How to calculate the risk of inheriting a genetic disease?

In order to assess the risk of a newborn suffering a certain genetic disease, first we need to know the mode of inheritance of the disease. Once we know that, we need to assess the carrier risk of the parents. To do that, we will start with the affected individual(s) in the family, and we will calculate the risk of the intermediate family members until we reach the parents. We can use the Punnett square to calculate the probabilities of carrying the different alleles, using the mode of inheritance to rule out the options that are not compatible with the disease under study. To calculate the final risk, you need to know a bit of probability!

Click on the following links to access examples for each of the modes of inheritance:

• Autosomal recessive risk calculation
• Autosomal dominant risk calculation
• X-linked dominant risk calculation
• X-linked recessive risk calculation

Video: Risk calculation crash course for an autosomal recessive genetic disease.