The non-synonymous MTAP SNP rs7023954 (c.G166A, p.Val56Ile, GenBank accession numbers XM 027613 and NM 00D2451) was genotyped by Sanger sequencing of exon 3, which had been PCR amplified from reverse transcribed MTAP transcripts isolated from normal skin as well as primary and metastatic melanoma cell lines and tissues (Fig 1, S1 Table). The gene discussed is MTAP; the disease is metastatic melanoma.