Browsing by Author "Jhangiani, Shalini N."

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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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    Lessons learned from additional research analyses of unsolved clinical exome cases
    (BioMed Central, 2017-03-21) Eldomery, Mohammad K.; Coban-Akdemir, Zeynep; Harel, Tamar; Rosenfeld, Jill A.; Gambin, Tomasz; Stray-Pedersen, Asbjørg; Küry, Sébastien; Mercier, Sandra; Lessel, Davor; Denecke, Jonas; Wiszniewski, Wojciech; Penney, Samantha; Liu, Pengfei; Bi, Weimin; Lalani, Seema R.; Schaaf, Christian P.; Wangler, Michael F.; Bacino, Carlos A.; Lewis, Richard Alan; Potocki, Lorraine; Graham, Brett H.; Belmont, John W.; Scaglia, Fernando; Orange, Jordan S.; Jhangiani, Shalini N.; Chiang, Theodore; Doddapaneni, Harsha; Hu, Jianhong; Muzny, Donna M.; Xia, Fan; Beaudet, Arthur L.; Boerwinkle, Eric; Eng, Christine M.; Plon, Sharon E.; Sutton, V. Reid; Gibbs, Richard A.; Posey, Jennifer E.; Yang, Yaping; Lupski, James R.; Department of Pathology and Laboratory Medicine, IU School of Medicine
    BACKGROUND: Given the rarity of most single-gene Mendelian disorders, concerted efforts of data exchange between clinical and scientific communities are critical to optimize molecular diagnosis and novel disease gene discovery. METHODS: We designed and implemented protocols for the study of cases for which a plausible molecular diagnosis was not achieved in a clinical genomics diagnostic laboratory (i.e. unsolved clinical exomes). Such cases were recruited to a research laboratory for further analyses, in order to potentially: (1) accelerate novel disease gene discovery; (2) increase the molecular diagnostic yield of whole exome sequencing (WES); and (3) gain insight into the genetic mechanisms of disease. Pilot project data included 74 families, consisting mostly of parent-offspring trios. Analyses performed on a research basis employed both WES from additional family members and complementary bioinformatics approaches and protocols. RESULTS: Analysis of all possible modes of Mendelian inheritance, focusing on both single nucleotide variants (SNV) and copy number variant (CNV) alleles, yielded a likely contributory variant in 36% (27/74) of cases. If one includes candidate genes with variants identified within a single family, a potential contributory variant was identified in a total of ~51% (38/74) of cases enrolled in this pilot study. The molecular diagnosis was achieved in 30/63 trios (47.6%). Besides this, the analysis workflow yielded evidence for pathogenic variants in disease-associated genes in 4/6 singleton cases (66.6%), 1/1 multiplex family involving three affected siblings, and 3/4 (75%) quartet families. Both the analytical pipeline and the collaborative efforts between the diagnostic and research laboratories provided insights that allowed recent disease gene discoveries (PURA, TANGO2, EMC1, GNB5, ATAD3A, and MIPEP) and increased the number of novel genes, defined in this study as genes identified in more than one family (DHX30 and EBF3). CONCLUSION: An efficient genomics pipeline in which clinical sequencing in a diagnostic laboratory is followed by the detailed reanalysis of unsolved cases in a research environment, supplemented with WES data from additional family members, and subject to adjuvant bioinformatics analyses including relaxed variant filtering parameters in informatics pipelines, can enhance the molecular diagnostic yield and provide mechanistic insights into Mendelian disorders. Implementing these approaches requires collaborative clinical molecular diagnostic and research efforts.