Lack of SF3B1 R625 mutations in cutaneous melanoma

Melanoma is a deadly disease affecting people worldwide. Genetic studies have identified different melanoma subtypes characterized by specific recurrently mutated genes and led to the successful clinical introduction of targeted therapies. Hotspot mutations in SF3B1 were recently reported in uveal melanoma. Our aim was to see if these mutations also occur in cutaneous melanoma. We analyzed a cohort of 85 cutaneous melanoma including 22 superficial spreading, 24 acral-lentiginous, 36 nodular, and 3 lentigo-maligna melanomas. Exon 14 of SF3B1, containing the site of recurrent mutations described in uveal melanoma, was sequenced in all samples. Additionally, NRAS exon 1 and 2 and BRAF exon 15 were sequenced in all, KIT exons 9, 11, 13, 17, and 18 in 30 samples. High numbers of BRAF and NRAS mutations were identified with frequencies varying according to melanoma subtype. None of the samples were found to harbor a SF3B1 mutation. We conclude that recurrent mutations in codon 625 of SF3B1 as reported in uveal melanoma are not present in most types of cutaneous melanoma. This highlights the genetic differences between cutaneous and uveal melanoma and the need for subtype specific therapeutic approaches.