The complete inability to sense pain in an otherwise healthy individual is a very rare phenotype. In three consanguineous families from northern Pakistan, we mapped the condition as an autosomal-recessive trait to chromosome 2q24.3. This region contains the gene SCN9A, encoding the α-subunit of the voltage-gated sodium channel, Nav1.7, which is strongly expressed in nociceptive neurons. Sequence analysis of SCN9A in affected individuals revealed three distinct homozygous nonsense mutations (S459X, I767X and W897X). We show that these mutations cause loss of function of Nav1.7 by co-expression of wild-type or mutant human Nav1.7 with sodium channel β1 and β2 subunits in HEK293 cells. In cells expressing mutant Nav1.7, the currents were no greater than background. Our data suggest that SCN9A is an essential and non-redundant requirement for nociception in humans. These findings should stimulate the search for novel analgesics that selectively target this sodium channel subunit.

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We thank the families who participated in this study, A. Boylston for critical advice, and Pfizer, the Wellcome Trust and St John’s College, Cambridge for funding. Author Contributions This study was designed by J.J.C., F.R., E.R., R.W., D.P.M., F.M.G. and C.G.W.; patient identification and phenotype assessment was performed by G.K., H.J., J.M., Y.R., L.A.-G., H.H., E.M.V., S.G. and C.G.W.; DNA extraction, linkage analysis, bioinformatics and sequencing was performed by J.J.C., A.K.N., E.R., K.S. and C.G.W.; cloning was performed by J.J.C.; electrophysiology was performed by F.R. and F.M.G.; and the paper was written by J.J.C., F.R., G.T., J.N.W., F.M.G. and C.G.W.

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Author notes

  1. James J. Cox and Frank Reimann: These authors contributed equally to this work.


  1. Department of Medical Genetics

    • James J. Cox
    • , Adeline K. Nicholas
    • , Gemma Thornton
    •  & C. Geoffrey Woods
  2. Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Wellcome/MRC Building, Addenbrooke’s Hospital, Cambridge, CB2 0XY, UK

    • Frank Reimann
    •  & Fiona M. Gribble
  3. Section of Ophthalmology and Neuroscience Leeds Institute of Molecular Medicine

    • Emma Roberts
    •  & Kelly Springell
  4. Department of Clinical Genetics, St James’s University Hospital, Leeds, LS9 7TF, UK

    • Gulshan Karbani
  5. Gene Tech Lab 146/1, Shadman Jail Road, Lahore, Pakistan

    • Hussain Jafri
  6. Department of Paediatrics, Fatima Jinah Medical College, Lahore, Pakistan

    • Jovaria Mannan
  7. Department of Obstetrics and Gynaecology, King Edward Medical University, Lahore, Pakistan

    • Yasmin Raashid
  8. Department of Paediatrics, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Anin, P O Box 15551, United Arab Emirates

    • Lihadh Al-Gazali
  9. National Center for Diabetes, Endocrinology and Genetics, P O Box 3165/11942, Amman, Jordan

    • Henan Hamamy
  10. IRCCS CSS, San Giovanni Rotondo and CSS Mendel, Rome, I-00168, Italy

    • Enza Maria Valente
  11. Department of Paediatrics, St Luke’s Hospital, Bradford, BD5 0NA, UK

    • Shaun Gorman
  12. Pfizer Global Research and Development, Sandwich Laboratories, Sandwich, CT13 9NJ, UK

    • Richard Williams
    •  & Duncan P. McHale
  13. Molecular Nociception Group, Department of Biology, University College London, London, WC1E 6BT, UK

    • John N. Wood


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Competing interests

The sequence for full-length human SCN9A cloned from fetal brain mRNA is deposited in GenBank under accession number DQ857292. Reprints and permissions information is available at The authors declare no competing financial interests.

Corresponding author

Correspondence to C. Geoffrey Woods.

Supplementary information

  1. Supplementary Information

    This file contains Supplementary Methods discussing cloning methodology used to generate the constructs for this study, Supplementary Figures 1- 2 and Supplementary Tables 1-2. Supplementary Figure 1 shows kinetic properties of whole cell wild-type NaV1.7+NaVβ1+NaVβ2 currents in HEK293 cells. Supplementary Figure 2 shows alignment of the amino acid sequences of the corresponding common splice variants for the human (NP_002968) and mouse Nav1.7 (XP_904764) proteins using the LALIGN program (: = identical amino acid; . = similar amino acid). Supplementary Table 1 shows markers used to search for common haplotype blocks between the three families.Supplementary Table 2 shows primers used to amplify and sequence the coding exons and splice sites of SCN9A (PDF 5083 kb)

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