A Novel Nonsense Mutation in SCN9A in a Moroccan Child With Congenital Insensitivity to Pain

BACKGROUND: Congenital insensitivity to pain is a rare autosomal recessive disease. Individuals who are diagnosed with congenital insensitivity to pain usually present severely impaired pain perception, and in some cases, they also manifest a decreased sense of smell (anosmia). This disease is caused by loss of function mutations affecting the SCN9A gene, which encodes the voltage-gated sodium channel Nav1.7. It is noteworthy that nearly every mutation linking this particular channel to congenital insensitivity to pain has been demonstrated to underlie the translation of a truncated protein. METHODS: Complete sequencing of the SCN9A gene in a Moroccan 3-year-old child with congenital insensitivity to pain. RESULT: We identified a homozygous nonsense mutation (c.4795C>T) in exon 27, that results in codon stop in the amino acid (p.R1599X). CONCLUSION: In this report we present a previously unreported homozygous nonsense mutation present in a consanguineous Moroccan congenital insensitivity to pain patient with anosmia. The identification of this mutation extends the spectrum of mutations affecting the Nav1.7 channel, and it confirms earlier studies that established Nav1.7 roles in nociception and the sense of smell.