Browsing by Author "Towbin, Jeffrey"

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    Genetic architecture of laterality defects revealed by whole exome sequencing
    (Springer Nature, 2019-04) Li, Alexander H.; Hanchard, Neil A.; Azamian, Mahshid; D’Alessandro, Lisa C. A.; Coban-Akdemir, Zeynep; Lopez, Keila N.; Hall, Nancy J.; Dickerson, Heather; Nicosia, Annarita; Fernbach, Susan; Boone, Philip M.; Gambin, Tomaz; Karaca, Ender; Gu, Shen; Yuan, Bo; Jhangiani, Shalini N.; Doddapaneni, HarshaVardhan; Hu, Jianhong; Dinh, Huyen; Jayaseelan, Joy; Muzny, Donna; Lalani, Seema; Towbin, Jeffrey; Penny, Daniel; Fraser, Charles; Martin, James; Lupski, James R.; Gibbs, Richard A.; Boerwinkle, Eric; Ware, Stephanie M.; Belmont, John W.; Pediatrics, School of Medicine
    Aberrant left-right patterning in the developing human embryo can lead to a broad spectrum of congenital malformations. The causes of most laterality defects are not known, with variants in established genes accounting for <20% of cases. We sought to characterize the genetic spectrum of these conditions by performing whole-exome sequencing of 323 unrelated laterality cases. We investigated the role of rare, predicted-damaging variation in 1726 putative laterality candidate genes derived from model organisms, pathway analyses, and human phenotypes. We also evaluated the contribution of homo/hemizygous exon deletions and gene-based burden of rare variation. A total of 28 candidate variants (26 rare predicted-damaging variants and 2 hemizygous deletions) were identified, including variants in genes known to cause heterotaxy and primary ciliary dyskinesia (ACVR2B, NODAL, ZIC3, DNAI1, DNAH5, HYDIN, MMP21), and genes without a human phenotype association, but with prior evidence for a role in embryonic laterality or cardiac development. Sanger validation of the latter variants in probands and their parents revealed no de novo variants, but apparent transmitted heterozygous (ROCK2, ISL1, SMAD2), and hemizygous (RAI2, RIPPLY1) variant patterns. Collectively, these variants account for 7.1% of our study subjects. We also observe evidence for an excess burden of rare, predicted loss-of-function variation in PXDNL and BMS1- two genes relevant to the broader laterality phenotype. These findings highlight potential new genes in the development of laterality defects, and suggest extensive locus heterogeneity and complex genetic models in this class of birth defects.
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    Genetic Testing Resources and Practice Patterns Among Pediatric Cardiomyopathy Programs
    (Springer, 2025) Godown, Justin; Kim, Emily H.; Everitt, Melanie D.; Chung, Wendy K.; Lytrivi, Irene D.; Kirmani, Sonya; Kantor, Paul F.; Ware, Stephanie M.; Ballweg, Jean A.; Lal, Ashwin K.; Bansal, Neha; Towbin, Jeffrey; Lipshultz, Steven E.; Lee, Teresa M.; Pediatrics, School of Medicine
    The use of genetic testing has enhanced the diagnostic accuracy of heritable genetic cardiomyopathies. However, it remains unclear how genetic information is interpreted and incorporated into clinical practice for children with cardiomyopathy. The primary aim of this study was to understand how clinical practice differs regarding sequence variant classifications amongst pediatric cardiologists who treat children with cardiomyopathy. A secondary aim was to understand the availability of genetic testing and counseling resources across participating pediatric cardiomyopathy programs. An electronic survey was distributed to pediatric heart failure, cardiomyopathy, or heart transplantation physicians between August and September 2022. A total of 106 individual providers from 68 unique centers responded to the survey. Resources for genetic testing and genetic counseling vary among large pediatric cardiomyopathy programs. A minority of centers reported having a geneticist (N = 16, 23.5%) or a genetic counselor (N = 21, 31%) on faculty within the division of pediatric cardiology. A total of 9 centers reported having both (13%). Few centers (N = 13, 19%) have a formal process in place to re-engage patients who were previously discharged from cardiology follow-up if variant reclassification would alter clinical management. Clinical practice patterns were uniform in response to pathogenic or likely pathogenic variants but were more variable for variants of uncertain significance. Efforts to better incorporate genetic expertise and resources into the clinical practice of pediatric cardiomyopathy may help to standardize the interpretation of genetic information and better inform clinical decision-making surrounding heritable cardiomyopathies.