Donor-derived 47, XXY in an unrelated cord blood transplant recipient

A 65-year-old Japanese male with therapy-related myelodysplastic syndrome was admitted for unrelated cord blood transplantation. A cord blood unit from a male donor was obtained from the Japan Cord Blood Bank Network. The patient then received a conditioning regimen consisting of fludarabine, intravenous busulfan, and total body irradiation. Successful engraftment was obtained. The bone marrow examination on day 28 revealed trilineage engraftment, and chimerism analysis by variable number of tandem repeat polymerase chain reaction confirmed complete donor chimerism. At that time, conventional cytogenetics of the bone marrow aspirate showed 20 out of 20 metaphases with the 47, XXY karyotype characteristic of Klinefelter syndrome. Klinefelter syndrome is the most common genetic cause of human male infertility with a reported prevalence of 0.1-0.2% in the general population. In Japan Cord Blood Bank Network, there is no informed consent from parents about the possibility that post-unrelated cord blood transplantation patient evaluation may reveal donor-origin inherited diseases including cytogenetic abnormality. It is desirable to have opportunities in Japan discussing whether parents will be notified of the possibility that post-unrelated cord blood transplantation evaluation may reveal donor-derived illness incidentally.