Mutations of the Rab27a gene cause Griscelli syndrome type 2 manifesting in partial albinism due to insufficient melanosome transfer from skin melanocytes to keratinocytes and fatal hemophagocytic disorder due to defective lytic granule exocytosis in cytotoxic T lymphocytes (Ménasche et al., 2000). The gene discussed is RAB27A; the disease is Griscelli disease type 2.