Successful outcome with day 4 embryo transfer after preimplantation diagnosis for genetically transmitted diseases

Preimplantation genetic diagnosis was performed in 61 day 3 embryosobtained by in-vitro fertilization from seven patient carriers ofhaemophilia, Marfan's syndrome, Bloch-Sulzemberg syndrome (incontinentiapigmentosa) or X chromosome-linked immune deficiency, retinitis pigmentosa,and FG syndrome, which is characterized by mental retardation andhypotonia. After multiplex polymerase chain reaction, 16 embryos werediagnosed as being unaffected, and these were transferred to the uterus onthe following day (day 4). Of these embryos, six (37.5%) implanted,resulting in the delivery of a singleton and a twin pregnancy, a latesecond trimester miscarriage (twins at week 20) and a first trimestermiscarriage at week 8. All the diagnoses were confirmed by amniocentesis.We report for the first time a late day 4 transfer of biopsied humanembryos undergoing preimplantation genetic diagnosis. This transferschedule allows an extra day to perform genetic analyses on singleblastomeres and to monitor any adverse effect of the biopsy procedure.