REPORT BMP9 Mutations Cause a Vascular-Anomaly Syndrome with Phenotypic Overlap with Hereditary Hemorrhagic Telangiectasia Whitney L. Wooderchak-Donahue, 1 Jamie McDonald, 2 Brendan O’Fallon, 1 Paul D. Upton, 3 Wei Li, 3 Beth L. Roman, 4 Sarah Young, 4 Parker Plant, 1 Gyula T. Fu ¨lo ¨p, 5,6 Carmen Langa, 5,6 Nicholas W. Morrell, 3 Luisa M. Botella, 5,6 Carmelo Bernabeu, 5,6 David A. Stevenson, 7 James R. Runo, 8 and Pinar Bayrak-Toydemir 1,2, * Hereditary hemorrhagic telangiectasia (HHT), the most common inherited vascular disorder, is caused by mutations in genes involved in the transforming growth factor beta (TGF-b) signaling pathway (ENG, ACVRL1, and SMAD4). Yet, approximately 15% of individuals with clinical features of HHT do not have mutations in these genes, suggesting that there are undiscovered mutations in other genes for HHT and possibly vascular disorders with overlapping phenotypes. The genetic etiology for 191 unrelated individuals clinically sus- pected to have HHT was investigated with the use of exome and Sanger sequencing; these individuals had no mutations in ENG, ACVRL1, and SMAD4. Mutations in BMP9 (also known as GDF2) were identified in three unrelated probands. These three individuals had epistaxis and dermal lesions that were described as telangiectases but whose location and appearance resembled lesions described in some individuals with RASA1-related disorders (capillary malformation-arteriovenous malformation syndrome). Analyses of the variant proteins suggested that mutations negatively affect protein processing and/or function, and a bmp9-deficient zebrafish model demonstrated that BMP9 is involved in angiogenesis. These data confirm a genetic cause of a vascular-anomaly syndrome that has phenotypic overlap with HHT. Hereditary hemorrhagic telangiectasia (HHT [MIM 187300 and 600376]) is an autosomal-dominantly inherited vascular-malformation syndrome characterized by telangiectases and arteriovenous malformations (AVMs) and has an incidence of 1 in 10,000 individ- uals. 1 Hallmark features are recurrent epistaxis due to telangiectases of the nasal mucosa; telangiectases on the lips, hands and oral mucosa; solid-organ AVMs, parti- cularly of the lungs, liver, and brain; and a family history of the same. Presentation with three of these criteria is considered diagnostic for HHT. 2 The dermal telangiecta- ses are typically pinpoint to pinhead sized, very specif- ically concentrated on the hands, face and lips, and not diffuse. Telangiectases on the limbs and trunk are not characteristic. Currently, all known genetic defects that cause HHT are found within the transforming growth factor beta (TGF-b) signaling pathway. Mutations in endoglin (ENG [MIM 131195]), activin A receptor type II-like 1 (ACVRL1, also known as ALK1 [MIM 601284]), and SMAD4 (MIM 600993) cause HHT type 1, HHT type 2, and the combined juvenile polyposis (JP) and HHT (JP-HHT) syndrome, respectively. 3–5 Approximately 15% of individuals identi- fied clinically as having HHT currently have no known ge- netic cause, 6 suggesting that there are undiscovered genes associated with HHT. Dermal telangiectases and cerebral AVMs are also fea- tures of capillary-malformation (CM)-AVM syndrome (CM-AVM [MIM 608354]), caused by mutations in RASA1 (MIM 139150). 7–10 Recurrent nosebleeds have not been described, and the typical dermal telangiectases generally differ from HHT in location and appearance. The telangiec- tases seen in CM-AVM include both the small punctate lesions that characterize HHT and the larger telangiectases referred to as CMs. The punctate telangiectases in CM- AVM are more commonly diffuse and tend to cluster in a region of the trunk or limbs (M. Vikkula, personal commu- nication). We first performed exome sequencing in 38 unrelated individuals reported to have HHT 2 (by physicians who had ordered HHT genetic testing) but in whom no muta- tion had been identified in ENG, ACVRL1 or SMAD4. Informed consent was obtained from all individuals (approved by the institutional review board [00028740] at the University of Utah). Samples were enriched with the use of exome-targeted biotinylated RNA baits (SureSe- lect 50 Mb) and sequenced with 23 100 bp paired-end reads (HiSeq2000, Illumina). The Burrows-Wheeler Aligner (0.5.9) 11 and the Genome Analysis Toolkit (v.1.6) 12 were used for data analysis. To reduce the number of false-posi- tive variant calls, we used raw variant sets as input to a Variant Quality Score Recalibration procedure, and we 1 Associated Regional and University Pathologists Institute for Clinical and Experimental Pathology, Salt Lake City, UT 84108, USA; 2 Department of Pathol- ogy, University of Utah, Salt Lake City, UT 84108, USA; 3 Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK; 4 Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; 5 Centro de Investigaciones Biolo ´ gicas, Consejo Superior de Investigaciones Cientı ´ficas, Madrid 28040, Spain; 6 Centro de Investigacio ´n Biome ´dica en Red de Enfermedades Raras, Madrid 28040, Spain; 7 Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, UT 84108, USA; 8 Department of Med- icine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA *Correspondence: pinar.bayrak-toydemir@aruplab.com http://dx.doi.org/10.1016/j.ajhg.2013.07.004. Ó2013 by The American Society of Human Genetics. All rights reserved. 530 The American Journal of Human Genetics 93, 530–537, September 5, 2013