Cyclic neutropenia transferred from an affected sibling to her unaffected sister by bone marrow transplantation. The donor and recipient cycle nearly synchronously. The family is pedigree number 601 from Horwitz et al,⁴³  which segregates the ELA2 +5 G>A mutation in intron 4. The unaffected sister (who lacked the family's ELA2 mutation) underwent bone marrow transplantation for the treatment of acute lymphoblastic leukemia; her affected sister (later found to have an ELA2 mutation) was HLA matched and served as the donor. Adapted from Krance et al  with permission.