Promises and pitfalls of preimplantation genetic testing for polygenic disorders: a narrative review

Preimplantation genetic testing for polygenic disorders (PGT-P) has been commercially available since 2019. PGT-P makes use of polygenic risk scores for conditions which are multifactorial and are significantly influenced by environmental and lifestyle factors. If current predictions are accurate, then absolute risk reductions range from about 0.02% to 10.1%, meaning that between 10 and 5,000 in vitro fertilization patients would need to be tested with PGT-P to prevent one offspring from becoming affected in the future, depending on the condition and the number of embryos available. Survey and interview data reveal that patients and the public have largely favorable views regarding the use of PGT-P for disease prevention; however, clinicians and professional organizations have many reservations. The use of PGT-P raises multiple social and ethical concerns including the need for adequate counseling, the setting of realistic expectations, the application of distributive justice, the impact of environmental and social determinants of health, and the potential exacerbation of health inequities. Clinicians expressed significant concerns relating to the cost of PGT-P, the potential time-consuming counseling for reproductive endocrinologists and genetic counselors, the intentional creation of supernumerary embryos, and patients' unrealistic expectations regarding "healthiest disease-free" embryos. Furthermore, current evidence lacks long-term outcome data and generalizability. Prior to offering PGT-P to patients, additional clinical validation studies are needed. Also, ethical and social considerations raised by PGT-P should be carefully delineated. Systemic practices to increase equitable access to unbiased genetic counseling and reproductive services would be desirable prior to the ethical implementation of PGT-P.