Reported Cases of Parthenogenesis in Humans
Yes, there are documented cases of parthenogenesis in humans, though they are rare and typically result in non-viable outcomes or specific pathological conditions rather than live births. The most notable confirmed case is a human parthenogenetic chimera reported in 1995, representing viable offspring with mixed parthenogenetic and normal cell populations 1.
Documented Human Parthenogenesis Cases
Viable Parthenogenetic Chimaera
- A single case of a viable human parthenogenetic chimera was documented in 1995, demonstrating that parthenogenetic chimaerism can result in viable human offspring through non-random distribution of parthenogenetic and normal cell types 1.
- This case parallels experimental findings in mice, where chimaeric parthenogenetic-normal mice survive despite pure parthenogenetic embryos dying at early postimplantation stages 1.
Laboratory-Observed Parthenogenesis
In vitro fertilization settings have documented spontaneous parthenogenetic activation:
- In a study of approximately 800 oocytes examined prior to IVF, twelve (1.5%) exhibited evidence of parthenogenetic activation, with four undergoing cleavage and one showing normal cleavage patterns 2.
- A 2020 case report documented a 38-year-old woman with primary infertility whose retrieved oocyte spontaneously activated before ICSI, developing into an embryo with exclusively maternal genetic origin (48,XX,+17,+17 genotype) 3.
Oocytes matured from resected ovarian tissue demonstrate parthenogenetic competence:
- Over 50% of in vitro matured oocytes from resected ovarian tissue developed pronuclei after parthenogenetic activation, and 33% developed to at least the two-cell stage at 48 hours 4.
- These parthenotes continued development to 72 hours but exhibited significant blastomere fragmentation 4.
Clinical Manifestations
Spontaneous parthenogenesis in humans typically results in:
- Ovarian teratomas: A 2023 hypothesis suggests that spontaneous parthenogenesis may be more common than previously recognized, often degrading or manifesting as ovarian teratomas 5.
- Hydatidiform moles: In vivo parthenogenesis has been compared to this pathological pregnancy condition 2.
Regulatory and Research Context
The ISSCR 2021 guidelines formally recognize parthenogenetic human embryos as a distinct category:
- Parthenogenetic human embryos are defined as "formed without the contribution of human sperm" and require Category 2 specialized scientific and ethics review for research purposes 6.
- The guidelines acknowledge that parthenogenetic embryos may spontaneously develop from gametes produced by in vitro gametogenesis (IVG), though this is expected to be rare 6.
Key Clinical Implications
Important caveats for clinical practice:
- Pure parthenogenetic human embryos are not considered capable of producing viable offspring due to developmental requirements for paternally imprinted genes, particularly for extraembryonic tissue formation 1.
- Chimaeric combinations (parthenogenetic cells mixed with normally fertilized cells) represent the only documented pathway to viability 1.
- Spontaneous oocyte activation should be reported and may benefit from preimplantation genetic diagnosis to identify genetic abnormalities before embryo transfer 3.
Human parthenogenesis remains a rare phenomenon with limited viability outside of chimaeric presentations, primarily manifesting as pathological conditions or laboratory observations rather than successful reproduction.