Point mutations in the N-ras oncogene in malignant melanoma and congenital naevi

Br J Dermatol. 1994 Jul;131(1):72-7. doi: 10.1111/j.1365-2133.1994.tb08460.x.


DNA from formalin-fixed and paraffin-processed samples from 100 melanocytic lesions (39 malignant melanomas, 18 cases of dysplastic naevi, and 43 congenital naevi) was extracted, and the sequences around codons 12/13 and 61 of the N-ras oncogene were amplified using the polymerase chain reaction. The amplified product was then analysed both by dot-blotting and by direct sequencing for point mutations. By the dot-blotting technique, mutations were seen in 18 of 100 lesions. These were in one of five distant metastases (20%), in one of three nodal metastases (33%), in four of 31 (13%) primary melanomas, in none of 18 dysplastic naevi, and in 12 of 43 (28%) congenital naevi, all at codon 61. On direct sequencing, nine of 18 mutations were confirmed, in two of 31 (6%) primary tumours, one distant metastasis, and six of 43 (14%) congenital naevi. Of the 23 superficial spreading melanomas examined, eight were on sun-exposed skin. A superficial spreading melanoma, in which the N-ras mutation at codon 61 was confirmed, was on non-exposed skin, and an unconfirmed mutation was from an exposed site. One of three nodular melanomas with a confirmed mutation was on a light-exposed site, and the other two nodular melanomas were from non-exposed areas. All four lentigo maligna melanomas were from exposed sites, and one of these had an unconfirmed mutation. The only acral lentiginous melanoma, which had no mutation, was from a sun-exposed area.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Base Sequence
  • Codon / genetics*
  • DNA Primers / genetics
  • Dysplastic Nevus Syndrome / genetics
  • Female
  • Genes, ras / genetics*
  • Genetic Techniques
  • Humans
  • Male
  • Melanoma / genetics*
  • Middle Aged
  • Molecular Sequence Data
  • Nevus / genetics*
  • Nevus, Pigmented / congenital
  • Nevus, Pigmented / genetics
  • Point Mutation / genetics*
  • Polymerase Chain Reaction
  • Skin Neoplasms / congenital
  • Skin Neoplasms / genetics*


  • Codon
  • DNA Primers