DOCK8 deficiency predisposes to virus-related malignancy and is deleted in some cancers, but not markedly in melanoma.21,22 DOCK8 regulates Cdc42 activation especially in immune effector cells—Cdc42 has been implicated in melanoma invasiveness23 and variants in CDC42 have been previously associated with melanoma tumor thickness24 —though our best association P value in the region of that latter gene is 3 × 10−4. This evidence concerns the gene CDC42 and melanoma.