What is a genetic disease?

https://video.wixstatic.com/video/ae6dcf_a19a12865d3c4daab403ecbe08c319c5/480p/mp4/file.mp4

🧬 Why can two healthy parents have a child with a genetic disease?

Some genetic diseases are called recessive. This means that both parents can be perfectly healthy while carrying a faulty copy of the gene.

Each parent has two copies of every gene and passes only one of them on to their child.

If both parents are carriers, there are several possibilities with each pregnancy:

• a 25% chance that the child receives both faulty copies and has the disease;

• a 50% chance that the child receives one normal copy and one faulty copy: they are then a healthy carrier, without being ill;

• a 25% chance that the child receives both normal copies and is not a carrier.

👉 So being a healthy carrier means you are not ill, but you can pass the faulty copy on to your child.

This is the mechanism that can explain why two perfectly healthy parents can have a child with a recessive genetic disease.

And no: it doesn't mean the parents "passed on a disease" they had themselves. They were simply carriers without knowing it. 🩷