Some of the lysosomal storage disorders, e.g., Chediak-Higashi syndrome or Hermasky-Pudlak syndrome type 2, are characterized by defective NK cell function and immunodeficiency (Table 1), but the function of the genes mutated in these diseases (LYST and AP3BP1) has not been fully elucidated in NK cell biology. The gene discussed is LYST; the disease is lysosomal storage disease.