DMD is carried by an X-linked recessive gene. Males have only one X chromosome, so one copy of the mutated gene will cause DMD. Fathers cannot pass X-linked traits on to their sons, so the mutation is transmitted by the mother. If the mother is a carrier, and therefore one of her two X chromosomes has a DMD mutation, there is a 50% chance that a female child will inherit that mutation as one of her two X chromosomes, and be a carrier. There is a 50% chance that a male child will inherit that mutation as his one X chromosome, and therefore have DMD. So unfortunately, even though your mom and aunt did not have any sons with dmd it is possible that they were carriers. They mixing of DNA does not matter. They should be able to test you to see if you are a carrier. Who was the mother of the half-sister? How old is the son of your biological grandmother? Did he or the son of your bio mother have genetic testing? It might be that it is not duchenne MD but Beckers or another type of MD. In my family my grandmother was the carrier and had one son with DMD. 3 of her daughters were carriers for sure. One aunt had 2 boys and three girls and one son had DMD. The other aunt had eight kids 4 of each and only one boy with dmd and none of my female cousins are carriers but the other daughters did not have kids so we don't know about them. My other aunt only had 2 kids one boy who did not have dmd and one girl who never had children out of fear of it. So then my Mom only had me and I have 2 sons with DMD. So it is very hard to tell without the genetic testing if you are a carrier and even what type if in your family. I know how scary this is for you. Try not to freak out. There is still a good chance you are not a carrier. And if you are it sounds like a mild type like what is in my family. My oldest is 16 walking great and still doing great. Let me know if there is anything else I can tell you. Eileen
No it sadly does not skip, its just the luck of the draw. I wish I had know before I had my boys but I don't know if it really would have changed anything. I love my boys so much and they are super smart and awsome and I can imagine life without them. My uncle and my cousins also were told they would have short lives but all ended up living to late 30s and mid 40s.
They were also in wheelchairs by 9-12 but there are treatments now and so much emerging science. My boys are on a steriod called Deflazacort which they both started around 6 years ago. My aunts are just amazed at how well they are doing.
It is very scary. I am so sorry you have to go through this. I hope it is a girl and/or you are not a carrier. But at least you will know for sure. Let us know how it works out. This group is so supportive.
Any other questions on testing please dont hesitate to contact our Genetic Counselor, Ann Martin! She can help with any question. firstname.lastname@example.org
I just wanted to wish you good luck, DMD is not the end of the world although it is a terrible disease, both my boys were diagnosed recently they are 2 and 3 years old. Hoping with all my heart that your son does not have it, but if he has it you have found a great support group here! :)
Better double check that. If you're a carrier and have a son - you have a 50% chance of him having MD.
"About two thirds of Duchenne boys inherit the disease because their mother is a genetic carrier. At the meiosis, the cell division leading to the egg cells, each egg cell receives only one X chromosome. The probability that it is the X chromosome with the gene mutation is 50 %. Therefore on average 50 % of her sons will have Duchenne muscular dystrophy and on average 50 % of her daughters will also be carriers."