The purpose of this research is to assess the emotional impact on mothers of children with mitochondrial disease (MD). This study plans to compare survey responses between mothers of children with MD caused by mitochondrial DNA (mtDNA) variants, which are exclusively maternally inherited, and nuclear DNA variants (nDNA), which can be inherited from either parent or new in the individual (de novo). This survey also plans to assess the impact on future reproductive decisions due to the fact that reliable preimplantation genetic testing (PGT) for mtDNA variants is lacking and the transmission of mtDNA variants from mother to child is hard to predict.