Revealing a murderer based on a genetic condition

Question

I'm writing a story, in which the detective will recognize a prescription for the victim is for relief of some genetic condition. He then claims that another character was the murderer because she was in fact his daughter (shocking everyone). He proves it by revealing some physical trait she had hidden.

I'm looking for some genetic condition that both mother and father could have that would express itself differently in the child.

I've done a lot of research, but search engines weren't made for this sort of question, and deadlines approach. I've discovered codominant genetic expressions, which seem to fit the bill, but the only examples I can find (in humans) are AB blood type and Sickle Cell Anemia, neither of which will work in the narrative. Perhaps I'm barking up the wrong tree.

My question is: Is there a genetic condition that a father could be receiving treatment for, that would express itself very differently in his daughter? I bring codominance into it because I want it to be 100%, and if both parents were carriers, that ought to do it.

Note: Successful answers should present physical symptoms that can be hidden and then revealed.

Thanks for any suggestions.

Answer 1

I'm writing a story, in which the detective will recognize a prescription for the victim is for relief of some genetic condition.

You wanted to be realistic: In the autopsy report (after any murder, they usually cut the corpse open and search for clues - and for causes of death), the genetic condition would have usually shown.

Usually, diseases/conditions do not have an identifiable prescription. As an example, Crohn's Disease (a genetic condition) is treated with antibiotics and prednisone, a combination that could also be applied for COPD, laryngitis, thyroiditis etc.

I'm looking for some genetic condition that both mother and father could have that would express itself differently in the child. I've done a lot of research, but search engines weren't made for this sort of question, and deadlines approach. I've discovered codominant genetic expressions, which seem to fit the bill, but the only examples I can find (in humans) are AB blood type and Sickle Cell Anemia, neither of which will work in the narrative. Perhaps I'm barking up the wrong tree.

Neither of which are expressed differently though. In the case of SCA, both carriers are either unaffected or show the same symptoms. I have yet to encounter a disease that can manifest itself entirely differently.

^{Source: Wikipedia}

Furthermore, two people having the same genetic disease does not inevitably make them closely related. It'd have to be a really rare one for the detective to conclude that (to everybody's surprise, so no other likeliness etc.). Today, DNA tests are performed routinely for suspects, and any unknown relationship between father and suspect (daughter) would have presented itself there.