6:162 patients (3.6%) requested AOTT (1 patient conceived spontaneously immediately before AOTT; 1 patient was diagnosed with BRCA1 and BRCA2 gene mutations, and had a family history of several BRCA related cancers, and was therefore advised against AOTT; 1 patient had leukemia-specific gene re-arrangements (IgH and TCRD/A) in the cryopreserved ovarian tissue; 1 patient treated for diffuse natural killer cell lymphoma was under assessment for AOTT at the time of the study). This evidence concerns the gene BRCA1 and leukemia.