Detection of a change in chromosomal copy number for distinguishing melanocytes nevi from melanoma

摘要

The present invention provides for methods of distinguishing melanocytic nevi, such as Spitz nevi, from malignant melanoma. The methods comprise contacting a nucleic acid sample from a patient with a probe which binds selectively to a target polynucleotide sequence on a chromosomal region such as 11p, which is usually amplified in Spitz nevi. The nucleic acid sample is typically from skin tumor cells located within a tumor lesion on the skin of the patient. Using another probe which binds selectively to a chromosomal region such as 1q, 6p, 7p, 9p, or 10q, which usually show altered copy number in melanoma, the method can determine that those tumor cells with no changes in copy number of 1q, 6p, 7p, 9p, or 10q, are not melanoma cells but rather Spitz nevus cells. The finding of amplifications of chromosome 11p, particularly the presence of an 11p isochromosome would be an additional indication of Spitz nevus. An increase in copy number of chromosome 11p can also be determined by detecting the presence of an amplification of the H-RAS gene. The amplified gene can be normal or can be a mutated H-RAS gene.