Risk calculations involving consanguinity (for ABGC & ABMGG exams)

In today's video, we calculate the risk for a couple (who are 1st cousins) of having a child with Joubert syndrome, an autosomal recessive disorder. This approach can be generally used for calculating the risk for recessive disorders in any pedigree where consanguinity is present. We also contrast this approach with the approach to risk calculations when there is no consanguinity present. The 2 question prompts discussed in this video are as follows: Consanguinity A couple who are first cousins presents for preconception counseling. The brother of their shared, asymptomatic grandfather was affected by Joubert syndrome, an autosomal recessive disorder with complete penetrance. What is their risk of having a child with Joubert? No consanguinity A husband and wife present for preconception counseling. The husband’s paternal grandfather has a brother with phenylketonuria (PKU). The wife’s maternal grandmother has a brother with PKU. Assuming complete penetrance, what is the couple’s risk of having a child with PKU? Timestamps: 0:00 Introduction 1:04 Q1: Risk of a recessive disorder (with consanguinity) 5:58 Q2: Risk of a recessive disorder (no consanguinity) 10:04 Four-Step Approach for Risk Calculation without Consanguinity If you found this video helpful, please like, subscribe, and share! Consider supporting my rare disease education efforts by subscribing to the StudyRare newsletter, where I share board-style questions for ABMGG and ABGC exams each month: https://studyrare.substack.com/ Learn more about us at https://www.studyrare.com/ You can also support this channel by subscribing to this YouTube channel, following me on X/Twitter (@studyrare), or buying me a coffee: https://ko-fi.com/studyrare Thank you! Daniel