Suddenly, Trait-Based Embryo Selection

Aug 5, 2025

The podcast dives into the groundbreaking approach of trait-based embryo selection, examining how genetic testing has evolved from visual assessments to sophisticated polygenic predictions. It discusses the ethical dilemmas and potential societal inequalities tied to 'designer babies.' Listeners learn about the challenges of accurately predicting genetic traits and the implications these choices have for future generations. The complexities of accessibility and the economic impacts are also highlighted, making it a fascinating exploration of modern reproductive technology.

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INSIGHT

Professional Societies' Vague Criticism

Professional societies oppose polygenic embryo screening, citing uncertain predictive power and stigma concerns.
These criticisms often rely on vague objections rather than scientific or ethical rigor.

INSIGHT

Within-Family Validation Improves Accuracy

Polygenic prediction works best when validated within families to avoid confounding factors.
Most companies lose about 20-25% accuracy when correcting for family-related biases.

INSIGHT

Correlated Risks Favor Selection Benefits

Genetic risks for many diseases correlate positively, so selecting against one tends to reduce others.
Antagonistic pleiotropy is uncommon, implying net benefits from polygenic embryo selection.

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[see footnote 4 for conflicts of interest]

In 2021, Genomic Prediction announced the first polygenically selected baby.

When a couple uses IVF, they may get as many as ten embryos. If they only want one child, which one do they implant? In the early days, doctors would just eyeball them and choose whichever looked healthiest. Later, they started testing for some of the most severe and easiest-to-detect genetic disorders like Down Syndrome and cystic fibrosis1. The final step was polygenic selection - genotyping each embryo and implanting the one with the best genes overall.

Best in what sense? Genomic Prediction claimed the ability to forecast health outcomes from diabetes to schizophrenia. For example, although the average person has a 30% chance of getting type II diabetes, if you genetically test five embryos and select the one with the lowest predicted risk, they'll only have a 20% chance2. Since you're taking the healthiest of many embryos, you should expect a child conceived via this method to be significantly healthier than one born naturally. Polygenic selection straddles the line between disease prevention and human enhancement.

In 2023, Orchid Health entered the field. Unlike Genomic Prediction, which tested only the most important genetic variants, Orchid offers whole genome sequencing, which can detect the de novo3 mutations involved in autism, developmental disorders, and certain other genetic diseases.

Critics accused GP and Orchid of offering "designer babies", but this was only true in the weakest sense - customers couldn't "design" a baby for anything other than slightly lower risk of genetic disease. These companies refused to offer selection on "traits" - the industry term for the really controversial stuff like height, IQ, or eye color. Still, these were trivial extensions of their technology, and everybody knew it was just a matter of time before someone took the plunge.

Last month, a startup called Nucleus took the plunge.

https://www.astralcodexten.com/p/suddenly-trait-based-embryo-selection