Objective: To determine the effect of mutant mitochondria on preimplantation embryo development and of preimplantation embryo development on the survival of mutant mitochondrial DNA.
Design: Laboratory research.
Setting: Academic research laboratory.
Patient(s): None.
Intervention(s): Mutant and wild-type mitochondria, fractionated from tissue obtained from a patient with MELAS syndrome, a mitochondrial disease, were microinjected into mouse zygotes. Control zygotes received either no injection or sham injection.
Main outcome measure(s): Preimplantation embryo development and survival of mutant mitochondrial DNA as determined by polymerase chain reaction analysis.
Result(s): After microinjection into zygotes, the MELAS mutation could be identified by polymerase chain reaction until the hatched blastocyst stage of embryo development. The survival of MELAS-injected zygotes, observed for 4 days after injection, did not differ from the survival of zygotes injected with wild-type mitochondria or from the survival of uninjected or sham-injected controls.
Conclusion(s): It appears that preimplantation embryo development does not screen out mitochondrial DNA mutations introduced into fertilized oocytes, and low levels of mutant mitochondrial DNA do not disrupt early embryo development.