Browsing by Author "Schaaf, Christian P."

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    De Novo ZMYND8 variants result in an autosomal dominant neurodevelopmental disorder with cardiac malformations
    (Elsevier, 2022-09) Dias, Kerith-Rae; Carlston, Colleen M.; Blok, Laura E. R.; De Hayr , Lachlan; Nawaz, Urwah; Evans, Carey-Anne; Bayrak-Toydemir, Pinar; Htun, Stephanie; Zhu, Ying; Ma, Alan; Lynch, Sally Ann; Moorwood, Catherine; Stals , Karen; Ellard, Sian; Bainbridge, Matthew N.; Friedman, Jennifer; Pappas, John G.; Rabin , Rachel; Nowak, Catherine B.; Douglas, Jessica; Wilson, Theodore E.; Guillen Sacoto, Maria J.; Mullegama, Sureni V.; Palculict , Timothy Blake; Kirk, Edwin P.; Pinner, Jason R.; Edwards, Matthew; Montanari, Francesca; Graziano, Claudio; Pippucci, Tommaso; Dingmann, Bri; Glass , Ian; Mefford , Heather C.; Shimoji , Takeyoshi; Suzuki, Toshimitsu; Yamakawa, Kazuhiro; Streff, Haley; Schaaf, Christian P.; Slavotinek, Anne M.; Voineagu , Irina; Carey, John C.; Buckley, Michael F.; Schenck, Annette; Harvey, Robert J.; Roscioli , Tony; Medical and Molecular Genetics, School of Medicine
    Purpose ZMYND8 encodes a multidomain protein that serves as a central interactive hub for coordinating critical roles in transcription regulation, chromatin remodeling, regulation of super-enhancers, DNA damage response and tumor suppression. We delineate a novel neurocognitive disorder caused by variants in the ZMYND8 gene. Methods An international collaboration, exome sequencing, molecular modeling, yeast two-hybrid assays, analysis of available transcriptomic data and a knockdown Drosophila model were used to characterize the ZMYND8 variants. Results ZMYND8 variants were identified in 11 unrelated individuals; 10 occurred de novo and one suspected de novo; 2 were truncating, 9 were missense, of which one was recurrent. The disorder is characterized by intellectual disability with variable cardiovascular, ophthalmologic and minor skeletal anomalies. Missense variants in the PWWP domain of ZMYND8 abolish the interaction with Drebrin and missense variants in the MYND domain disrupt the interaction with GATAD2A. ZMYND8 is broadly expressed across cell types in all brain regions and shows highest expression in the early stages of brain development. Neuronal knockdown of the Drosophila ZMYND8 ortholog results in decreased habituation learning, consistent with a role in cognitive function. Conclusion We present genomic and functional evidence for disruption of ZMYND8 as a novel etiology of syndromic intellectual disability.
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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.
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    NAHR-mediated copy-number variants in a clinical population: Mechanistic insights into both genomic disorders and Mendelizing traits
    (Cold Spring Harbor Laboratory, 2013) Dittwald, Piotr; Gambin, Tomasz; Szafranski, Przemyslaw; Li, Jian; Amato, Stephen; Divon, Michael Y.; Rodríguez Rojas, Lisa Ximena; Elton, Lindsay E.; Scott, Daryl A.; Schaaf, Christian P.; Torres-Martinez, Wilfredo; Stevens, Abby K.; Rosenfeld, Jill A.; Agadi, Satish; Francis, David; Kang, Sung-Hae L.; Breman, Amy; Lalani, Seema R.; Bacino, Carlos A.; Bi, Weimin; Milosavljevic, Aleksandar; Beaudet, Arthur L.; Patel, Ankita; Shaw, Chad A.; Lupski, James R.; Gambin, Anna; Cheung, Sau Wai; Stankiewicz, Pawel; Medical and Molecular Genetics, School of Medicine
    We delineated and analyzed directly oriented paralogous low-copy repeats (DP-LCRs) in the most recent version of the human haploid reference genome. The computationally defined DP-LCRs were cross-referenced with our chromosomal microarray analysis (CMA) database of 25,144 patients subjected to genome-wide assays. This computationally guided approach to the empirically derived large data set allowed us to investigate genomic rearrangement relative frequencies and identify new loci for recurrent nonallelic homologous recombination (NAHR)-mediated copy-number variants (CNVs). The most commonly observed recurrent CNVs were NPHP1 duplications (233), CHRNA7 duplications (175), and 22q11.21 deletions (DiGeorge/velocardiofacial syndrome, 166). In the ∼25% of CMA cases for which parental studies were available, we identified 190 de novo recurrent CNVs. In this group, the most frequently observed events were deletions of 22q11.21 (48), 16p11.2 (autism, 34), and 7q11.23 (Williams-Beuren syndrome, 11). Several features of DP-LCRs, including length, distance between NAHR substrate elements, DNA sequence identity (fraction matching), GC content, and concentration of the homologous recombination (HR) hot spot motif 5'-CCNCCNTNNCCNC-3', correlate with the frequencies of the recurrent CNVs events. Four novel adjacent DP-LCR-flanked and NAHR-prone regions, involving 2q12.2q13, were elucidated in association with novel genomic disorders. Our study quantitates genome architectural features responsible for NAHR-mediated genomic instability and further elucidates the role of NAHR in human disease.