Familial adenomatous polyposis is an autosomal dominant mutation. Thousands of polyps arise starting after puberty; pancolonic; always involves rectum. Prophylactic colectomy or else 100% progress to CRC.
Autosomal dominant diseases have, on average, 50% chance of being passed down to offspring.
sympathetikeyI would say this is Lynch Syndrome (APC is usually thousands of polyps) but lynch syndrome would generally have a family history of other cancers as well, so you might be right. Either way, both autosomal dominant so win win.+3
smc213uptodate states: Classic FAP is characterized by the presence of 100 or more adenomatous colorectal polyps+
dickass@sympathetikey Lynch Syndrome is literally called "Hereditary NON-POLYPOSIS colorectal cancer"+14
fatboyslimI think this actually is Lynch syndrome. Lynch syndrome can also develop colonic polyps but not nearly as bad as FAP. FAP has so many polyps you can't even see the normal mucosa. If you Google Lynch colonoscopy you can see that they develop a few polyps.+
rockodudeI forgot it was AD inheritance but regardless at the time I was confused because APC is a tumor suppressor so it needs two hits. I guess AD inheritance and then you need another hit to develop CRC kind of like familial retinoblastoma or li fraumeni syndrome +
I don't know why I feel the correct answer is 100%. The ques states, "what is the chance that offsprings will EVENTUALLY develop cancer?, not inherit the mutation"
Prophylactic colectomy or else 100% EVENTUALLY progress to CRC.
lilyoI also chose 100% with that same reasoning!!!+
lilyo@usmlecrasher, Yes it does so which is why if they inherited they have 100% chance of developing colon cancer later in life and the question was confusing because it didnt ask what is the percentage that this patient will have children with this mutation? It might be my language barrier but I don't know.+
diegolc26Its a little tricky bk they want you to think the probability of developing cancer IF the offspring HAS the mutation, which is 50%. I mean, he has 50% chances of inheriting the cancer developing mutation. Thats how I think they want to trick us. +2
mbourne@cryus_em, you're putting way too much emphasis on the word "eventually". Either way the question and answer makes sense. It's an AD disease, so the chance of the offspring inheriting it would be 50% (and if they inherit it, they WILL develop adenocarcinoma of the colon, so the answer is still 50%).+1
heenaasnaniIf they inherit the mutation (chances of inheriting the mutation is 50%), they will develop the carcinoma for sure. I hope this helped.+
allora__I understand that if she is heterozygous Aa the odds she passes the allele down is 50%, but can you please explain how we can assume she is heterozygous to begin with? If she were homozygous AA, then there would be 100% chance that her children inherit the disease. Feel like I may be missing a simple concept here.. +1
plaguedbyspleen@allora_ I had to think long a hard about this too but then it came to me. For her to be autosomal dominant, both her mother and father would have to be heterozygous. Then both would have to give her the allele. The stem just mentions her father and grandfather so you can assume the mother did not have the disease. +
plaguedbyspleenCorrection: for her to be AA her parents would both have to be AT LEAST heterozygous Aa. +
submitted by โhayayah(1212)
Familial adenomatous polyposis is an autosomal dominant mutation. Thousands of polyps arise starting after puberty; pancolonic; always involves rectum. Prophylactic colectomy or else 100% progress to CRC.
Autosomal dominant diseases have, on average, 50% chance of being passed down to offspring.