Identification of 4 novel human ocular coloboma genes ANK3, BMPR1B, PDGFRA, and CDH4 through evolutionary conserved vertebrate gene analysis
Nicholas Owen, Maria Toms, Rodrigo Young, Jonathan Eintracht, Hajrah Sarkar, Brian P. Brooks, Mariya Moosajee, John C. Ambrose, E. L. Baple, Marta Bleda, F. Boardman-Pretty, J. M. Boissiere, C. R. Boustred, Mark J. Caulfield, G. C. Chan, C. E. H. Craig, Louise C. Daugherty, Burca A. de, A. Devereau, Greg Elgar, Rebecca E. Foulger, Tom Fowler, Pedro Furió‐Tarí, J.M. Hackett, Dina Halai, John E. Holman, Tim Hubbard, R. Jackson, Dalia Kasperavičiūtė, Melis Kayikci, L. Lahnstein, Katy L. Lawson, S. E. A. Leigh, I. U. S. Leong, Fabrice Lopez, F. Maleady-Crowe, Joanne Mason, Ellen M. McDonagh, Loukas Moutsianas, M. Mueller, Nirupa Murugaesu, Anna C. Need, Chris A. Odhams, Christine Patch, D. Perez-Gil, Dimitris Polychronopoulos, J. Pullinger, T. Rahim, Álvaro Rendón, Pablo Riesgo-Ferreiro, T. Rogers, Mina Ryten, K. Savage, K. Sawant, Roy Scott, Afshan Siddiq, A. Sieghart, Damian Smedley, Kath Smith, Alona Sosinsky, W. Spooner, Hallam Stevens, A. Stuckey, Răzvan Sultana, Elizabeth R. Thomas, Samuel Thompson, Carolyn Tregidgo, Arianna Tucci, Emily Walsh, Scott Watters, M. J. Welland, E. G. Williams, Katarzyna Witkowska, S. M. Wood, Magdalena Zarowiecki
Abstract
PURPOSE: Ocular coloboma arises from genetic or environmental perturbations that inhibit optic fissure (OF) fusion during early eye development. Despite high genetic heterogeneity, 70% to 85% of patients remain molecularly undiagnosed. In this study, we have identified new potential causative genes using cross-species comparative meta-analysis. METHODS: Evolutionarily conserved differentially expressed genes were identified through in silico analysis, with in situ hybridization, gene knockdown, and rescue performed to confirm spatiotemporal gene expression and phenotype. Interrogation of the 100,000 Genomes Project for putative pathogenic variants was performed. RESULTS: Nine conserved differentially expressed genes between zebrafish and mouse were identified. Expression of zebrafish ank3a, bmpr1ba/b, cdh4, and pdgfaa was localized to the OF, periocular mesenchyme cells, or ciliary marginal zone, regions traversed by the OF. Knockdown of ank3, bmpr1b, and pdgfaa revealed a coloboma and/or microphthalmia phenotype. Novel pathogenic variants in ANK3, BMPR1B, PDGFRA, and CDH4 were identified in 8 unrelated coloboma families. We showed BMPR1B rescued the knockdown phenotype but variant messenger RNAs failed, providing evidence of pathogenicity. CONCLUSION: We show the utility of cross-species meta-analysis to identify several novel coloboma disease-causing genes. There is a potential to increase the diagnostic yield for new and unsolved patients while adding to our understanding of the genetic basis of OF morphogenesis.