HUMAN MUTATION Mutation in Brief 31: E1670-E1686 (2010) Online MUTATION IN BRIEF Congenital Insensitivity to Pain: Novel SCN9A Missense and In-frame Deletion Mutations James J. Cox 1*, Jony Sheynin 2,3*, Zamir Shorer 4*, Frank Reimann 5*, Adeline K. Nicholas 1, Lorena Zubovic6, Marco Baralle 6, Elizabeth Wraige 7, Esther Manor 2,8, Jacov Levy 4, C. Geoffery Woods 1*#, and Ruti Parvari 2,3*# 1 Department of Medical Genetics, University of Cambridge, UK; 2 Department of Virology and Developmental Genetics, Faculty of Health Sciences, and 3National Institute of Biotechnology in the Negev, Ben Gurion University of the Negev, Israel; 4 Division of Pediatrics, Soroka Medical Center and Faculty of Health Sciences, Ben Gurion University of the Negev, Israel;5 Department of Clinical Biochemistry, University of Cambridge, UK; 6 International Centre for Genetic Engineering and Biotechnology, Trieste, Italy; 7 Guy’s and St Thomas’ NHS Foundation Trust, London, UK; 8 Institute of Genetics, Soroka Medical Center and Faculty of Health Sciences, Beer Sheva, Israel. * These authors equally contributed to this work # Correspondence to Prof. Parvari and Dr. Woods. RP: Ben Gurion University of the Negev, Beer Sheva 84105, Israel; Tel.: 972 8 6479967; FAX.: 972 8 6276215; E-mail: ruthi@bgu.ac.il; CGW: Cambridge Institute for Medical Research, Cambridge, CB2 0XY, UK; Tel.: +44 1223 767811; FAX.: +44 1223 331206; E-mail: cw347@cam.ac.uk Communicated by Claude Ferec HUMAN MUTATION OFFICIAL JOURNAL www.hgvs.org ABSTRACT: SCN9A encodes the voltage-gated sodium channel Nav1.7, a protein highly expressed in pain-sensing neurons. Mutations in SCN9A cause three human pain disorders: bi-allelic loss of function mutations result in Channelopathy-associated Insensitivity to Pain (CIP), whereas activating mutations cause severe episodic pain in Paroxysmal Extreme Pain Disorder (PEPD) and Primary Erythermalgia (PE). To date, all mutations in SCN9A that cause a complete inability to experience pain are protein truncating and presumably lead to no protein being produced. Here, we describe the identification and functional characterization of two novel non-truncating mutations in families with CIP: a homozygously-inherited missense mutation found in a consanguineous Israeli Bedouin family (Nav1.7-R896Q) and a five amino acid in-frame deletion found in a sporadic compound heterozygote (Nav1.7-ΔR1370-L1374). Both of these mutations map to the pore region of the Nav1.7 sodium channel. Using transient transfection of PC12 cells we found a significant reduction in membrane localization of the mutant protein compared to the wild type. Furthermore, voltage clamp experiments of mutant-transfected HEK293 cells show a complete loss of function of the sodium channel, consistent with the absence of pain phenotype. In summary, this study has identified critical amino acids needed for the normal subcellular localization and function of Nav1.7. ©2010 Wiley-Liss, Inc. KEY WORDS: SCN9A; Sodium channel Nav1.7; congenital insensitivity to pain; channelopathy INTRODUCTION Pain is one of the most pervasive symptoms in clinical medicine; it occurs in a multitude of clinical conditions and is encountered by clinicians in every subspecialty. Yet treatment of pain remains challenging despite many Received 3 December 2009; accepted revised manuscript 29 June 2010. © 2010 WILEY-LISS, INC. DOI:10.1002/humu.21325