Nav1.7 Congenital Insensitivity to Pain is an autosomal recessive disorder and was first reported to map to a region on chromosome 2 by autozygosity mapping in three consanguineous families from northern Pakistan. Candidate gene analysis identified SCN9A. The loss of function mutations in SCN9A are typically nonsense, small out-of-frame deletions or duplications, and splice-site mutations although missense mutations in critical residues have also been reported. Unless previously reported, missense mutations must be characterized by patch clamping studies to determine whether biophysical properties of the channel are changed, before categorising as pathogenic.
Whole gene deletions have been seen, but to date no re-arrangements or intragenic deletions or duplications are reported.