Hemophilia pedigree
Pedigree is a method that describes the inheritance of the inherited disease, and the previous pedigree describes the pattern of hemophilia in Queen Victoria’s children. Question marks indicate the kids whose case is unknown. The descendants in the third and fourth generations didn’t receive the mutant gene; thus, we deleted them.
New work explains that the mutation was in the gene for factor 9 (IX), so the condition was hemophilia B. The examination of the DNA samples of the Russian Royal family showed:
- A point mutation in factor IX (F9) gene
- The mutation site caused a frameshift that resulted in a shortened, nonfunctional protein.
- As the pedigree shows, the DNA of Alexandra contained a mutant allele; thus, she was a carrier.
- Was this one of her four Daughters (referred to as “4?” in the fourth row and Presumably Anastasia)?
- However, the DNA of Czarevitch Alexis contained only the mutant allele, which accounts for his previous history of severe bleeding.
