BGEN 3020 Lecture Notes - Lecture 6: Haemophilia B, Ryanodine Receptor, Factor Ix
3 Oct 2018
School
Department
Course
Professor
Document Summary
Polymorphism: variant with a frequency >0. 01: maintained in the population. 75 new bp changes (not in parents) 3-7 new cnvs (about 500kb of dna) 1 new mutation from a bp change. 25 genes completely inactivated carrier for 5-6 single gene disorders. Recessive in a diploid genome, losing one copy of a gene will not usually cause problems. Biochemical pathways are famously robust they can tolerate >2-fold changes in levels of substrates, enzymes, etc. so you need to lose both copies to have an effect. Example of hemophilia b: caused by mutation in factor ix, only need 5% of factor ix activity to have normal clotting, relevant for treatment strategies (enzyme replacement or gene therapy, obviously a recessive disorder. The protein produced by the normal allele cannot compensate. But are really cases of loss-of-heterozygosity (loh) Example: brca1 results in a high frequency of breast and ovarian cancer. It is inherited as an autosomal dominant disorder.
