Greg’s review of The Gene: An Intimate History > Likes and Comments

Of the several million variants of biological molecules in the human body (enzymes, receptors, hormones—and so forth), only about 250—0.25 percent—are therapeutically modulated by our current pharmacopeia.

There's a missing zero here along with a factor of "several".

250 is 0.25% of 100,000

twenty-three angstroms—one-thousandth of one-thousandth of a millimeter.

OTOH, this has the "right number of zeros".

Excellent observation, Jim! I checked the passage in the book again and that's what he wrote. Comforting to know that there are some things Mukherjee can still make mistakes (I make many; math was never my strong suit). I was beginning to think he was infallible.

You should contact him at Columbia Med School. Will be happy to do so and cite you as source if you'd rather not.

It's an "occupational obsession" - since I make a living as an engineer. I'll message you for an email.