Family Pedigree

          As you can see, only my mom's side is affected by Myotonic dystrophy. It was passed from my grandpa to my mother, then to Phil. Since the disease is autosomal dominant, you can not be a carrier without being affected. In other words, if you have one dominant allele, you have the disease. (Everyone in my family who is affected is Heterozygous for the gene). My mother is affected and my father is not, meaning that 50% of their offspring (Phil and me) would be affected. Luckily, the disease does not go to the extent that Phil would be unable to have children. If Phil married an affected individual that is heterozygous for the gene, 75% of their offspring would be affected; if Phil married an affected individual that is homozygous for the gene, all their offspring would be affected. However, Phil married an unaffected female (giving it a 50% chance), and we are fortunate enough to say that the disease is terminated in our family because Phil's only child is not affected. Now, the only way Myotonic dystrophy can return in my family is if Phil's child marries and affected individual. I'm happy that this disease is autosomal dominant rather than autosomal recessive, because I do not have to worry if I'm a carrier and if my children will have the disease...I simply know that I do not have the disease, and neither will my children, unless I marry an affected male. Hope this pedigree clears up how the disease is passed down!