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Item Correction to: De novo and inherited TCF20 pathogenic variants are associated with intellectual disability, dysmorphic features, hypotonia, and neurological impairments with similarities to Smith-Magenis syndrome(Biomed Central, 2019-03-25) Vetrini, Francesco; McKee, Shane; Rosenfeld, Jill A.; Suri, Mohnish; Lewis, Andrea M.; Nugent, Kimberly Margaret; Roeder, Elizabeth; Littlejohn, Rebecca O.; Holder, Sue; Zhu, Wenmiao; Alaimo, Joseph T.; Graham, Brett; Harris, Jill M.; Gibson, James B.; Pastore, Matthew; McBride, Kim L.; Komara, Makanko; Al-Gazali, Lihadh; Al Shamsi, Aisha; Fanning, Elizabeth A.; Wierenga, Klaas J.; Scott, Daryl A.; Ben-Neriah, Ziva; Meiner, Vardiella; Cassuto, Hanoch; Elpeleg, Orly; Lloyd Holder Jr, J.; Burrage, Lindsay C.; Seaver, Laurie H.; Van Maldergem, Lionel; Mahida, Sonal; Soul, Janet S.; Marlatt, Margaret; Matyakhina, Ludmila; Vogt, Julie; Gold, June-Anne; Park, Soo-Mi; Varghese, Vinod; Lampe, Anne K.; Kumar, Ajith; Lees, Melissa; Holder-Espinasse, Muriel; McConnell, Vivienne; Bernhard, Birgitta; Blair, Ed; Harrison, Victoria; Muzny, Donna M.; Gibbs, Richard A.; Elsea, Sarah H.; Posey, Jennifer E.; Bi, Weimin; Lalani, Seema; Xia, Fan; Yang, Yaping; Eng, Christine M.; Lupski, James R.; Liu, Pengfei; Medical and Molecular Genetics, School of MedicineIt was highlighted that the original article [1] contained a typographical error in the Results section. Subject 17 was incorrectly cited as Subject 1. This Correction article shows the revised statement. The original article has been updated.Item Delineating the molecular and phenotypic spectrum of the SETD1B-related syndrome(Elsevier, 2021-11) Weerts, Marjolein J.A.; Lanko, Kristina; Guzmán-Vega, Francisco J.; Jackson, Adam; Ramakrishnan, Reshmi; Cardona-Londoño, Kelly J.; Peña-Guerra, Karla A.; van Bever, Yolande; van Paassen, Barbara W.; Kievit, Anneke; van Slegtenhorst, Marjon; Allen, Nicholas M.; Kehoe, Caroline M.; Robinson, Hannah K.; Pang, Lewis; Banu, Selina H.; Zaman, Mashaya; Efthymiou, Stephanie; Houlden, Henry; Järvelä, Irma; Lauronen, Leena; Määttä, Tuomo; Schrauwen, Isabelle; Leal, Suzanne M.; Ruivenkamp, Claudia A.L.; Barge-Schaapveld, Daniela Q.C.M.; Peeters-Scholte, Cacha M.P.C.D.; Galehdari, Hamid; Mazaheri, Neda; Sisodiya, Sanjay M.; Harrison, Victoria; Sun, Angela; Thies, Jenny; Pedroza, Luis Alberto; Lara-Taranchenko, Yana; Chinn, Ivan K.; Lupski, James R.; Garza-Flores, Alexandra; McGlothlin, Jeffery; Yang, Lin; Huang, Shaoping; Wang, Xiaodong; Jewett, Tamison; Rosso, Gretchen; Lin, Xi; Mohammed, Shehla; Merritt, J. Lawrence, II.; Mirzaa, Ghayda M.; Timms, Andrew E.; Scheck, Joshua; Elting, Mariet W.; Polstra, Abeltje M.; Schenck, Lauren; Ruzhnikov, Maura R.Z.; Vetro, Annalisa; Montomoli, Martino; Guerrini, Renzo; Koboldt, Daniel C.; Mihalic Mosher, Theresa; Pastore, Matthew T.; McBride, Kim L.; Peng, Jing; Pan, Zou; Willemsen, Marjolein; Koning, Susanne; Turnpenny, Peter D.; de Vries, Bert B.A.; Gilissen, Christian; Pfundt, Rolph; Lees, Melissa; Braddock, Stephen R.; Klemp, Kara C.; Vansenne, Fleur; van Gijn, Marielle E.; Quindipan, Catherine; Deardorff, Matthew A.; Hamm, J. Austin; Putnam, Abbey M.; Baud, Rebecca; Walsh, Laurence; Lynch, Sally A.; Baptista, Julia; Person, Richard E.; Monaghan, Kristin G.; Crunk, Amy; Keller-Ramey, Jennifer; Reich, Adi; Elloumi, Houda Zghal; Alders, Marielle; Kerkhof, Jennifer; McConkey, Haley; Haghshenas, Sadegheh; Maroofian, Reza; Sadikovic, Bekim; Banka, Siddharth; Arold, Stefan T.; Barakat, Tahsin Stefan; Medical and Molecular Genetics, School of MedicinePurpose: Pathogenic variants in SETD1B have been associated with a syndromic neurodevelopmental disorder including intellectual disability, language delay, and seizures. To date, clinical features have been described for 11 patients with (likely) pathogenic SETD1B sequence variants. This study aims to further delineate the spectrum of the SETD1B-related syndrome based on characterizing an expanded patient cohort. Methods: We perform an in-depth clinical characterization of a cohort of 36 unpublished individuals with SETD1B sequence variants, describing their molecular and phenotypic spectrum. Selected variants were functionally tested using in vitro and genome-wide methylation assays. Results: Our data present evidence for a loss-of-function mechanism of SETD1B variants, resulting in a core clinical phenotype of global developmental delay, language delay including regression, intellectual disability, autism and other behavioral issues, and variable epilepsy phenotypes. Developmental delay appeared to precede seizure onset, suggesting SETD1B dysfunction impacts physiological neurodevelopment even in the absence of epileptic activity. Males are significantly overrepresented and more severely affected, and we speculate that sex-linked traits could affect susceptibility to penetrance and the clinical spectrum of SETD1B variants. Conclusion: Insights from this extensive cohort will facilitate the counseling regarding the molecular and phenotypic landscape of newly diagnosed patients with the SETD1B-related syndrome.Item Evidence for replicative mechanism in a CHD7 rearrangement in a patient with CHARGE syndrome(Wiley, 2013-12) Vatta, Matteo; Niu, Zhiyv; Lupski, James R.; Putnam, Philip; Spoonamore, Katherine G.; Fang, Ping; Eng, Christine M.; Willis, Alecia S.; Medical & Molecular Genetics, School of MedicineHaploinsufficiency of CHD7 (OMIM# 608892) is known to cause CHARGE syndrome (OMIM# 214800). Molecular testing supports a definitive diagnosis in approximately 65-70% of cases. Most CHD7 mutations arise de novo, and no mutations affecting exon-7 have been reported to date. We report on an 8-year-old girl diagnosed with CHARGE syndrome that was referred to our laboratory for comprehensive CHD7 gene screening. Genomic DNA from the subject with a suspected diagnosis of CHARGE was isolated from peripheral blood lymphocytes and comprehensive Sanger sequencing, along with deletion/duplication analysis of the CHD7 gene using multiplex ligation-dependent probe amplification (MLPA), was performed. MLPA analysis identified a reduced single probe signal for exon-7 of the CHD7 gene consistent with potential heterozygous deletion. Long-range PCR breakpoint analysis identified a complex genomic rearrangement (CGR) leading to the deletion of exon-7 and breakpoints consistent with a replicative mechanism such as fork stalling and template switching (FoSTeS) or microhomology-mediated break-induced replication (MMBIR). Taken together this represents the first evidence for a CHD7 intragenic CGR in a patient with CHARGE syndrome leading to what appears to be also the first report of a mutation specifically disrupting exon-7. Although likely rare, CGR may represent an overlooked mechanism in subjects with CHARGE syndrome that can be missed by current sequencing and dosage assays.Item 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 MedicineAberrant 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.Item 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 MedicineBACKGROUND: 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.Item Missense variants in TAF1 and developmental phenotypes: Challenges of determining pathogenicity(Wiley, 2019-10-23) Cheng, Hanyin; Capponi, Simona; Wakeling, Emma; Marchi, Elaine; Li, Quan; Zhao, Mengge; Weng, Chunhua; Piatek, Stefan G.; Ahlfors, Helena; Kleyner, Robert; Rope, Alan; Lumaka, Aimé; Lukusa, Prosper; Devriendt, Koenraad; Vermeesch, Joris; Posey, Jennifer E.; Palmer, Elizabeth E.; Murray, Lucinda; Leon, Eyby; Diaz, Jullianne; Worgan, Lisa; Mallawaarachchi, Amali; Vogt, Julie; de Munnik, Sonja A.; Dreyer, Lauren; Baynam, Gareth; Ewans, Lisa; Stark, Zornitza; Lunke, Sebastian; Gonçalves, Ana R.; Soares, Gabriela; Oliveira, Jorge; Fassi, Emily; Willing, Marcia; Waugh, Jeff L.; Faivre, Laurence; Riviere, Jean-Baptiste; Moutton, Sebastien; Mohammed, Shehla; Payne, Katelyn; Walsh, Laurence; Begtrup, Amber; Guillen Sacoto, Maria J.; Douglas, Ganka; Alexander, Nora; Buckley, Michael F.; Mark, Paul R.; Adès, Lesley C.; Sandaradura, Sarah A.; Lupski, James R.; Roscioli, Tony; Agrawal, Pankaj B.; Kline, Antonie D.; Wang, Kai; Timmers, T. Marc; Lyon, Gholson J.; Neurology, School of MedicineWe recently described a new neurodevelopmental syndrome (TAF1/MRXS33 intellectual disability syndrome) (MIM# 300966) caused by pathogenic variants involving the X-linked gene TAF1, which participates in RNA polymerase II transcription. The initial study reported eleven families, and the syndrome was defined as presenting early in life with hypotonia, facial dysmorphia, and developmental delay that evolved into intellectual disability (ID) and/or autism spectrum disorder (ASD). We have now identified an additional 27 families through a genotype-first approach. Familial segregation analysis, clinical phenotyping, and bioinformatics were capitalized on to assess potential variant pathogenicity, and molecular modelling was performed for those variants falling within structurally characterized domains of TAF1. A novel phenotypic clustering approach was also applied, in which the phenotypes of affected individuals were classified using 51 standardized Human Phenotype Ontology (HPO) terms. Phenotypes associated with TAF1 variants show considerable pleiotropy and clinical variability, but prominent among previously unreported effects were brain morphological abnormalities, seizures, hearing loss, and heart malformations. Our allelic series broadens the phenotypic spectrum of TAF1/MRXS33 intellectual disability syndrome and the range of TAF1 molecular defects in humans. It also illustrates the challenges for determining the pathogenicity of inherited missense variants, particularly for genes mapping to chromosome X.Item De novo and inherited TCF20 pathogenic variants are associated with intellectual disability, dysmorphic features, hypotonia, and neurological impairments with similarities to Smith-Magenis syndrome(BMC, 2019-02-28) Vetrini, Francesco; McKee, Shane; Rosenfeld, Jill A.; Suri, Mohnish; Lewis, Andrea M.; Nugent, Kimberly Margaret; Roeder, Elizabeth; Littlejohn, Rebecca O.; Holder, Sue; Zhu, Wenmiao; Alaimo, Joseph T.; Graham, Brett; Harris, Jill M.; Gibson, James B.; Pastore, Matthew; McBride, Kim L.; Komara, Makanko; Al-Gazali, Lihadh; Al Shamsi, Aisha; Fanning, Elizabeth A.; Wierenga, Klaas J.; Scott, Daryl A.; Ben-Neriah, Ziva; Meiner, Vardiella; Cassuto, Hanoch; Elpeleg, Orly; Holder, J. Lloyd, Jr.; Burrage, Lindsay C.; Seaver, Laurie H.; Van Maldergem, Lionel; Mahida, Sonal; Soul, Janet S.; Marlatt, Margaret; Matyakhina, Ludmila; Vogt, Julie; Gold, June-Anne; Park, Soo-Mi; Varghese, Vinod; Lampe, Anne K.; Kumar, Ajith; Lees, Melissa; Holder-Espinasse, Muriel; McConnell, Vivienne; Bernhard, Birgitta; Blair, Ed; Harrison, Victoria; The DDD study; Muzny, Donna M.; Gibbs, Richard A.; Elsea, Sarah H.; Posey, Jennifer E.; Bi, Weimin; Lalani, Seema; Xia, Fan; Yang, Yaping; Eng, Christine M.; Lupski, James R.; Liu, Pengfei; Medical and Molecular Genetics, School of MedicineBACKGROUND: Neurodevelopmental disorders are genetically and phenotypically heterogeneous encompassing developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASDs), structural brain abnormalities, and neurological manifestations with variants in a large number of genes (hundreds) associated. To date, a few de novo mutations potentially disrupting TCF20 function in patients with ID, ASD, and hypotonia have been reported. TCF20 encodes a transcriptional co-regulator structurally related to RAI1, the dosage-sensitive gene responsible for Smith-Magenis syndrome (deletion/haploinsufficiency) and Potocki-Lupski syndrome (duplication/triplosensitivity). METHODS: Genome-wide analyses by exome sequencing (ES) and chromosomal microarray analysis (CMA) identified individuals with heterozygous, likely damaging, loss-of-function alleles in TCF20. We implemented further molecular and clinical analyses to determine the inheritance of the pathogenic variant alleles and studied the spectrum of phenotypes. RESULTS: We report 25 unique inactivating single nucleotide variants/indels (1 missense, 1 canonical splice-site variant, 18 frameshift, and 5 nonsense) and 4 deletions of TCF20. The pathogenic variants were detected in 32 patients and 4 affected parents from 31 unrelated families. Among cases with available parental samples, the variants were de novo in 20 instances and inherited from 4 symptomatic parents in 5, including in one set of monozygotic twins. Two pathogenic loss-of-function variants were recurrent in unrelated families. Patients presented with a phenotype characterized by developmental delay, intellectual disability, hypotonia, variable dysmorphic features, movement disorders, and sleep disturbances. CONCLUSIONS: TCF20 pathogenic variants are associated with a novel syndrome manifesting clinical characteristics similar to those observed in Smith-Magenis syndrome. Together with previously described cases, the clinical entity of TCF20-associated neurodevelopmental disorders (TAND) emerges from a genotype-driven perspective.Item Phenotypic expansion in DDX3X - a common cause of intellectual disability in females(Wiley, 2018-09-15) Wang, Xia; Posey, Jennifer E.; Rosenfeld, Jill A.; Bacino, Carlos A.; Scaglia, Fernando; Immken, LaDonna; Harris, Jill M.; Hickey, Scott E.; Mosher, Theresa M.; Slavotinek, Anne; Zhang, Jing; Beuten, Joke; Leduc, Magalie S.; He, Weimin; Vetrini, Francesco; Walkiewicz, Magdalena A.; Bi, Weimin; Xiao, Rui; Liu, Pengfei; Shao, Yunru; Gezdirici, Alper; Gulec, Elif Y.; Jiang, Yunyun; Darilek, Sandra A.; Hansen, Adam W.; Khayat, Michael M.; Pehlivan, Davut; Piard, Juliette; Muzny, Donna M.; Hanchard, Neil; Belmont, John W.; Van Maldergem, Lionel; Gibbs, Richard A.; Eldomery, Mohammad K.; Akdemir, Zeynep C.; Adesina, Adekunle M.; Chen, Shan; Lee, Yi-Chien; Lee, Brendan; Lupski, James R.; Eng, Christine M.; Xia, Fan; Yang, Yaping; Graham, Brett H.; Moretti, Paolo; Medical and Molecular Genetics, School of MedicineDe novo variants in DDX3X account for 1-3% of unexplained intellectual disability (ID) cases and are amongst the most common causes of ID especially in females. Forty-seven patients (44 females, 3 males) have been described. We identified 31 additional individuals carrying 29 unique DDX3X variants, including 30 postnatal individuals with complex clinical presentations of developmental delay or ID, and one fetus with abnormal ultrasound findings. Rare or novel phenotypes observed include respiratory problems, congenital heart disease, skeletal muscle mitochondrial DNA depletion, and late-onset neurologic decline. Our findings expand the spectrum of DNA variants and phenotypes associated with DDX3X disorders.Item Phenotypic expansion of POGZ-related intellectual disability syndrome (White-Sutton syndrome)(Wiley, 2020-01) Batzir, Nurit Assia; Posey, Jennifer E.; Song, Xiaofei; Akdemir, Zeynep Coban; Rosenfeld, Jill A.; Brown, Chester W.; Chen, Emily; Holtrop, Shannon G.; Mizerik, Elizabeth; Moreno, Margarita Nieto; Payne, Katelyn; Raas-Rothschild, Annick; Scott, Richard; Vernon, Hilary J.; Zadeh, Neda; Lupski, James R.; Sutton, V. Reid; Neurology, School of MedicineWhite-Sutton syndrome (WHSUS) is a recently-identified genetic disorder resulting from de novo heterozygous pathogenic variants in POGZ. Thus far, over 50 individuals have been reported worldwide, however phenotypic characterization and data regarding the natural history are still incomplete. Here we report the clinical features of 22 individuals with 21 unique loss of function POGZ variants. We observed a broad spectrum of intellectual disability and/or developmental delay with or without autism, and speech delay in all individuals. Other common problems included ocular abnormalities, hearing loss and gait abnormalities. A validated sleep disordered breathing questionnaire identified symptoms of obstructive sleep apnea in 4/12 (33%) individuals. A higher-than-expected proportion of cases also had gastrointestinal phenotypes, both functional and anatomical, as well as genitourinary anomalies. In line with previous publications, we observed an increased body mass index (BMI) z-score compared to the general population (mean 0.59, median 0.9; p 0.0253). Common facial features included microcephaly, broad forehead, midface hypoplasia, triangular mouth, broad nasal root and flat nasal bridge. Analysis of the Baylor Genetics clinical laboratory database revealed that POGZ variants were implicated in approximately 0.14% of cases who underwent clinical exome sequencing for neurological indications with or without involvement of other body systems. This study describes a greater allelic series and expands the phenotypic spectrum of this new syndromic form of intellectual disability and autism.Item Whole-Exome Sequencing in Familial Parkinson Disease(The JAMA Network, 2016-01) Farlow, Janice L.; Robak, Laurie A.; Hetrick, Kurt; Bowling, Kevin; Boerwinkle, Eric; Coban-Akdemir, Zeynep H.; Gambin, Tomasz; Gibbs, Richard A.; Gu, Shen; Jain, Preti; Jankovic, Joseph; Jhangiani, Shalini; Kaw, Kaveeta; Lai, Dongbing; Lin, Hai; Ling, Hua; Liu, Yunlong; Lupski, James R.; Muzny, Donna; Porter, Paula; Pugh, Elizabeth; White, Janson; Doheny, Kimberly; Myers, Richard M.; Shulman, Joshua M.; Foroud, Tatiana; Department of Medical and Molecular Genetics, IU School of MedicineIMPORTANCE: Parkinson disease (PD) is a progressive neurodegenerative disease for which susceptibility is linked to genetic and environmental risk factors. OBJECTIVE: To identify genetic variants contributing to disease risk in familial PD. DESIGN, SETTING, AND PARTICIPANTS: A 2-stage study design that included a discovery cohort of families with PD and a replication cohort of familial probands was used. In the discovery cohort, rare exonic variants that segregated in multiple affected individuals in a family and were predicted to be conserved or damaging were retained. Genes with retained variants were prioritized if expressed in the brain and located within PD-relevant pathways. Genes in which prioritized variants were observed in at least 4 families were selected as candidate genes for replication in the replication cohort. The setting was among individuals with familial PD enrolled from academic movement disorder specialty clinics across the United States. All participants had a family history of PD. MAIN OUTCOMES AND MEASURES: Identification of genes containing rare, likely deleterious, genetic variants in individuals with familial PD using a 2-stage exome sequencing study design. RESULTS: The 93 individuals from 32 families in the discovery cohort (49.5% [46 of 93] female) had a mean (SD) age at onset of 61.8 (10.0) years. The 49 individuals with familial PD in the replication cohort (32.6% [16 of 49] female) had a mean (SD) age at onset of 50.1 (15.7) years. Discovery cohort recruitment dates were 1999 to 2009, and replication cohort recruitment dates were 2003 to 2014. Data analysis dates were 2011 to 2015. Three genes containing a total of 13 rare and potentially damaging variants were prioritized in the discovery cohort. Two of these genes (TNK2 and TNR) also had rare variants that were predicted to be damaging in the replication cohort. All 9 variants identified in the 2 replicated genes in 12 families across the discovery and replication cohorts were confirmed via Sanger sequencing. CONCLUSIONS AND RELEVANCE: TNK2 and TNR harbored rare, likely deleterious, variants in individuals having familial PD, with similar findings in an independent cohort. To our knowledge, these genes have not been previously associated with PD, although they have been linked to critical neuronal functions. Further studies are required to confirm a potential role for these genes in the pathogenesis of PD.