Meaning of macromutation

mac•ro•mu•ta•tion

Pronunciation: (mak"rō-my-tā'shun), [key]
— n. Genetics.
  1. a mutation that has a profound effect on the resulting organism, as a change in a regulatory gene that controls the expression of many structural genes.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.