Aplastic anemia (AA) is a rare disease in which the reduction of the circulating blood cells results from damage to the stem cell pool in bone marrow. Most cases of acquired aplastic anemia are the consequence of an immune-mediated destruction of hematopoiesis. Autoreactive cytotoxic T cells play a key role in the pathogenesis of AA by myelosuppressive cytokines including interferon-gamma. It has been reported that polymorphisms in IFNG are related to AA. A minority of patients with AA has heterozygous mutations in genes encoding the telomerase components TERT or TERC. Immunosuppressive therapy (IST) is one of the main treatment modalities for AA, although most patients with telomerase mutations do not respond adequately to IST.