Browsing by Subject "Genetics"

Now showing 1 - 10 of 189
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    21st-Century Genetics in Psychiatric Residency Training: How Do We Get There?
    (American Medical Association, 2019-03-01) Besterman, Aaron D.; Moreno-De-Luca, Daniel; Nurnberger, John I., Jr.; Psychiatry, School of Medicine
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    A role for zinc transporter gene SLC39A12 in the nervous system and beyond
    (Elsevier, 2021) Davis, Danielle N.; Strong, Morgan D.; Chambers, Emily; Hart, Matthew D.; Bettaieb, Ahmed; Clarke, Stephen L.; Smith, Brenda J.; Stoecker, Barbara J.; Lucas, Edralin A.; Lin, Dingbo; Chowanadisai, Winyoo; Obstetrics and Gynecology, School of Medicine
    The SLC39A12 gene encodes the zinc transporter protein ZIP12, which is expressed across many tissues and is highly abundant in the vertebrate nervous system. As a zinc transporter, ZIP12 functions to transport zinc across cellular membranes, including cellular zinc influx across the plasma membrane. Genome-wide association and exome sequencing studies have shown that brain susceptibility-weighted magnetic resonance imaging (MRI) intensity is associated with ZIP12 polymorphisms and rare mutations. ZIP12 is required for neural tube closure and embryonic development in Xenopus tropicalis. Frog embryos depleted of ZIP12 by antisense morpholinos develop an anterior neural tube defect and lack viability. ZIP12 is also necessary for neurite outgrowth and mitochondrial function in mouse neural cells. ZIP12 mRNA is increased in brain regions of schizophrenic patients. Outside of the nervous system, hypoxia induces ZIP12 expression in multiple mammalian species, including humans, which leads to endothelial and smooth muscle thickening in the lung and contributes towards pulmonary hypertension. Other studies have associated ZIP12 with other diseases such as cancer. Given that ZIP12 is highly expressed in the brain and that susceptibility-weighted MRI is associated with brain metal content, ZIP12 may affect neurological diseases and psychiatric illnesses such as Parkinson's disease, Alzheimer's disease, and schizophrenia. Furthermore, the induction of ZIP12 and resultant zinc uptake under pathophysiological conditions may be a critical component of disease pathology, such as in pulmonary hypertension. Drug compounds that bind metals like zinc may be able to treat diseases associated with impaired zinc homeostasis and altered ZIP12 function.
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    A single-cell level comparison of human inner ear organoids with the human cochlea and vestibular organs
    (Cell Press, 2023) van der Valk, Wouter H.; van Beelen, Edward S. A.; Steinhart, Matthew R.; Nist-Lund, Carl; Osorio, Daniel; de Groot, John C. M. J.; Sun, Liang; van Benthem, Peter Paul G.; Koehler, Karl R.; Locher, Heiko; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Inner ear disorders are among the most common congenital abnormalities; however, current tissue culture models lack the cell type diversity to study these disorders and normal otic development. Here, we demonstrate the robustness of human pluripotent stem cell-derived inner ear organoids (IEOs) and evaluate cell type heterogeneity by single-cell transcriptomics. To validate our findings, we construct a single-cell atlas of human fetal and adult inner ear tissue. Our study identifies various cell types in the IEOs including periotic mesenchyme, type I and type II vestibular hair cells, and developing vestibular and cochlear epithelium. Many genes linked to congenital inner ear dysfunction are confirmed to be expressed in these cell types. Additional cell-cell communication analysis within IEOs and fetal tissue highlights the role of endothelial cells on the developing sensory epithelium. These findings provide insights into this organoid model and its potential applications in studying inner ear development and disorders.
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    Alcohol reverses the effects of KCNJ6 (GIRK2) noncoding variants on excitability of human glutamatergic neurons
    (Springer Nature, 2023) Popova, Dina; Gameiro-Ros, Isabel; Youssef, Mark M.; Zalamea, Petronio; Morris, Ayeshia D.; Prytkova, Iya; Jadali, Azadeh; Kwan, Kelvin Y.; Kamarajan, Chella; Salvatore, Jessica E.; Xuei, Xiaoling; Chorlian, David B.; Porjesz, Bernice; Kuperman, Samuel; Dick, Danielle M.; Goate, Alison; Edenberg, Howard J.; Tischfield, Jay A.; Pang, Zhiping P.; Slesinger, Paul A.; Hart, Ronald P.; Medical and Molecular Genetics, School of Medicine
    Synonymous and noncoding single nucleotide polymorphisms (SNPs) in the KCNJ6 gene, encoding G protein-gated inwardly rectifying potassium channel subunit 2 (GIRK2), have been linked with increased electroencephalographic frontal theta event-related oscillations (ERO) in subjects diagnosed with alcohol use disorder (AUD). To identify molecular and cellular mechanisms while retaining the appropriate genetic background, we generated induced excitatory glutamatergic neurons (iN) from iPSCs derived from four AUD-diagnosed subjects with KCNJ6 variants ("Affected: AF") and four control subjects without variants ("Unaffected: UN"). Neurons were analyzed for changes in gene expression, morphology, excitability and physiological properties. Single-cell RNA sequencing suggests that KCNJ6 AF variant neurons have altered patterns of synaptic transmission and cell projection morphogenesis. Results confirm that AF neurons express lower levels of GIRK2, have greater neurite area, and elevated excitability. Interestingly, exposure to intoxicating concentrations of ethanol induces GIRK2 expression and reverses functional effects in AF neurons. Ectopic overexpression of GIRK2 alone mimics the effect of ethanol to normalize induced excitability. We conclude that KCNJ6 variants decrease GIRK2 expression and increase excitability and that this effect can be minimized or reduced with ethanol.
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    Allele-specific expression and high-throughput reporter assay reveal functional genetic variants associated with alcohol use disorders
    (Springer Nature, 2021-04) Rao, Xi; Thapa, Kriti S.; Chen, Andy B.; Lin, Hai; Gao, Hongyu; Reiter, Jill L.; Hargreaves, Katherine A.; Ipe, Joseph; Lai, Dongbing; Xuei, Xiaoling; Wang, Yue; Gu, Hongmei; Kapoor, Manav; Farris, Sean P.; Tischfield, Jay; Foroud, Tatiana; Goate, Alison M.; Skaar, Todd C.; Mayfield, R. Dayne; Edenberg, Howard J.; Liu, Yunlong; Medical and Molecular Genetics, School of Medicine
    Genome-wide association studies (GWAS) of complex traits, such as alcohol use disorders (AUD), usually identify variants in non-coding regions and cannot by themselves distinguish whether the associated variants are functional or in linkage disequilibrium with the functional variants. Transcriptome studies can identify genes whose expression differs between alcoholics and controls. To test which variants associated with AUD may cause expression differences, we integrated data from deep RNA-seq and GWAS of four postmortem brain regions from 30 subjects with AUD and 30 controls to analyze allele-specific expression (ASE). We identified 88 genes with differential ASE in subjects with AUD compared to controls. Next, to test one potential mechanism contributing to the differential ASE, we analyzed single nucleotide polymorphisms (SNPs) in the 3′ untranslated regions (3′UTR) of these genes. Of the 88 genes with differential ASE, 61 genes contained 437 SNPs in the 3′UTR with at least one heterozygote among the subjects studied. Using a modified PASSPORT-seq (parallel assessment of polymorphisms in miRNA target-sites by sequencing) assay, we identified 25 SNPs that affected RNA levels in a consistent manner in two neuroblastoma cell lines, SH-SY5Y and SK-N-BE(2). Many of these SNPs are in binding sites of miRNAs and RNA-binding proteins, indicating that these SNPs are likely causal variants of AUD-associated differential ASE. In sum, we demonstrate that a combination of computational and experimental approaches provides a powerful strategy to uncover functionally relevant variants associated with the risk for AUD.
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    Alzheimer’s disease research progress in the Mediterranean region: the Alzheimer’s Association International Conference Satellite Symposium
    (Wiley, 2022) Sexton, Claire; Solis, Michele; Aharon-Peretz, Judith; Alexopoulos, Panagiotis; Apostolova, Liana; Bayen, Eléonore; Birkenhager, Betty; Cappa, Stefano; Constantinidou, Fofi; Fortea, Juan; Gerritsen, Debby L.; Hassanin, Hany I.; Ibanez, Agustin; Ioannidis, Panagiotis; Karageorgiou, Elissaios; Korczyn, Amos; Leroi, Iracema; Lichtwarck, Bjorn; Logroscino, Giancarlo; Lynch, Chris; Mecocci, Patrizia; Molinuevo, Jose Luis; Papatriantafyllou, John; Papegeorgiou, Sokratis; Politis, Antonis; Raman, Rema; Ritchie, Karen; Sanchez-Juan, Pascual; Sano, Mary; Scarmeas, Nikolas; Spiru, Luiza; Stathi, Afroditi; Tsolaki, Magda; Yener, Görsev; Zaganas, Ioannis; Zygouris, Stelios; Carrillo, Maria; Neurology, School of Medicine
    As research and services in the Mediterranean region continue to increase, so do opportunities for global collaboration. To support such collaborations, the Alzheimer's Association was due to hold its seventh Alzheimer's Association International Conference Satellite Symposium in Athens, Greece in 2021. Due to the COVID-19 pandemic, the meeting was held virtually, which enabled attendees from around the world to hear about research efforts in Greece and the surrounding Mediterranean countries. Research updates spanned understanding the biology of, treatments for, and care of people with Alzheimer's disease (AD_ and other dementias. Researchers in the Mediterranean region have outlined the local epidemiology of AD and dementia, and have identified regional populations that may expedite genetic studies. Development of biomarkers is expected to aid early and accurate diagnosis. Numerous efforts have been made to develop culturally specific interventions to both reduce risk of dementia, and to improve quality of life for people living with dementia.
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    An interpretable Alzheimer's disease oligogenic risk score informed by neuroimaging biomarkers improves risk prediction and stratification
    (Frontiers Media, 2023-10-26) Suh, Erica H.; Lee, Garam; Jung, Sang-Hyuk; Wen, Zixuan; Bao, Jingxuan; Nho, Kwangsik; Huang, Heng; Davatzikos, Christos; Saykin, Andrew J.; Thompson, Paul M.; Shen, Li; Kim, Dokyoon; Alzheimer’s Disease Neuroimaging Initiative; Radiology and Imaging Sciences, School of Medicine
    Introduction: Stratification of Alzheimer's disease (AD) patients into risk subgroups using Polygenic Risk Scores (PRS) presents novel opportunities for the development of clinical trials and disease-modifying therapies. However, the heterogeneous nature of AD continues to pose significant challenges for the clinical broadscale use of PRS. PRS remains unfit in demonstrating sufficient accuracy in risk prediction, particularly for individuals with mild cognitive impairment (MCI), and in allowing feasible interpretation of specific genes or SNPs contributing to disease risk. We propose adORS, a novel oligogenic risk score for AD, to better predict risk of disease by using an optimized list of relevant genetic risk factors. Methods: Using whole genome sequencing data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort (n = 1,545), we selected 20 genes that exhibited the strongest correlations with FDG-PET and AV45-PET, recognized neuroimaging biomarkers that detect functional brain changes in AD. This subset of genes was incorporated into adORS to assess, in comparison to PRS, the prediction accuracy of CN vs. AD classification and MCI conversion prediction, risk stratification of the ADNI cohort, and interpretability of the genetic information included in the scores. Results: adORS improved AUC scores over PRS in both CN vs. AD classification and MCI conversion prediction. The oligogenic model also refined risk-based stratification, even without the assistance of APOE, thus reflecting the true prevalence rate of the ADNI cohort compared to PRS. Interpretation analysis shows that genes included in adORS, such as ATF6, EFCAB11, ING5, SIK3, and CD46, have been observed in similar neurodegenerative disorders and/or are supported by AD-related literature. Discussion: Compared to conventional PRS, adORS may prove to be a more appropriate choice of differentiating patients into high or low genetic risk of AD in clinical studies or settings. Additionally, the ability to interpret specific genetic information allows the focus to be shifted from general relative risk based on a given population to the information that adORS can provide for a single individual, thus permitting the possibility of personalized treatments for AD.
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    Angiotensin-related genetic determinants of cardiovascular disease in patients undergoing hemodialysis
    (Oxford University Press, 2019-11) Moe, Sharon M.; Long, Jin; Schwantes-An, Tae-Hwi Linus; Decker, Brian S.; Wetherill, Leah; Edenberg, Howard J.; Xuei, Xiaoling; Vatta, Matteo; Foroud, Tatiana M.; Chertow, Glenn M.; Medicine, School of Medicine
    BACKGROUND: Cardiovascular mortality in patients receiving dialysis remains unacceptably high, with unexplained ancestry differences suggesting a genetic component. METHODS: We analyzed DNA samples from 37% of subjects enrolled in the EValuation Of Cinacalcet Hydrochloride (HCl) Therapy to Lower CardioVascular Events (EVOLVE) trial, a randomized trial conducted in patients receiving hemodialysis with secondary hyperparathyroidism, comparing cinacalcet to placebo on a background of usual care. DNA was analyzed for single-nucleotide polymorphisms (SNPs) in the genes encoding the angiotensin-converting enzyme receptor type I (AGTR1) and angiotensin-converting enzyme (ACE). Survival analyses were conducted separately in European Ancestry (EA) and African Ancestry (AfAn) due to known differences in cardiovascular events, minor alleles for the same variant and the frequency of minor alleles. Our primary determination was a meta-analysis across both races. RESULTS: Meta-analysis showed significant associations between rs5186 in AGTR1 and increased rates by 25-34% for the primary endpoint (composite of death or nonfatal myocardial infarction, hospitalization for unstable angina, heart failure or peripheral vascular event), all-cause mortality, cardiovascular mortality and heart failure; all P < 0.001. Three correlated SNPs in ACE were associated with lower rates of sudden cardiac death (SCD) in EA samples. One ACE SNP, rs4318, only found in the AfAn samples, was associated with a lower rate of SCD in the AfAn samples. CONCLUSIONS: The C allele in rs5186 in AGTR1 was associated with higher rates of death and major cardiovascular events in a meta-analysis of EA and AfAn patients with end-stage kidney disease. SNPs in ACE were associated with SCD.
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    APOE genotype-specific methylation patterns are linked to Alzheimer disease pathology and estrogen response
    (Springer Nature, 2024-02-29) Panitch, Rebecca; Sahelijo, Nathan; Hu, Junming; Nho, Kwangsik; Bennett, David A.; Lunetta, Kathryn L.; Au, Rhoda; Stein, Thor D.; Farrer, Lindsay A.; Jun, Gyungah R.; Radiology and Imaging Sciences, School of Medicine
    The joint effects of APOE genotype and DNA methylation on Alzheimer disease (AD) risk is relatively unknown. We conducted genome-wide methylation analyses using 2,021 samples in blood (91 AD cases, 329 mild cognitive impairment, 1,391 controls) and 697 samples in brain (417 AD cases, 280 controls). We identified differentially methylated levels in AD compared to controls in an APOE genotype-specific manner at 25 cytosine-phosphate-guanine (CpG) sites in brain and 36 CpG sites in blood. Additionally, we identified seven CpG sites in the APOE region containing TOMM40, APOE, and APOC1 genes with P < 5 × 10-8 between APOE ε4 carriers and non-carriers in brain or blood. In brain, the most significant CpG site hypomethylated in ε4 carriers compared to non-carriers was from the TOMM40 in the total sample, while most of the evidence was derived from AD cases. However, the CpG site was not significantly modulating expression of these three genes in brain. Three CpG sites from the APOE were hypermethylated in APOE ε4 carriers in brain or blood compared in ε4 non-carriers and nominally significant with APOE expression in brain. Three CpG sites from the APOC1 were hypermethylated in blood, which one of the 3 CpG sites significantly lowered APOC1 expression in blood using all subjects or ε4 non-carriers. Co-methylation network analysis in blood and brain detected eight methylation networks associated with AD and APOE ε4 status. Five of the eight networks included genes containing network CpGs that were significantly enriched for estradiol perturbation, where four of the five networks were enriched for the estrogen response pathway. Our findings provide further evidence of the role of APOE genotype on methylation levels associated with AD, especially linked to estrogen response pathway.
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    APOL1 G3 variant is associated with cardiovascular mortality and sudden cardiac death in patients receiving maintenance hemodialysis of European Ancestry
    (Karger, 2022) Schwantes-An, Tae-Hwi; Robinson-Cohen, Cassianne; Liu, Sai; Zheng, Neil; Stedman, Margaret; Wetherill, Leah; Edenberg, Howard J.; Vatta, Matteo; Foroud, Tatiana M.; Chertow, Glenn M.; Moe, Sharon M.; Medical and Molecular Genetics, School of Medicine
    Introduction: The G1 and G2 variants in the APOL1 gene convey high risk for the progression of chronic kidney disease in African Americans. The G3 variant in APOL1 is more common in patients of European ancestry (EA); outcomes associated with this variant have not been explored previously in EA patients receiving dialysis. Methods: DNA was collected from approximately half of the patients enrolled in the Evaluation of Cinacalcet HCl Therapy to Lower Cardiovascular Events (EVOLVE) trial and genotyped for the G3 variants. We utilized an additive genetic model to test associations of G3 with the EVOLVE adjudicated endpoints of all-cause mortality, cardiovascular mortality, sudden cardiac death (SCD), and heart failure. EA and African ancestry samples were analyzed separately. Validation was done in the Vanderbilt BioVU using ICD codes for cardiovascular events that parallel the adjudicated endpoints in EVOLVE. Results: In EVOLVE, G3 in EA patients was associated with the adjudicated endpoints of cardiovascular mortality and SCD. In a validation cohort from the Vanderbilt BioVU, cardiovascular events and cardiovascular mortality defined by ICD codes showed similar associations in EA participants who had been on dialysis for 2 to <5 years. Discussion/conclusions: G3 in APOL1 variant was associated with cardiovascular events and cardiovascular mortality in the EA patients receiving dialysis. This suggests that variations in the APOL1 gene that differ in populations of different ancestry may contribute to cardiovascular disease.