However, a significant quantity of donor DNA would be required, given that the recipient’s DNA would contain 50% variant and 50% wild-type sequence at that locus; however, if the patient presented with bone marrow failure due to the presence of a heterozygous FANCA variant and is leukopenic, a much lower quantity of donor DNA would be required to decrease the variant from the expected 50%. The gene discussed is FANCA; the disease is Bone marrow hypocellularity.