 5.5μm in radius to create the complete set of metaphase chromosomes. We implemented the model in gMicroMC simulation by denoting the DNA structure in a four-level hierarchical tree: nucleotide pairs, nucleosomes and linker DNAs, chromatid segments, and chromosomes. We applied the model to compute DNA damage under different radiation conditions and compared the results to those obtained with G0/G1 model and experimental measurements. We also performed uncertainty analysis for relevant simulation parameters.Main results. The chromatid segment was successfully voxelized and connected in bps resolution, containing 26.8 mega bps (Mbps) of DNA. With 466 segments, we obtained the metaphase chromosome containing 12.5 Gbps of DNA. Applying it to compute the radiation-induced DNA damage, the obtained results were self-consistent and agreed with experimental measurements. Through the parameter uncertainty study, we found that the DNA damage ratio between metaphase and G0/G1 phase models was not sensitive to the chemical simulation time. The damage was also not sensitive to the specific parameter settings in the polymer physics simulation, as long as the produced metaphase model followed a similar contact map distribution.Significance. Experimental data reveal that ionizing radiation induced DNA damage is cell cycle dependent. Yet, DNA chromosome models, except for the G0/G1 phase, are not available in the state-of-the-art MMC simulation. For the first time, we successfully built a metaphase chromosome model and implemented it into MMC simulation for radiation-induced DNA damage computation.
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Affiliation(s)
| | - Bryan Dinh
- Department of Physics, the University of Texas at Arlington, Arlington, TX 76019, USA
| | - Youfang Lai
- Department of Physics, the University of Texas at Arlington, Arlington, TX 76019, USA
| | - Edward J. Banigan
- Institute for Medical Engineering & Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zui Pan
- Graduate Nursing, the University of Texas at Arlington, Arlington, TX 76019, USA
| | - Xun Jia
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, MD 21231, USA
| | - Yujie Chi
- Department of Physics, the University of Texas at Arlington, Arlington, TX 76019, USA
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Moeyaert P, Miguirditchian M, Masson M, Dinh B, Hérès X, De Sio S, Sorel C. Experimental and modelling study of ruthenium extraction with tri-n-butylphosphate in the purex process. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2016.10.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gunderson C, Dinh B, Farrell R, Thomas E, Vesely S, Chopra S, McMeekin D, Moore K. Inpatient versus outpatient management of neutropenic fever in gynecologic oncology patients: Does cost really matter? Gynecol Oncol 2013. [DOI: 10.1016/j.ygyno.2013.04.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Malavaud B, Dinh B, Bonnet E, Izopet J, Payen JL, Marchou B. Increased incidence of indinavir nephrolithiasis in patients with hepatitis B or C virus infection. Antivir Ther 2000; 5:3-5. [PMID: 10846585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
MATERIALS AND METHODS A HIV-1 patient database was scanned in March 1998, and 750 patients were identified who had received HAART including indinavir. Of these, 28 cases had nephrolithiasis; and 85 asymptomatic indinavir-treated patients were randomly selected as controls. The characteristics of cases and controls were compared by analysis of variance for quantitative parameters and by Fisher's exact test for classes. RESULTS We observed a significant increase in the incidence of nephrolithiasis in patients co-infected with HIV-1 and either hepatitis C virus (HCV) (HCV RNA-positive) or hepatitis B virus (HBV) (HBs antigen-positive) (odds ratio and 95% confidence intervals: 2.8 and 1.1-7.7), whereas no significant differences were demonstrated between cases and controls with regard to age (42.4 +/- 8.0 versus 39.8 +/- 9.8 years), sex (male patients 70.4 versus 74.1%), duration of HIV-1 infection (8.6 +/- 3.1 versus 7.7 +/- 4.0 years), duration of indinavir treatment (16.1 +/- 5.8 versus 14.1 +/- 5.4 months), AST increase > or = 1.25 of normal (29.6 versus 25.9%), or ALT increase > or = 1.25 of normal (33.3 versus 22.4%). In co-infected patients, ALT increase (> or = 1.25 of normal), but not AST increase, at the time of indinavir initiation was statistically related to the occurrence of nephrolithiasis. CONCLUSIONS We found a significant increase of nephrolithiasis incidence in patients co-infected with HIV-1 and HCV or HBV, which suggests that underlying multifactorial hepatic damage may limit liver catabolism of indinavir, and consequently increase its renal excretion and the risk of nephrolithiasis. Caution is therefore advised when initiating indinavir treatment in HIV patients with evidence of HBV or HCV infection.
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Affiliation(s)
- B Malavaud
- Department of Urology, Centre Hospital Universitaire Purpan, Toulouse, France.
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