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Villani F, Guarracino A, Ward RR, Green T, Emms M, Pravenec M, Prins P, Garrison E, Williams RW, Chen H, Colonna V. Pangenome reconstruction in rats enhances genotype-phenotype mapping and novel variant discovery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575041. [PMID: 38260597 PMCID: PMC10802574 DOI: 10.1101/2024.01.10.575041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The HXB/BXH family of recombinant inbred rat strains is a unique genetic resource that has been extensively phenotyped over 25 years, resulting in a vast dataset of quantitative molecular and physiological phenotypes. We built a pangenome graph from 10x Genomics Linked-Read data for 31 recombinant inbred rats to study genetic variation and association mapping. The pangenome includes 0.2Gb of sequence that is not present the reference mRatBN7.2, confirming the capture of substantial additional variation. We validated variants in challenging regions, including complex structural variants resolving into multiple haplotypes. Phenome-wide association analysis of validated SNPs uncovered variants associated with glucose/insulin levels and hippocampal gene expression. We propose an interaction between Pirl1l1, chromogranin expression, TNF-α levels, and insulin regulation. This study demonstrates the utility of linked-read pangenomes for comprehensive variant detection and mapping phenotypic diversity in a widely used rat genetic reference panel.
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Affiliation(s)
- Flavia Villani
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Andrea Guarracino
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Rachel R Ward
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Science Center
| | - Tomomi Green
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Science Center
| | - Madeleine Emms
- Institute of Genetics and Biophysics, National Research Council, Naples, 80111, Italy
| | - Michal Pravenec
- Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Pjotr Prins
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Erik Garrison
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Robert W. Williams
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Hao Chen
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Science Center
| | - Vincenza Colonna
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA
- Institute of Genetics and Biophysics, National Research Council, Naples, 80111, Italy
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Okamoto F, Chitre AS, Missfeldt Sanches T, Chen D, Munro D, Polesskaya O, Palmer AA. Y and Mitochondrial Chromosomes in the Heterogeneous Stock Rat Population. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.29.566473. [PMID: 38076923 PMCID: PMC10705385 DOI: 10.1101/2023.11.29.566473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Genome-wide association studies typically evaluate the autosomes and sometimes the X Chromosome, but seldom consider the Y or mitochondrial Chromosomes. We genotyped the Y and mitochondrial chromosomes in heterogeneous stock rats (Rattus norvegicus), which were created in 1984 by intercrossing eight inbred strains and have subsequently been maintained as an outbred population for 100 generations. As the Y and mitochondrial Chromosomes do not recombine, we determined which founder had contributed these chromosomes for each rat, and then performed association analysis for all complex traits (n=12,055; intersection of 12,116 phenotyped and 15,042 haplotyped rats). We found the eight founders had 8 distinct Y and 4 distinct mitochondrial Chromosomes, however only two of each were observed in our modern heterogeneous stock rat population (Generations 81-97). Despite the unusually large sample size, the p-value distribution did not deviate from expectations; there were no significant associations for behavioral, physiological, metabolome, or microbiome traits after correcting for multiple comparisons. However, both Y and mitochondrial Chromosomes were strongly associated with expression of a few genes located on those chromosomes, which provided a positive control. Our results suggest that within modern heterogeneous stock rats there are no Y and mitochondrial Chromosomes differences that strongly influence behavioral or physiological traits. These results do not address other ancestral Y and mitochondrial Chromosomes that do not appear in modern heterogeneous stock rats, nor do they address effects that may exist in other rat populations, or in other species.
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Affiliation(s)
- Faith Okamoto
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Apurva S Chitre
- Bioinformatics and System Biology Program, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Thiago Missfeldt Sanches
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Denghui Chen
- Bioinformatics and System Biology Program, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Daniel Munro
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | | | - Oksana Polesskaya
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Abraham A Palmer
- Department of Psychiatry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
- Institute for Genomic Medicine, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
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