What are missense mutations?

A missense mutation is when one letter in a gene gets changed, making the body build a slightly different version of a protein.

Imagine you're building a toy car with instructions written on paper. Each word in the instruction is like a letter in a gene. If you change one letter, say, "blue" becomes "green", the color of your car changes. That’s exactly what happens with missense mutations: a small change in the instructions leads to a slightly different protein.

Think about spelling mistakes when writing a sentence. If you write “cat” instead of “bat,” it still makes sense, but it's not quite right. In the same way, a missense mutation might lead to a protein that works almost normally, just not perfectly.

A famous example is sickle cell disease, where one letter in the hemoglobin gene changes. Instead of making round red blood cells, it makes them stiff and sickle-shaped, like tiny crescent moons. This small change causes big effects, but the body still uses that protein most of the time.

So, a missense mutation is like changing just one letter in a recipe, the dish might taste a little different, but it’s still mostly recognizable!