RAB27A and Griscelli disease: Mutations in the gene encoding for Rab27a result in the Griscelli Syndrome Type 2 (GS2), an autosomal recessive pigmentation disorder that is associated with severe immunological defects, caused by impaired function of neutrophil and natural killer cells as well as by malfunctioning cytotoxic T-lymphocytes [12,13,14,15].