Perspective

Securing Maternal Identity: Halachic Concerns in the Age of Mitochondrial Replacement Therapy

John D. Loike, Rabbi Tzvi Flaum, and Alan Kadish

Abstract

Mitochondrial replacement therapy (MRT) encompasses assisted reproductive technologies designed to prevent the transmission of pathogenic mitochondrial DNA (mtDNA) mutations by combining the DNA in the nucleus (nuclear genome) of the intending parents with another woman’s enucleated egg that provides healthy donor-derived mtDNA. The use of advanced genomic engineering in MRT raises distinct ethical and halachic considerations regarding the ontological status of embryos containing genetic material from more than two individuals. This paper advances an original theoretical protocol, termed biparental mitochondrial replacement therapy (Bi-MRT), that mitigates the central halachic concerns associated with multi-parent embryos. In this protocol, future advances in stem cell technology could be employed to generate an enucleated gamete-like cell containing healthy mitochondria from the husband. The meiotic spindle–chromosome complex from the wife’s oocyte could then be transplanted into this reconstituted gamete, which could be subsequently fertilized with the husband’s sperm for IVF. If technically feasible and developmentally competent, the resulting embryo could potentially be transferred to the wife for gestation. By combining the wife’s nuclear genetic contribution, gestation, and parturition with the husband’s paternal DNA, this framework isolates the third-party mitochondrial contribution as a non-maternal factor, thereby reinforcing the wife’s singular claim to halachic maternity. Biparental MRT therefore represents a theoretical framework that could potentially reduce some halachic concerns associated with conventional MRT, but substantial scientific and safety barriers remain before any clinical application could be contemplated.

Rambam Maimonides Med J 2026;17(4):e0027