Original ArticlesPhenotypic variability in Muenke syndrome—observations from five Danish familiesÖwall, Louisea; Kreiborg, Svena,,b; Dunø, Mortenc; Hermann, Nuno V.a,,b; Darvann, Tron A.a,,d; Hove, Hannee,,fAuthor Information a3D Craniofacial Image Research Laboratory (School of Dentistry, University of Copenhagen; Centre of Head and Orthopedics, Copenhagen University Hospital Rigshospitalet; and Department of Applied Mathematics and Computer Science, Technical University of Denmark) bDepartment of Paediatric Dentistry and Clinical Genetics, School of Dentistry, Faculty of Health and Medical Science, University of Copenhagen cCentre for Rare Diseases, Department of Clinical Genetics dDepartment of Oral and Maxillofacial Surgery eCentre for Rare Diseases, Department of Paediatrics fThe RAREDIS Database, Centre for Rare Diseases, Department of Paediatrics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark Received 22 June 2019 Accepted 20 August 2019 Correspondence to Louise Öwall, MD, 3D-Lab, School of Dentistry, University of Copenhagen, Nørre Allé 20, DK-2200, Copenhagen, Denmark, Tel: +45 40828530; fax: +45 35326505; e-mail: firstname.lastname@example.org Clinical Dysmorphology: January 2020 - Volume 29 - Issue 1 - p 1-9 doi: 10.1097/MCD.0000000000000300 Buy Erratum Metrics Abstract Muenke syndrome is a craniosynostosis syndrome associated with the p.Pro250Arg mutation in FGFR3. An increasing number of individuals with this mutation are reported to not have craniosynostosis. The purpose of this report is to increase awareness of the high phenotypic variability seen in Muenke syndrome. DNA testing for the p.Pro250Arg mutation is routinely performed in Denmark, in children presenting with isolated coronal synostosis. Verified diagnosis entails detailed family history, drawing of family pedigree, DNA testing of the parents, genetic counseling, skull radiographs, clinical photographs, and follow-up. Sixteen individuals from 5 Danish families with Muenke syndrome are presented. Large phenotypic variation was seen both within and across families. The most striking observations were that 6/16 (38%) cases did not have craniosynostosis and one individual presented with a normal phenotype. In addition, 3 unrelated cases had incomplete cleft palate, submucous cleft palate, and bifid uvula, respectively. There is strong evidence for reduced penetrance of the craniosynostosis trait in Muenke syndrome. We argue that many studies on Muenke syndrome have been influenced by ascertainment bias in regard to craniosynostosis. In addition, it is suggested that oral clefting might be part of the clinical spectrum seen in Muenke syndrome. Erratum In the captions of Figs. 1, 3, and 5 in this article by Öwall (2020), ‘□ indicates UCS’ should be changed to ‘◐ indicates UCS’. Clinical Dysmorphology. 29(2):121, April 2020. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.