Polygenic embryo testing: understated ethics, unclear utility

In fertility medicine, preimplantation genetic testing (PGT) has been developed for two purposes: first, to improve in vitro fertilization (IVF) birth rates by assessing embryo viability; and second, to enable prospective parents to transfer for gestation only those embryos that do not carry specific rare disease genes. In 2019, just 2.1% of babies born in the United States were conceived by IVF, and only a small number of parents, mainly those with a family history of genetic conditions such as Huntington’s disease or Tay–Sachs disease, sought IVF with PGT to avoid the birth of affected children¹. That may change if PGT becomes widely available for more common diseases such as cancer, heart disease and diabetes — as proposed by Kumar et al. in this issue of Nature Medicine².

In their study, Kumar et al. describe a method to enable PGT for common diseases². To achieve this, they incorporate polygenic risk scores (PRSs), which combine the effects of many genetic variants (with individually small effects) into a single risk estimate; their contribution is the latest...