Clinical features
Mutations in the SCN9A gene may cause an inability to feel any type of pain at any time in an affected person’s life. Hence, patients are at significant risk of injuries, mainly self-inflicted injuries that go unnoticed, and their symptoms may not been taken seriously by clinicians. Patients with mutation SCN9A-related disorder may also suffer from an inability to smell, which is often unnoticed and is relatively unimportant.
Prevalence
Mutations in the SCN9A gene are very rare. The prevalence is assumed to be approximately 1 in a million.
Inheritance
The inheritance pattern is autosomal recessive. This means that if both parents carry a mutation involving this gene (usually without displaying the disease), there is a greater chance that their children are going to inherit the mutations from both parents and display the disease. Parents who already have and affected child have a chance of 1 in 4 of having another affected child. In this, both sexes are equally affected.