I am struggling to find a disease/medical condition for my character. My character is 16-year-old female with a younger sister that doesn't have the disease. If you could please help, here is the criteria that the disease needs to fit.

  1. no physical indication that she has the disease.
  2. she will die by her mid 20's ish (this can be played with a bit)
  3. she can't need to be spending heaps of time in hospital because of it.
  4. no cancer or cystic fibrosis or anything else which is cliche
  5. no cure for this disease.
  6. she lives in Sydney with her middle-class family who has access to and can pay for medical treatments.
  7. set in the current time period so nothing too extreme or crazy, please.

thank you so much!

  • 5
    $\begingroup$ Do you wish to exclude psychological issues and addicitons that can lead to death? Depression pretty much fits your description. She could spend time in the hospital, but many don't and it has a pretty high death rate. Could you perhaps describe in general a bit better what you want to do with the character? Will she just drop dead, suffer for an extended period, should everyone know or not even herself (you've got another problem then with your points btw)? Such elements seem pretty important to a story, better find a disease that fits $\endgroup$
    – Raditz_35
    Commented May 1, 2019 at 8:58
  • 6
    $\begingroup$ Does it need to be a disease? Or could it be something like a congenital heart defect? I can think of at least two actresses who had physical problems that were known before their careers started and were expected to die in their late 20s or early 30s and did. $\endgroup$
    – Brythan
    Commented May 1, 2019 at 9:32
  • 1
    $\begingroup$ I don't think it's a duplicate as the previously linked question asked for prolonged stays in hospital, while this one requires no prolonged stays in hospital. This question also requires an older age of death. The linked question is similar and can provide ideas, but not duplicate. $\endgroup$ Commented May 1, 2019 at 11:11
  • 5
    $\begingroup$ Please clarify "no physical indication that she has the disease." Do you mean she's entirely asymptomatic and the disease can literally not be diagnosed? $\endgroup$
    – Roger
    Commented May 1, 2019 at 15:28
  • 2
    $\begingroup$ Isn't this a duplicate of worldbuilding.stackexchange.com/q/139999/45960? $\endgroup$
    – forest
    Commented May 2, 2019 at 4:19

9 Answers 9


Inoperable cerebral aneurysm.

Whilst not specifically fitting some definitions of "disease" such as "caused by an invading pathogenic organism":

Having a variety of potential causes - heredity, trauma, abnormal vascular developement, high blood pressure.

These can occur in inaccesable parts of the brain like a little time bomb which can rupture and kill at any time due to minor trauma, stress or just at random times seemingly without a trigger.

  • 2
    $\begingroup$ Game of Thrones actress Emilia Clarke had operable versions of this...twice! Inoperable versions would definitely work as you can appear healthy, not spend alot of time in hospital but still attend regular apointments to keep an eye on it, while still knowing you may die at any time. $\endgroup$ Commented May 1, 2019 at 11:08
  • 3
    $\begingroup$ A friend of mine dropped dead due to this when he was in his mid 20s in the middle of the working day at his place of employment, there were no prior indications. $\endgroup$
    – Sarriesfan
    Commented May 1, 2019 at 11:22

Fatal Familial Insomnia

FFI simply put "No sleep disease", fits your description pretty nicely.

Following are the characteristics, follow the link for details:

  1. No Physical Indication.
  2. FFI is an extremely rare disorder.
  3. Often begins during middle age, but it can occur earlier or later in life.
  4. There is no cure for FFI
  5. The lack of sleep leads to physical and mental deterioration and the disease ultimately progresses to coma or death.
  • 2
    $\begingroup$ But there is physical indication of the desease, as you pointed out in number 5: physical deterioration. If the person cannot sleep, they will be constantly physically exhausted and their healing (when sick or injured) will slow down. And that is why they will ultimately die. They don't die from FFI, but from the effect that FFI has on the body – and that effect will show. $\endgroup$
    – user64555
    Commented May 1, 2019 at 10:22
  • $\begingroup$ @user10915156 I am not sure, but I think that the patient will simply look too tired, and one cannot tell if the victim looks like this because he is sick and not just because he is overworked, but yes after a few days there will be some signs. $\endgroup$
    – V.Aggarwal
    Commented May 1, 2019 at 10:31
  • 2
    $\begingroup$ In any way the symptoms will become apparent only a few months prior to death, so most of her life the patient will be symptom free, which probably is good enough for the OP, so +1. $\endgroup$
    – user64555
    Commented May 1, 2019 at 10:40
  • $\begingroup$ it sounds very interesting, but as pointed out by the other comments there might be some physical indication that my character has this disease. thank you for your comment though! $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:34

Suicidal tendencies

According to this article:

New research finds four genetic variants that may raise the risk of dying by suicide, regardless of environmental factors. The study also identifies hundreds of other genes that require further analysis and that may also raise the likelihood that a person dies by suicide.


Although the environment has an effect on the incidence of suicide, some studies have pointed out that genetic factors also play a key role. In fact, older studies have estimated the heritability of suicide at 50 percent.


According to the World Health Organization (WHO), almost 800,000 people die by suicide every year.

Among people aged 15–29, suicide is the second leading cause of death worldwide.

And if you've ever done some research on suicidal signs, you will see many people say their relatives never showed any signs of suicidal tendencies before doing the act. It may be that we as a society suck at noticing it, but still, fits your requirement for no external signs.

Think 13 Reasons Why.

  • 2
    $\begingroup$ While you're right, and you get my +1, this hits a little close to home for a lot of people. $\endgroup$
    – Ash
    Commented May 1, 2019 at 12:16
  • $\begingroup$ thank you very much, but my story was kinda that she got depressed/anxious because of her disease so that doesn't work too well. sorry about that, and thank you. $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:35
  • $\begingroup$ I agree with @rosie. A good storyline would be where the heroine is distressed about her impending death, not actually wanting to cause it. (I’m sorry, but you can’t describe suicidal tendencies as against her will.) $\endgroup$
    – Rafael
    Commented May 3, 2019 at 3:19
  • $\begingroup$ @Rafael for storyline quality the stack to use is Writing, not Worldbuilding. $\endgroup$ Commented May 3, 2019 at 15:24

Most diseases and medical conditions do have physical indications. The only ones that remain completely invisible and have absolutely no effect on the person prior to their sudden death are congenital defects, as @Brythan has pointed out in their comment and @Agrajag in their answer (+1).

The most common causes of death from one of these conditions are a

heart attack



both of which have become more prevalent amont young women (there are many sources, this is just an example).

  • $\begingroup$ thank you for that information, I wasn't aware of that and it makes sense. $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:35

I don't think an infectious disease will really help you here as for the most part diseases you either recover from or they kill you within a relatively short time period. This wikipedia page is a useful resource for this:


However there are a large number of medical cases where something goes wrong in the body (you already mentioned cancer) but just autoimmune problems gives a range of options:


For example Huntingdon's (https://en.wikipedia.org/wiki/Huntington%27s_disease) can start in the 20s and is an incurable degenerative disease. If one of your character's parents or siblings had the disease then they could have been tested and found to also carry the defective Huntingtin genes.

The simplest option though might be to have your character born with a defective heart or other vital organ. If the defect is inoperable or the operations were unsuccessful then she's at risk of dropping dead at any moment. She may not know when she will die but she knows it could happen at any moment.

A list of Congenital Disorders is here:


Survival rates of Congenital Heart Disease are shown here:


If you click on figures/tables there are some graphs showing how much prognosis has improved over the years but it is still nowhere near the control group.

  • 1
    $\begingroup$ Chorea Huntington has phyiscal indications of the disease before death. The movements of the patients are very conspicuous. $\endgroup$
    – user64555
    Commented May 1, 2019 at 10:25
  • $\begingroup$ @user10915156 Yes, but that is once symptoms start showing, you can be symptom-free for many years before but still have it hanging over you. $\endgroup$
    – Tim B
    Commented May 1, 2019 at 12:09
  • $\begingroup$ Getting a bit "Link Only" there. $\endgroup$
    – Ash
    Commented May 1, 2019 at 12:18
  • $\begingroup$ thank you for the links and research- much appreciated :) $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:36

Look up berry aneurysm... a structure in the blood vessels in the brain of very few individuals that can fail spectacularly. It's completely asymptomatic in the 'carrier' until the structure fails and it's almost inevitably fatal. If you choose to make it in some critical part of the arterial system you can increase the almost inevitable to guaranteed fatal.

  • $\begingroup$ thank you for your research, I'll look into it! $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:37

Have you heard of Wolfram syndrome? It's symptoms include type I diabetes mellitus, urinary problems, vision and hearing loss, and a variety of neurological and psychological disorders. Death usually occurs in middle adulthood, usually due to the build-up of neurological damage, but the psychological disorders include episodes of severe depression, impulsiveness and aggression, so there is a high chance of suicide well before then, especially when the blindness, deafness and ataxia (balance problems) set in.

She won't be blind until her late-teens/early-twenties, although she will probably be color-blind and have mild tunnel vision by the time she's sixteen. I'm not sure about the hearing loss, my resource doesn't say when or how it sets in. The ataxia won't set in until her twenties.

It is a genetic illness, but autosomal recessive, meaning both parents have to be carriers for there to be a chance of the child inheriting it - there is a possibility that her sister is an asymptomatic carrier.


How about a parasitic twin?

The twin could be have all of the manifestations of cancer without the cliché and although this would definitely be a physical indication, it needn't be visible or noticed.

At the point you need the character to die, the twin causes an obstruction or rupture in some major organ.

My thought is that the younger sister that doesn't have the disease is this twin and she was always just an illusion caused by the brain damage. However, I have no idea if this part is science-based or would fit in with your story!

  • $\begingroup$ ooh very interesting, haven't heard of that before! it would have worked really well but it doesn't fit too well in the story. will keep in mind for the next one ;) $\endgroup$
    – rosie
    Commented May 1, 2019 at 23:38

Lots of options. It depends on whether or not you want her (or her family) to be aware of the disease and things like progression speed and the symptoms before the onset of death.

Diseases that kill healthy (or apparently healthy) people:

  • Trauma (including things like drowning, electrocution, hypothermia)
  • Sepsis
  • Ruptured cerebral aneurysm
  • Ruptured other aneurysm (though uncommon in young people) - e.g. ortic, splenic artery
  • Major haemorrhage (trauma, ruptured ectopic pregnancy, bleeding stomach ulcer)
  • Cardiac arrhythmia or heart attack (there are a few difference causes for these, some overlap with next category)
  • Massive pulmonary embolism
  • Seizure
  • Some allergic reactions
  • Lots of others!

Diseases that you may know you have that may kill you that no definite effective treatment exists for (sudden death, or short period of symptoms):

  • Some cardiac causes (HOCM, long QT, acute myocarditis, Brugada)
  • Late-diagnosed cancers (may not have many specific symptoms until diagnosis, may be found with days, weeks or months only left)
  • Brain tumors (cancers or causing seizure)
  • Others exist

Diseases that can be stable and well managed for a long time and not be particularly noticeable but may deteriorate suddenly:

  • Asthma
  • Diabetes
  • Epilepsy
  • Complications of e.g. lupus (which may or may not have significant day-to-day symptoms)
  • Chronic kidney disease (treatment options exist but may not always be offered, e.g. someone who has kidney failure, gets dialysis, gets a transplant, transplant fails, declines further dialysis because it is horrendous)

Most of the untreatable neurological stuff tends to have progressive loss of function (e.g. Huntington's) so doesn't sound like it would suit.

Another option which might suit what I think you are looking for would be something like (surgically-corrected) hypoplastic left heart syndrome

  • can be identified prenatally or shortly after birth
  • usually (in Australia) treated with a series of operations which will help but not cure
  • most survive to adulthood (i.e. often die in childhood, teens, twenties)
  • may only require clinic follow up and medication (probably daily tablets)
  • family will know life expectancy
  • would not be expected to be able to do strenuous activity but may appear normal (other than some surgical scars) otherwise
  • likely to have deterioration before death - most likely progressive difficulty breathing - probably for weeks to months
  • may know of impending mortality but still higher risk for complications (flu season every year is a risk for people with
    significant pre-existing heart or lung disease)
  • i.e. may know will die for years but end can be quite sudden and 'not-quite-expecting-that-already'

If you can describe the circumstances that suit your plot I could probably give a plausible diagnosis / sequence of events.


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