Br J Dermatol  1994 Jul;131(1):72-7 

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

Carr J, Mackie RM.

Department of Dermatology, University of Glasgow, U.K.

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)

PMID: 8043423 [PubMed - indexed for MEDLINE]