title: NRAS mutations in primary and metastatic melanomas of Japanese patients.
abstract: BACKGROUND
  Characterization of the MAPK signaling pathway in melanoma has led to the development of MEK inhibitors for the treatment of NRAS-mutated melanoma. The success of molecular-targeted therapies underscores the need to identify mutations in target genes. Most of the current data on genetic mutations have been obtained from Caucasian melanoma patients, and screenings of Asian populations are limited.
  
  
  OBJECTIVE
  The aim of the present study was to examine NRAS mutations in primary and metastatic lesions of Japanese melanoma patients.
  
  
  METHODS
  Clinical melanoma specimens were collected from 127 Japanese patients, including primary (n = 67), metastatic (n = 25) and paired primary and metastatic lesions (n = 35). NRAS mutations in exons 1 and 2 were assessed by polymerase chain reaction and Sanger sequencing.
  
  
  RESULTS
  The incidence of NRAS mutations was 7.1 %. NRAS (Q61) was the predominant genetic alteration (77.8 %). NRAS mutations were most frequently detected in acral melanomas (9.3 %), followed by melanomas without chronic sun-induced damage (7.0 %) and mucosal melanomas (4.8 %), and were not detected in melanomas with chronic sun-induced damage. In addition, NRAS mutations were more prevalent in the extremities than in other sites. The NRAS sequence in metastatic lesions did not match that of the primary tumor in one case.
  
  
  CONCLUSIONS
  The frequency of NRAS mutations is lower in the Asian population than in Caucasian patients. The observed heterogeneity of melanoma suggests that genotyping of both primary and metastatic lesions is important to identify candidate patients for molecular-targeted therapies.
authors.affiliation: Department of Dermatology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Uhara
authors.forename: Atsuko
authors.initials: A
authors.lastname: Ashida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Koga
authors.forename: Eisaku
authors.initials: E
authors.lastname: Ogawa
authors.forename: Aya
authors.initials: A
authors.lastname: Uchiyama
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Uchiyama
authors.forename: Koichi
authors.initials: K
authors.lastname: Hayashi
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kiniwa
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Okuyama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics; D005091:Exons; D005260:Female; D020558:GTP Phosphohydrolases / Q000235:genetics*; D006801:Humans; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology; D044465:White People / Q000235:genetics
chemical_list: D008565:Membrane Proteins; D020558:GTP Phosphohydrolases; C579846:NRAS protein, human