In simple terms, genes are like recipes for making proteins. All the cells in our bodies “read” genetic information so they can make the critical proteins necessary to stay healthy and function properly. If there is a mistake in a gene — that is, a misspelling — a protein might not be made correctly and cells in the retina might degenerate and cause vision loss.
These misspellings are called mutations, and just like a mistake in a recipe, some mutations are more devastating than others. For example, when baking a cake, let’s say there is an error in the recipe. It incorrectly calls for a quarter cup of sugar, when the right amount is a half of a cup. The cake may not taste great, but it is still edible. But let’s say the instruction for adding flour is omitted entirely. Then the cake will be a complete failure and go uneaten.