What kinds of changes can happen in just one gene?

There are different types of changes, or alterations, that may occur in just one gene; these changes can have a wide range of effects on a person's health and development.

Some genetic changes do not impact health and development (these are called benign), while some genetic changes cause a gene to not work properly (these are called pathogenic).

Genetic changes can have a range of effects on health and development. Some genes have a very important role in our bodies, for example, in the brain, while other genes may play minor roles in our body’s function.


Sometimes it’s helpful to use analogies to understand how differences in our genes can impact our health and development. Here's an example:

  • Some ingredients, like flour, are so important that we wouldn’t be able to make a cookie without it.
    • Some genes are like the flour, and our brains simply cannot function without them working the way they're supposed to.
  • Other ingredients, like salt or vanilla extract change the cookie in a way that it’s still a cookie, it just doesn’t taste exactly like we'd expect it to.
    • Other genes alter our brain function slightly so that the brain still works, it just might work a little bit differently than we'd expect.

If a person has a genetic change that causes a gene that's important in health and development to not work properly, that person may have a genetic condition.

You might also hear single gene changes called: single gene disorders, Mendelian conditions, or monogenic disorders.


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