TABLE 2.

Representative quotes related to each of the three themes: importance of the label, relief to end the diagnostic journey, and factors to increase personal utility

Theme (subtheme)	Number of families who discussed each theme	Representative quotes
Importance of the label	15/15
Knowledge of future trajectory	10/15	“It was like a huge weight off our shoulders, it was like we have a name and now we can do research on it, now we can find out more about it.” ‐ C13
		“I guess it gives you a pathway, you know. You kind of know, yeah it's just that certainty. Kind of weird comfort in knowing that he's going to follow the same lines as what's expected. Just gives you some time to prepare or not be blindsided by what might come next” ‐ C10
		“I felt like I was standing at a fork in the road and each fork in the road had a door and the CDKL5 one, was, you could see through it, it was like opaque glass but I could see what that looked like… I said ‘you know I feel like you've just given me the key to that door and now we can actually move forward from the fork in the road”‐ C4
		“If we didn't get that diagnosis, we'd probably be feeling like there's something else lurking around every corner and it still can be a little bit like that with her, but we know why. But if we didn't know, we'd be living our lives on the edge of a sword just thinking what's going to happen next, what are we going to be dealing with in two months’ time, six months’ time, is she going to even be alive in a year?” – C4
Hope for the future	7/15	“Maybe in the future they might find something that can be done for that specific gene to make things change, I don't know. But if they don't find these things then they can't work on, you know, what can be done about it. And possibly even if it's just preventing other children from having it then that's a good thing too” ‐ C2
		“Reading articles like that makes you think 'maybe!', even if they say it's genetic, there's no cure; it just gives you hope that maybe one day. Like some cancers are cured now. Like leprosy before it was not cured, and it's cured now. So yeah, we hope” ‐ C3
		“You hold onto hope and you go 'well ok if it's so rare, then who knows, you know?'. The future could be bright, it could be gloomy, but it could be bright, so yeah.” ‐ C5
Relating to others	9/15	“Just knowing 'oh yes, it is a textbook thing', it's not just a random, she's not just a one off, there's other people out there like us.” ‐ C9
		“The label is, for me, for our family, it's been really important to move forward. You can then get onto like forums and connect with other people who've got the same sort of things going on. And that's huge in itself I think… it just makes you feel better, I can't really quantify that. It just does, it's helpful.” ‐ C4
		“Yeah it definitely has, just knowing what she has now, has definitely made it a lot easier to explain to people. Because so many people just stare and think ah what's happened? And now it's easier to just say this is what she has, and this is what happened, whereas before we couldn't really say that. We'd just be like 'I don't know; we don't know why she's like this'.” ‐ C13
Relief to end the diagnostic journey	10/15
		“A huge weight lifted (tearful). Yeah, I guess it wasn't anything that I'd done. It was just‐ you know, she's a one off. It was quite a big impact to have had… I think it's just the weight has lifted off the guilt that I was carrying around. Now that I know that it wasn't anything, there was nothing that could've changed it basically.” ‐ C2
		“Lots of blaming, lots of thinking like ‘who, where'd she get it from?’ Both sides, especially my husband's side, they're more like cultural beliefs it's caused by this, it's caused by that. But luckily, we did the genetic testing, so it was proven from the test that didn't come from both sides. It's a de novo mutation, yeah…it took out that part where you resent, like where you took blame. It's kind of reassuring that there was no cause, you were reassured that this was what happened to her. Unless because you can be thinking your whole life 'what caused it? what caused it?'” – C3
		“Yeah, it did make a difference though, because I wasn't constantly in the back of my mind worrying all the time. I was always wondering, was it this? was it that? did I do this? You know, she had a big fall when she was a baby and I often wondered oh god did she have brain trauma? So, I guess that would be for me the biggest result was that I just didn't question it anymore, wasn't looking for a magic cause you know.” ‐ C12
Factors that influence personal utility	13/15
		“It's really important from your researcher perspective to think about the context that came with this diagnosis, which wasn't a whole lot of other detrimental other things, it was just a piece of information… The fact that the gene mutation is there hasn't changed the presentation of what's happening with her physically, therefore there's nothing different yet. Like if all the children started to drop dead at 12 or 13 years old, then that will look completely different for us than it will look if those children are growing normally, not normally, but their normal.”‐ C1
		“I guess from the information we got that it actually wouldn't make any difference in terms of the treatment. It would just kind of confirm the diagnosis one way or another” ‐ C10
		“It would've been really nice to have had the genetic diagnosis earlier and it would've saved me 14 years of guilt. Yeah, that would've been really good actually to have had it at the time that she was diagnosed with that and when the epilepsy started and stuff like that, to actually know that it wasn't something that I'd done that it was just a random act of fate… I mean mental health is a big thing at the moment across all sectors. I mean it's not easy having a child with a disability and you see so many people and families just ripped apart by it. If you could know that there's nothing you could've done, then it probably does help.” ‐ C2
		“Yeah, just wish we could've controlled it maybe a lot earlier and maybe we wouldn't have had to go through so much. Because you only want your best for your children and when you reproduce that's all you want, you know, you want them to be healthy and you don't want anything wrong, you know.” ‐ C7
		“We always thought we'd have more, but after [affected child] and then after finding out, it's kind of made us think well what if our next kid is like [affected child] as well, like there's no way we could handle two kids like that. So yeah, we decided not to have anymore…I think we just decided that it's just too much to have anymore with all of her needs.” – C13
		“The other thing is good to know is that it won't affect [sister]. If and when she has children because I guess that's something you always think of. I've always been grateful that A was my second child because if she'd been the first one, she probably would've been the only one. Because I would've been too scared to get pregnant again in case I ended up with two like her.” ‐ C2