Browsing by Author "Dexheimer, Phillip J."

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    Genetic Causes of Cardiomyopathy in Children: First Results From the Pediatric Cardiomyopathy Genes Study
    (American Heart Association, 2021-05-04) Ware, Stephanie M.; Wilkinson, James D.; Tariq, Muhammad; Schubert, Jeffrey A.; Sridhar, Arthi; Colan, Steven D.; Shi, Ling; Canter, Charles E.; Hsu, Daphne T.; Webber, Steven A.; Dodd, Debra A.; Everitt, Melanie D.; Kantor, Paul F.; Addonizio, Linda J.; Jefferies, John L.; Rossano, Joseph W.; Pahl, Elfriede; Rusconi, Paolo; Chung, Wendy K.; Lee, Teresa; Towbin, Jeffrey A.; Lal, Ashwin K.; Bhatnagar, Surbhi; Aronow, Bruce; Dexheimer, Phillip J.; Martin, Lisa J.; Miller, Erin M.; Sleeper, Lynn A.; Razoky, Hiedy; Czachor, Jason; Lipshultz, Steven E.; Pediatrics, School of Medicine
    Pediatric cardiomyopathy is a genetically heterogeneous disease with substantial morbidity and mortality. Current guidelines recommend genetic testing in children with hypertrophic, dilated, or restrictive cardiomyopathy, but practice variations exist. Robust data on clinical testing practices and diagnostic yield in children are lacking. This study aimed to identify the genetic causes of cardiomyopathy in children and to investigate clinical genetic testing practices. Methods and Results Children with familial or idiopathic cardiomyopathy were enrolled from 14 institutions in North America. Probands underwent exome sequencing. Rare sequence variants in 37 known cardiomyopathy genes were assessed for pathogenicity using consensus clinical interpretation guidelines. Of the 152 enrolled probands, 41% had a family history of cardiomyopathy. Of 81 (53%) who had undergone clinical genetic testing for cardiomyopathy before enrollment, 39 (48%) had a positive result. Genetic testing rates varied from 0% to 97% between sites. A positive family history and hypertrophic cardiomyopathy subtype were associated with increased likelihood of genetic testing (P=0.005 and P=0.03, respectively). A molecular cause was identified in an additional 21% of the 63 children who did not undergo clinical testing, with positive results identified in both familial and idiopathic cases and across all phenotypic subtypes. Conclusions A definitive molecular genetic diagnosis can be made in a substantial proportion of children for whom the cause and heritable nature of their cardiomyopathy was previously unknown. Practice variations in genetic testing are great and should be reduced. Improvements can be made in comprehensive cardiac screening and predictive genetic testing in first-degree relatives. Overall, our results support use of routine genetic testing in cases of both familial and idiopathic cardiomyopathy.
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    Ulcerative colitis mucosal transcriptomes reveal mitochondriopathy and personalized mechanisms underlying disease severity and treatment response
    (Springer Nature, 2019-01-03) Haberman, Yael; Karns, Rebekah; Dexheimer, Phillip J.; Schirmer, Melanie; Somekh, Judith; Jurickova, Ingrid; Braun, Tzipi; Novak, Elizabeth; Bauman, Laura; Collins, Margaret H.; Mo, Angela; Rosen, Michael J.; Bonkowski, Erin; Gotman, Nathan; Marquis, Alison; Nistel, Mason; Rufo, Paul A.; Baker, Susan S.; Sauer, Cary G.; Markowitz, James; Pfefferkorn, Marian D.; Rosh, Joel R.; Boyle, Brendan M.; Mack, David R.; Baldassano, Robert N.; Shah, Sapana; Leleiko, Neal S.; Heyman, Melvin B.; Grifiths, Anne M.; Patel, Ashish S.; Noe, Joshua D.; Aronow, Bruce J.; Kugathasan, Subra; Walters, Thomas D.; Gibson, Greg; Thomas, Sonia Davis; Mollen, Kevin; Shen-Orr, Shai; Huttenhower, Curtis; Xavier, Ramnik J.; Hyams, Jeffrey S.; Denson, Lee A.; Pediatrics, School of Medicine
    Molecular mechanisms driving disease course and response to therapy in ulcerative colitis (UC) are not well understood. Here, we use RNAseq to define pre-treatment rectal gene expression, and fecal microbiota profiles, in 206 pediatric UC patients receiving standardised therapy. We validate our key findings in adult and paediatric UC cohorts of 408 participants. We observe a marked suppression of mitochondrial genes and function across cohorts in active UC, and that increasing disease severity is notable for enrichment of adenoma/adenocarcinoma and innate immune genes. A subset of severity genes improves prediction of corticosteroid-induced remission in the discovery cohort; this gene signature is also associated with response to anti-TNFα and anti-α4β7 integrin in adults. The severity and therapeutic response gene signatures were in turn associated with shifts in microbes previously implicated in mucosal homeostasis. Our data provide insights into UC pathogenesis, and may prioritise future therapies for nonresponders to current approaches.