Publications by authors named "Irina R Tikhonova"

11 Publications

  • Page 1 of 1

Combining genomic and epidemiological data to compare the transmissibility of SARS-CoV-2 lineages.

medRxiv 2021 Jul 2. Epub 2021 Jul 2.

Emerging SARS-CoV-2 variants have shaped the second year of the COVID-19 pandemic and the public health discourse around effective control measures. Evaluating the public health threat posed by a new variant is essential for appropriately adapting response efforts when community transmission is detected. However, this assessment requires that a true comparison can be made between the new variant and its predecessors because factors other than the virus genotype may influence spread and transmission. In this study, we develop a framework that integrates genomic surveillance data to estimate the relative effective reproduction number (R ) of co-circulating lineages. We use Connecticut, a state in the northeastern United States in which the SARS-CoV-2 variants B.1.1.7 and B.1.526 co-circulated in early 2021, as a case study for implementing this framework. We find that the R of B.1.1.7 was 6-10% larger than that of B.1.526 in Connecticut in the midst of a COVID-19 vaccination campaign. To assess the generalizability of this framework, we apply it to genomic surveillance data from New York City and observe the same trend. Finally, we use discrete phylogeography to demonstrate that while both variants were introduced into Connecticut at comparable frequencies, clades that resulted from introductions of B.1.1.7 were larger than those resulting from B.1.526 introductions. Our framework, which uses open-source methods requiring minimal computational resources, may be used to monitor near real-time variant dynamics in a myriad of settings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1101/2021.07.01.21259859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8259915PMC
July 2021

Exome sequencing implicates genetic disruption of prenatal neuro-gliogenesis in sporadic congenital hydrocephalus.

Nat Med 2020 11 19;26(11):1754-1765. Epub 2020 Oct 19.

Departments of Neurosurgery, Engineering Science & Mechanics, and Physics; Center for Neural Engineering and Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.

Congenital hydrocephalus (CH), characterized by enlarged brain ventricles, is considered a disease of excessive cerebrospinal fluid (CSF) accumulation and thereby treated with neurosurgical CSF diversion with high morbidity and failure rates. The poor neurodevelopmental outcomes and persistence of ventriculomegaly in some post-surgical patients highlight our limited knowledge of disease mechanisms. Through whole-exome sequencing of 381 patients (232 trios) with sporadic, neurosurgically treated CH, we found that damaging de novo mutations account for >17% of cases, with five different genes exhibiting a significant de novo mutation burden. In all, rare, damaging mutations with large effect contributed to ~22% of sporadic CH cases. Multiple CH genes are key regulators of neural stem cell biology and converge in human transcriptional networks and cell types pertinent for fetal neuro-gliogenesis. These data implicate genetic disruption of early brain development, not impaired CSF dynamics, as the primary pathomechanism of a significant number of patients with sporadic CH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41591-020-1090-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7871900PMC
November 2020

Mutations disrupting neuritogenesis genes confer risk for cerebral palsy.

Nat Genet 2020 10 28;52(10):1046-1056. Epub 2020 Sep 28.

Henan Key Laboratory of Child Brain Injury, Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China.

In addition to commonly associated environmental factors, genomic factors may cause cerebral palsy. We performed whole-exome sequencing of 250 parent-offspring trios, and observed enrichment of damaging de novo mutations in cerebral palsy cases. Eight genes had multiple damaging de novo mutations; of these, two (TUBA1A and CTNNB1) met genome-wide significance. We identified two novel monogenic etiologies, FBXO31 and RHOB, and showed that the RHOB mutation enhances active-state Rho effector binding while the FBXO31 mutation diminishes cyclin D levels. Candidate cerebral palsy risk genes overlapped with neurodevelopmental disorder genes. Network analyses identified enrichment of Rho GTPase, extracellular matrix, focal adhesion and cytoskeleton pathways. Cerebral palsy risk genes in enriched pathways were shown to regulate neuromotor function in a Drosophila reverse genetics screen. We estimate that 14% of cases could be attributed to an excess of damaging de novo or recessive variants. These findings provide evidence for genetically mediated dysregulation of early neuronal connectivity in cerebral palsy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41588-020-0695-1DOI Listing
October 2020

Mutations in Chromatin Modifier and Ephrin Signaling Genes in Vein of Galen Malformation.

Neuron 2019 02 18;101(3):429-443.e4. Epub 2018 Dec 18.

Division of Nephrology and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, and Department of Medicine, Harvard Medical School, Boston, MA, USA.

Normal vascular development includes the formation and specification of arteries, veins, and intervening capillaries. Vein of Galen malformations (VOGMs) are among the most common and severe neonatal brain arterio-venous malformations, shunting arterial blood into the brain's deep venous system through aberrant direct connections. Exome sequencing of 55 VOGM probands, including 52 parent-offspring trios, revealed enrichment of rare damaging de novo mutations in chromatin modifier genes that play essential roles in brain and vascular development. Other VOGM probands harbored rare inherited damaging mutations in Ephrin signaling genes, including a genome-wide significant mutation burden in EPHB4. Inherited mutations showed incomplete penetrance and variable expressivity, with mutation carriers often exhibiting cutaneous vascular abnormalities, suggesting a two-hit mechanism. The identified mutations collectively account for ∼30% of studied VOGM cases. These findings provide insight into disease biology and may have clinical implications for risk assessment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuron.2018.11.041DOI Listing
February 2019

De novo mutations in histone-modifying genes in congenital heart disease.

Nature 2013 Jun 12;498(7453):220-3. Epub 2013 May 12.

Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA.

Congenital heart disease (CHD) is the most frequent birth defect, affecting 0.8% of live births. Many cases occur sporadically and impair reproductive fitness, suggesting a role for de novo mutations. Here we compare the incidence of de novo mutations in 362 severe CHD cases and 264 controls by analysing exome sequencing of parent-offspring trios. CHD cases show a significant excess of protein-altering de novo mutations in genes expressed in the developing heart, with an odds ratio of 7.5 for damaging (premature termination, frameshift, splice site) mutations. Similar odds ratios are seen across the main classes of severe CHD. We find a marked excess of de novo mutations in genes involved in the production, removal or reading of histone 3 lysine 4 (H3K4) methylation, or ubiquitination of H2BK120, which is required for H3K4 methylation. There are also two de novo mutations in SMAD2, which regulates H3K27 methylation in the embryonic left-right organizer. The combination of both activating (H3K4 methylation) and inactivating (H3K27 methylation) chromatin marks characterizes 'poised' promoters and enhancers, which regulate expression of key developmental genes. These findings implicate de novo point mutations in several hundreds of genes that collectively contribute to approximately 10% of severe CHD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nature12141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3706629PMC
June 2013

Mutations in kelch-like 3 and cullin 3 cause hypertension and electrolyte abnormalities.

Nature 2012 Jan 22;482(7383):98-102. Epub 2012 Jan 22.

Department of Genetics and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510, USA.

Hypertension affects one billion people and is a principal reversible risk factor for cardiovascular disease. Pseudohypoaldosteronism type II (PHAII), a rare Mendelian syndrome featuring hypertension, hyperkalaemia and metabolic acidosis, has revealed previously unrecognized physiology orchestrating the balance between renal salt reabsorption and K(+) and H(+) excretion. Here we used exome sequencing to identify mutations in kelch-like 3 (KLHL3) or cullin 3 (CUL3) in PHAII patients from 41 unrelated families. KLHL3 mutations are either recessive or dominant, whereas CUL3 mutations are dominant and predominantly de novo. CUL3 and BTB-domain-containing kelch proteins such as KLHL3 are components of cullin-RING E3 ligase complexes that ubiquitinate substrates bound to kelch propeller domains. Dominant KLHL3 mutations are clustered in short segments within the kelch propeller and BTB domains implicated in substrate and cullin binding, respectively. Diverse CUL3 mutations all result in skipping of exon 9, producing an in-frame deletion. Because dominant KLHL3 and CUL3 mutations both phenocopy recessive loss-of-function KLHL3 mutations, they may abrogate ubiquitination of KLHL3 substrates. Disease features are reversed by thiazide diuretics, which inhibit the Na-Cl cotransporter in the distal nephron of the kidney; KLHL3 and CUL3 are expressed in this location, suggesting a mechanistic link between KLHL3 and CUL3 mutations, increased Na-Cl reabsorption, and disease pathogenesis. These findings demonstrate the utility of exome sequencing in disease gene identification despite the combined complexities of locus heterogeneity, mixed models of transmission and frequent de novo mutation, and establish a fundamental role for KLHL3 and CUL3 in blood pressure, K(+) and pH homeostasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nature10814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278668PMC
January 2012

Genetic diagnosis of neuroacanthocytosis disorders using exome sequencing.

Mov Disord 2012 Apr 28;27(4):539-43. Epub 2011 Oct 28.

Department of Neurology, James J Peters Veterans Affairs Medical Center, Bronx, New York 10468, USA.

Neuroacanthocytoses are neurodegenerative disorders marked by phenotypic and genetic heterogeneity. There are several associated genetic loci, and many defects, including gene deletions and insertions, and missense, nonsense, and splicing mutations, have been found spread over hundreds of kilobases of genomic DNA. In some cases, specific diagnosis is unclear, particularly in the early stages of disease or when there is an atypical presentation. Determination of the precise genetic defect allows assignment of the diagnosis and permits carrier detection and genetic counseling. The objective of this report was to utilize exome sequencing for genetic diagnosis in the neuroacanthocytosis syndromes. Genomic DNA from 2 patients with clinical features of chorea-acanthocytosis was subjected to targeted exon capture. Captured DNA was subjected to ultrahigh throughput next-generation sequencing. Sequencing data were assembled, filtered against known human variant genetic databases, and results were analyzed. Both patients were compound heterozygotes for mutations in the VPS13A gene, the gene associated with chorea-acanthocytosis. Patient 1 had a 4-bp deletion that removes the 5' donor splice site of exon 58 and a nucleotide substitution that disrupts the 5' donor splice site of exon 70. Patient 2 had a dinucleotide deletion in exon 16 and a dinucleotide insertion in exon 33. No mutations were identified in the XK, PANK2, or JPH3 gene loci. Exome sequencing is a valuable diagnostic tool in the neuroacanthocytosis syndromes. These studies may provide a better understanding of the function of the associated proteins and provide insight into the pathogenesis of these disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mds.24020DOI Listing
April 2012

Genetic diagnosis by whole exome capture and massively parallel DNA sequencing.

Proc Natl Acad Sci U S A 2009 Nov 27;106(45):19096-101. Epub 2009 Oct 27.

Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA.

Protein coding genes constitute only approximately 1% of the human genome but harbor 85% of the mutations with large effects on disease-related traits. Therefore, efficient strategies for selectively sequencing complete coding regions (i.e., "whole exome") have the potential to contribute to the understanding of rare and common human diseases. Here we report a method for whole-exome sequencing coupling Roche/NimbleGen whole exome arrays to the Illumina DNA sequencing platform. We demonstrate the ability to capture approximately 95% of the targeted coding sequences with high sensitivity and specificity for detection of homozygous and heterozygous variants. We illustrate the utility of this approach by making an unanticipated genetic diagnosis of congenital chloride diarrhea in a patient referred with a suspected diagnosis of Bartter syndrome, a renal salt-wasting disease. The molecular diagnosis was based on the finding of a homozygous missense D652N mutation at a position in SLC26A3 (the known congenital chloride diarrhea locus) that is virtually completely conserved in orthologues and paralogues from invertebrates to humans, and clinical follow-up confirmed the diagnosis. To our knowledge, whole-exome (or genome) sequencing has not previously been used to make a genetic diagnosis. Five additional patients suspected to have Bartter syndrome but who did not have mutations in known genes for this disease had homozygous deleterious mutations in SLC26A3. These results demonstrate the clinical utility of whole-exome sequencing and have implications for disease gene discovery and clinical diagnosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.0910672106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2768590PMC
November 2009

Performance comparison of one-color and two-color platforms within the MicroArray Quality Control (MAQC) project.

Nat Biotechnol 2006 Sep;24(9):1140-50

National Center for Toxicological Research, US Food & Drug Administration, 3900 NCTR Rd., Jefferson, Arkansas 72079, USA.

Microarray-based expression profiling experiments typically use either a one-color or a two-color design to measure mRNA abundance. The validity of each approach has been amply demonstrated. Here we provide a simultaneous comparison of results from one- and two-color labeling designs, using two independent RNA samples from the Microarray Quality Control (MAQC) project, tested on each of three different microarray platforms. The data were evaluated in terms of reproducibility, specificity, sensitivity and accuracy to determine if the two approaches provide comparable results. For each of the three microarray platforms tested, the results show good agreement with high correlation coefficients and high concordance of differentially expressed gene lists within each platform. Cumulatively, these comparisons indicate that data quality is essentially equivalent between the one- and two-color approaches and strongly suggest that this variable need not be a primary factor in decisions regarding experimental microarray design.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nbt1242DOI Listing
September 2006
-->