title: Hereditary sensory and autonomic neuropathy type IID caused by an SCN9A mutation.
abstract: OBJECTIVE
  To identify the clinical features of Japanese patients with suspected hereditary sensory and autonomic neuropathy (HSAN) on the basis of genetic diagnoses.
  
  
  METHODS
  On the basis of clinical, in vivo electrophysiologic, and pathologic findings, 9 Japanese patients with sensory and autonomic nervous dysfunctions were selected. Eleven known HSAN disease-causing genes and 5 related genes were screened using a next-generation sequencer.
  
  
  RESULTS
  A homozygous mutation, c.3993delGinsTT, was identified in exon 22 of SCN9A from 2 patients/families. The clinical phenotype was characterized by adolescent or congenital onset with loss of pain and temperature sensation, autonomic nervous dysfunctions, hearing loss, and hyposmia. Subsequently, this mutation was discovered in one of patient 1's sisters, who also exhibited sensory and autonomic nervous system dysfunctions, with recurrent fractures being the most predominant feature. Nerve conduction studies revealed definite asymmetric sensory nerve involvement in patient 1. In addition, sural nerve pathologic findings showed loss of large myelinated fibers in patient 1, whereas the younger patient showed normal sural nerve pathology.
  
  
  CONCLUSIONS
  We identified a novel homozygous mutation in SCN9A from 2 Japanese families with autosomal recessive HSAN. This loss-of-function SCN9A mutation results in disturbances in the sensory, olfactory, and autonomic nervous systems. We propose that SCN9A mutation results in the new entity of HSAN type IID, with additional symptoms including hyposmia, hearing loss, bone dysplasia, and hypogeusia.
authors.affiliation: Department of Neurology and Geriatrics, Kagoshima University, Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Junhui
authors.initials: J
authors.lastname: Yuan
authors.forename: Eiji
authors.initials: E
authors.lastname: Matsuura
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Higuchi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hashiguchi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Nakamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nozuma
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sakiyama
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoshimura
authors.forename: Shuji
authors.initials: S
authors.lastname: Izumo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takashima
mesh_terms: D000328:Adult; D044466:Asian People; D001706:Biopsy; D005192:Family Health; D005260:Female; D005808:Genes, Recessive; D009477:Hereditary Sensory and Autonomic Neuropathies / Q000235:genetics* / Q000473:pathology*; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D062556:NAV1.7 Voltage-Gated Sodium Channel / Q000235:genetics*; D009431:Neural Conduction / Q000502:physiology; D013497:Sural Nerve / Q000473:pathology / Q000503:physiopathology
chemical_list: D062556:NAV1.7 Voltage-Gated Sodium Channel; C486866:SCN9A protein, human