Familial predisposition to hematological malignancies has been recognized. Some of these malignancies are part of a well-characterized familial cancer predisposition syndrome, while others are independent of cancer predisposition, and demonstrate unique familial leukemia/lymphoma syndromes. Primary immunodeficiency is also strongly associated with the development of lymphoid malignancy. Primary immunodeficiency and leukemia/lymphoma are based on the same concept, which involves differentiation blockage. Bone marrow failure syndrome is also known to be associated with susceptibility to hematological malignancy development. Bone marrow failure syndrome exhibiting myeloid differentiation is also characterized as an aspect of primary immunodeficiency. Recent progress in genome wide association studies (GWAS) identified several single nucleotide polymorphisms (SNP) associated with leukemia/lymphoma development. Some of these genes were found to be functionally related to hematological malignancies. These discoveries are contributing to elucidation of the genetic background of leukemia/lymphoma development.