ROBO4 variants predispose individuals to bicuspid aortic valve and thoracic aortic aneurysm

Russell A. Gould, Hamza Aziz, Courtney E. Woods, Manuel Alejandro Seman-Senderos, Elizabeth Sparks, Christoph Preuss, Florian Wünnemann, Djahida Bedja, Cassandra R. Moats, Sarah A. McClymont, Rebecca Rose, Nara Sobreira, Hua Ling, Gretchen MacCarrick, Ajay Anand Kumar, Ilse Luyckx, Elyssa Cannaerts, Aline Verstraeten, Hanna M. Björk, Ann-Cathrin Lehsau, Vinod Jaskula-Ranga, Henrik Lauridsen, Asad A. Shah, Christopher L. Bennett, Patrick T. Ellinor, Honghuang Lin, Eric M. Isselbacher, Christian Lacks Lino Cardenas, Jonathan T. Butcher, G. Chad Hughes, Mark E. Lindsay, Baylor-Hopkins Center for Mendelian Genomics, MIBAVA Leducq Consortium, Luc Mertens, Anders Franco-Cereceda, Judith M. A. Verhagen, Marja Wessels, Salah A. Mohamed, Per Eriksson, Seema Mital, Lut Van Laer, Bart L. Loeys, Gregor Andelfinger, Andrew S. McCallion & Harry C. Dietz

Nature Genetics 2018. (19 November 2018).

Bicuspid aortic valve (BAV) is a common congenital heart defect (population incidence, 1–2%) that frequently presents with ascending aortic aneurysm (AscAA). BAV/AscAA shows autosomal dominant inheritance with incomplete penetrance and male predominance. Causative gene mutations (for example, NOTCH1, SMAD6) are known for ≤1% of nonsyndromic BAV cases with and without AscAA5–8, impeding mechanistic insight and development of therapeutic strategies. Here, we report the identification of variants in ROBO4 (which encodes a factor known to contribute to endothelial performance) that segregate with disease in two families. Targeted sequencing of ROBO4 showed enrichment for rare variants in BAV/AscAA probands compared with controls. Targeted silencing of ROBO4 or mutant ROBO4 expression in endothelial cell lines results in impaired barrier function and a synthetic repertoire suggestive of endothelial-to-mesenchymal transition. This is consistent with BAV/AscAA-associated findings in patients and in animal models deficient for ROBO4. These data identify a novel endothelial etiology for this common human disease phenotype.