MARK2 and melanoma: Copy number in the genome has in general been less systematically explored than sequence variation due to technical constraints,23 as copy-number variation is enriched in areas of low genome mappability.24 However, copy-number variants are known to be prevalent in genes for cell communication and RAS-pathway signaling, including serine threonine kinases and phosphatases,25 and may therefore be highly relevant in the development of melanoma.