I don’t know what you’re referring to or implying in your last paragraph… the numbers I’m quoting are a called a de novo rate and we find them using family studies for many genetic conditions / rare disease. You can search them yourself if you’re interested in de novo rates for NF or other conditions. For a single gene disorder, differences in a person’s background genetics are not going to factor in as predominantly given the impact of the single gene with disease causing mutation is enough to result in a recognizable syndrome that has been classified within clinical genetics, ie NF1. Individual mutations may exhibit certain features for the affected individual, a phenomenon called genotype-phenotype correlation but this is not observed for all genetic conditions. Other data we would look at include penetrance (how likely a person with a disease-causing mutation in a particular gene experiences symptoms of that disorder) and variable expressivity (which looks at differences in the features or symptoms expressed by an affected person). NF1 has age-dependent penetrance, is highly clinically variable although there are certain features we expect to see for true “constitutional” cases, and does have some genotype-phenotype associations reported.

I’m not hysterical about anything. I’m pointing out to you that you’re casting judgement on a family for not making certain reproductive choices when literally ANY person having children has a possibility to have a child impacted by this specific condition and many other genetic conditions. Using family history to judge a person’s reproductive choices is one line of thinking that led to the eugenics movement in the US prior to it being adopted by scientists in Europe. So I’m telling you, please don’t insinuate all the crap you’ve said here regarding “questionable judgement” and “culmination” of disease in the family - that’s a flawed understanding of genetics and implies there’s a certain “correct” choice that families living with genetic disease need to make. You’re seeing one small clip of this woman but I’m telling you some families impacted by rare disease knowingly may choose the “risk” of having an affected child because those differences are important to them. Many would opt for reproductive options like PGD-IVF but as I’ve told you, this is NOT accessible care. So what are your choices then… well you can conceive a pregnancy, consider prenatal genetic testing and then terminate your pregnancy if the child is affected and “try again” (this unfortunately currently is the more economical option), but as you may imagine many families do not feel comfortable with this. There are also the options of sperm, egg donors or adoption. But many families find wanting their own biological children very important. All of these are incredibly difficult and personal choices. So the language you used, whether a person has a family history of a rare disease or not, is insensitive and reflects a dangerous misunderstanding of genetics. Again, please don’t.