Genetics and Neurodevelopmental Disorders (16)
Neuroscience and Neuropharmacology Research (14)
Epilepsy research and treatment (11)
Ion channel regulation and function (10)
Neurogenesis and neuroplasticity mechanisms (8)
Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus •
The SCN9A gene codes for the sodium voltage-gated channel NaV 1.7. Gain of function mutations cause pain disorders such as primary erythromelalgia, paroxysmal extreme pain disorder, and small fiber neuropathy. Loss of function mutations lead to congenital insensitivity to pain. We report the case of a 6-year-old girl with a SCN9A mutation who presented with both gain of function and loss of function phenotypes, including congenital corneal anesthesia.
Meijer IA, Vanasse M, Nizard S, Robitaille Y, Rossignol E
Muscle & nerve •
Erythromelalgia due to heterozygous gain-of-function SCN9A mutations usually presents as a pure sensory-autonomic disorder characterized by recurrent episodes of burning pain and redness of the extremities. We describe a patient with an unusual phenotypic presentation of gross motor delay, childhood-onset erythromelalgia, extreme visceral pain episodes, hypesthesia, and self-mutilation. The investigation of the patient's motor delay included various biochemical analyses, a comparative genomic hybridization array (CGH), electromyogram (EMG), and muscle biopsy. Once erythromelalgia was suspected clinically, the SCN9A gene was sequenced. The EMG, CGH, and biochemical tests were negative. The biopsy showed an axonal neuropathy and neurogenic atrophy. Sequencing of SCN9A revealed a heterozygous missense mutation in exon 7; p.I234T. This is a case of global motor delay and erythromelalgia associated with SCN9A. The motor delay may be attributed to the extreme pain episodes or to a developmental perturbation of proprioceptive inputs.