Thirty-nine multiple family cases have been recorded with 77 pairs and 91 involved relatives having leukemia or lymphoma. Thirty-two of the 39 families involved a close genetic relationship between affected siblings or parent-child pairs. The multiple family case members died earlier than single family case members on a comparative study. This suggests that genetic factors are of importance in the etiology of these malignant hematologic proliferations.
Rigby PG, Pratt PT, Rosenlof RC, Lemon HM. Genetic Relationships in Familial Leukemia and Lymphoma. Arch Intern Med. 1968;121(1):67-70. doi:10.1001/archinte.1968.03640010069011