Non-Cancer terminal illness that can affect young (age 10-13) girls?

One of my major characters is between the ages of 10-13. She is supposed to be terminally ill and she's supposed to die at some point during the story (while still within that age range). The problem is, I'm struggling to find a terminal illness that would afflict someone this young that meet my necessary conditions:

1. It must begin having an effect on her from a very young age. (Preferably by 9, or with at least 2 years before it kills her, meaning 12 at the latest.)
2. Is terminal and can kill her by her early teens (14 years old at the latest) even with access to the best medical resources. Not that people can't live beyond that age, but that medical resources can't guarantee a prolonged life. (Clarification: It should be common enough for people to start dying from it by 14, even if it isn't guaranteed. If it can reasonably kill her by around 10, that'd be better, but I get if that's not a thing.)
3. It is NOT cancer.
4. Would leave her in the hospital frequently and for prolonged (business week-length minimum) stays.
5. Is NOT a dominant-allele genetic disorder. (If genetic, it needs to be recessive or not guaranteed to affect a person who has it. She has multiple older sisters who should be healthy is why.)
6. Does not result in any visible outward deformities.
7. I'd like for her to at least be able to walk and run on her own to some degree, but this isn't inherently a necessity. That said, she can be limited by her malady. Otherwise, the more bedridden she is, the better to help nail in the point that she is sick even if she tries not to show it.

While I could just default and use cancer, I have personal reasons why I can't do that. While I could go with a generic nameless cough, (especially since I don't plan on name-dropping the disease,) I'd rather use something specific to base my character's actions and interactions around.

The affliction can be as common or as rare as necessary. It just needs to be something that fits the desired criteria as well as possible. The best answer will fit all of the criteria. A good answer will fit most criteria. Even if I don't select your answer as the best answer, it's only because it wasn't the best for me, but it may be the best answer for somebody with slightly looser or slightly different criteria.

My question is: What diseases are terminal that can affect/kill girls of this age range and start having an effect earlier on in their lives without being guaranteed that their sisters will have it too?

World background: Real world (Japan), modern day, without magic, without sci-fi tech.

If there are other things I need to list for this to be on-topic, please let me know and I will edit to reflect that.

Before anybody criticizes the location, I have my reasons.

Modeled after similar, but different questions:

I include this because people have V2C'd this because "this question does not appear to be about worldbuilding as defined in the help center." I get that and that's why I asked that if this wasn't on-topic, to let me know what I need to include so that it is. There is a strong precedence for "Worldbuilding our real world" questions, though, with these being the questions that most closely resemble my own. There are many, many others that don't resemble my question, but are the same concept of "What in our world does this?" without stooping to disingenuous posturing. A lot of people forget that our world is so wide and varied that itself seems like fiction more often than not. Just because it exists in the real world, that doesn't mean that it doesn't need built up for people who don't know or understand. If you have a complaint with a question and feel like it should be V2C'd, please share why so the author can have an opportunity to fix whatever you feel may be broken.

In regards to the best answer:

Selecting the best answer was a challenge for this question as many answers were good or even great. If you're looking at this question because you are looking for something similar for your work, you will find quite a few good answers that may fit your needs better than the selected answer fit my listed criteria. When I got to the point where I was searching for the best answer, I was doing in depth research on a few of these conditions because that was what was needed of me. Ultimately, it boiled down to a virtual tie between Juvenile Tay–Sachs disease and Duchenne Muscular Dystrophy. Both fit my listed requirements to a tee and I needed to decide which fit my setting better in order to make the choice. Retts was a close third and Congenital Heart Defects right behind that. With 16 active answers at the time of my selecting the best answer, not all of them could be the best, but most of them were good. This was by no means an easy decision to make, but I wanted to say thank you everyone for answering, and I hope this helps others as much as it helped me!

• Comments are not for extended discussion; this conversation has been moved to chat. – L.Dutch Feb 28 at 14:50

Duchenne Muscular Dystrophy (DMD)

Unfortunately, this is a real thing. No magic, no sci-fi, no cure. It looks like it checks all the boxes, which is to say that it starts early, kills young, and overall sucks. It was the first thing that came to mind, although I could be biased by personal experiences.

1. It must begin having an effect on her from a very young age.

Muscle weakness can begin as early as age 3, first affecting the muscles of the hips, pelvic area, thighs and shoulders, and later the skeletal (voluntary) muscles in the arms, legs and trunk. The calves often are enlarged. By the early teens, the heart and respiratory muscles also are affected.

2. Is terminal and can kill her by her early teens (14 years old at the latest) even with access to the best medical resources.

Thanks to advances in cardiac and respiratory care, life expectancy is increasing and many young adults with DMD attend college, have careers, get married and have children. Survival into the early 30s is becoming more common, and there are cases of men living into their 40s and 50s.

That is, even the best, latest medicine can only hope to make it longer. The average life expectancy is 26. As seen above, by the early teenage years your cardiopulmonary system is already compromised, and it kills in the early teenage years often enough. According to a study done in 2012, approximately 10% of patients die before age 15, and 20% before age 20.

It is not.

4. Would leave her in the hospital frequently and for prolonged (business week-length minimum) stays.

Depends mainly on the state of progression. If the lungs are severely compromised, assisted breathing is common. There's a higher than average risk of cardiomyopathy, which may necessitate surgery, etc.

5. Is NOT a dominant-allele genetic disorder. (If genetic, it needs to be recessive or not guaranteed to affect a person who has it. She has multiple older sisters who should be healthy is why.)

DMD carriers are females who have a normal dystrophin gene on one X chromosome and an abnormal dystrophin gene on the other X chromosome. Most carriers of DMD do not themselves have signs and symptoms of the disease, but a minority do.

It's rare, but possible, for a female to be affected by DMD, rather than just being a carrier. You say she has healthy sisters, so this fits perfectly with that. It would mean they are likely carriers (and should probably get tested to know for sure). Indeed, it especially fits because it's unexpected in females.

6. Does not result in any visible outward deformities.

The main visible side effects are enlarged calves and curvature of the spine. They don't happen in all cases, though, and usually not until the later stages.

7. I'd like for her to at least be able to walk and run on her own to some degree, but this isn't inherently a necessity. That said, she can be limited by her malady. Otherwise, the more bedridden she is, the better to help nail in the point that she is sick even if she tries not to show it.

Sooner or later, a wheelchair is needed in DMD, typically by about age 12. Unless there's an injury, such as a broken leg, wheelchair use usually is gradual. Many at first use wheelchairs for long distances, such as at school or the mall, and continue to walk at home.

Braces, standing frames, and wheelchairs are commonly used, but until the end stages, walking is encouraged because regular exercise helps keep the symptoms from progressing as quickly.

The quoted information came from the Muscular Dystrophy Association, and associated links from that page.

• Perhaps coupled with some childhood trauma or infection this could perhaps be timed to kill at the required early age. Nasty things out there. – KalleMP Feb 27 at 20:01
• @KalleMP That's a possibility for story-writing purposes, but an additional trauma or infection isn't required. While the average life expectancy may now be 26, around 10% of patients die before age 15, and 20% by age 20. It's usually the lungs or heart giving out :( – Geobits Feb 27 at 20:09
• Hi, I appreciate your input, and this shockingly fits what I want really well. I need to review the other answers before determining which fits my question the best, but this is an AMAZING answer! That said, I do appreciate your answer and hope to hear more from you in the future! :) – Sora Tamashii Mar 1 at 10:18

Congenital heart disease.

https://www.marchofdimes.org/baby/congenital-heart-defects.aspx

Congenital means present at birth. Congenital heart defects are heart conditions that a baby’s born with. These conditions can affect the heart’s shape or how it works, or both.

Congenital heart defects are the most common types of birth defects. Birth defects are health conditions that a baby’s born with that change the shape or function of one or more parts of the body. They can cause problems in overall health, how the body develops, or in how the body works.

Congenital heart disease lends itself to a story because the children are cognitively normal, not contagious, not as harsh as someone with cancer but limited for cardiopulmonary reasons. They can be maintained with surgery and medical care but many die young - in childhood or young adulthood. Some can be cured with a heart transplant but even if that is a possibility for your character, transplant recipients still have issues and of course can also have issues from the immunosuppression required to keep the transplant.

If you leave it at that - girl tends to be blue, out of breath, sickly, born that way - that would suffice for a story. If you need to get into the weeds read more on Tetrology of Fallot. It is one of several congenital cardiac syndromes that could work for you.

• +1 and premature birth seems to be a common indicator of congenital heart defects – Quasi_Stomach Feb 25 at 18:40
• aka the stereotypical "weak heart" you find in anime. – ratchet freak Feb 26 at 12:44
• This is certainly a possibility, though I would note that many, if not most, congenital heart defects are not terminal by preteen years (or even at all) in countries with modern medical technology. For example, I was born with such a disease and it was permanently surgically cured when I was around 7 years old. Other types aren't necessarily curable, but may still allow lifespans far beyond preteen years. – reirab Feb 28 at 8:59
• @reirab - you are correct that health impact of congenital heart issue depends very much on tech level and congratulations on your cure. I linked Tetralogy of Fallot because although with current tech many are cured some people continue to have issues into late childhood / early adulthood, chiefly with underperforming valves and these people are at risk for arrhythmia and death. The character can be one of those. – Willk Feb 28 at 15:33
• Thanks @Willk for your answer! This was initially my favorite answer because it seemed like a great fit, and it is, but it doesn't seem like the best fit for MY purposes, simply because it's so common for transplant/surgery to "cure" the issue, and even if it doesn't do that, late childhood/early adulthood is too late for my purposes for typical death, but I understand that does not exclude a death at 14 from it, but I will be going with something a little more consistent in that regard. That said, I am really grateful (+1'd even) for your answer and hope to hear more from you in the future! – Sora Tamashii Mar 5 at 10:43

Cystic fibrosis

Despite the name, the problem there is you produce much thicker body fluids than normal. The largest problem is mucus, which can coat the linings of the lungs, thus causing problems like lung infections, which often require long hospital stays to fix. It's often caught in infanthood, but there's no way to treat the underlying problem, so you treat the symptoms. Some cases do manifest outwardly (and subtly), but many do not.

As to it being an inheritable trait, it's quite possible that she got unlucky in the gene pool

Every person has two copies of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. A person must inherit two copies of the CFTR gene that contain mutations -- one copy from each parent -- to have cystic fibrosis.

Her sisters are healthy because they got one good gene (they are still carriers of the bad one, though).

This fits your story well, because she could seem to be holding up fairly well, and then abruptly take a turn for the worse and die from a lung infection.

• As someone who knew a kid who passed away with this disease around 16 or so, this a good answer. – Captain Man Feb 25 at 18:27
• It's also possible that she got one copy of the bad gene from a parent and one from a spontaneous mutation. – Mark Feb 25 at 21:36
• CF rarely kills people by 16. – forest Feb 25 at 22:43
• @DeNovo Sure, but it violates "14 years old at the latest" requirement. Additionally, medical treatment can (virtually) guarantee a prolonged life, even if it can't be cured. – forest Feb 26 at 6:41
• @forest Putting in a clarification. "14 years old at the latest" was to deter answers suggesting things that don't normally negatively-affect/kill people until much later in life, even if diagnosed as a child. Will edit Q to better reflect intent. I thought "Not that people can't live beyond that age, but that medical resources can't guarantee a prolonged life." would have sufficed, but I understand the confusion. – Sora Tamashii Feb 26 at 14:12

Juvenile Tay–Sachs disease

While the more common infantile form is typically lethal before the age of 4, the much rarer juvenile version will see your unfortunate girl dead anywhere between ages 5 and 15. This disease is caused by a mutation that prevents cells from breaking down a certain waste molecule. This molecule continues to build up inside cells over a period of years until it reaches toxic levels and begins killing neurons. Like the more common infantile form, it is invariably fatal.

It must begin having an effect on her from a very young age.

The onset typically occurs between ages 2 and 6.

Is terminal and can kill her by her early teens (14 years old at the latest) even with access to the best medical resources. Not that people can't live beyond that age, but that medical resources can't guarantee a prolonged life.

She will likely die a preteen or young teenager, depending on how severe the case is. Treatment is entirely supportive, easing the symptoms (cognitive and motor skill deterioration, dysarthria, dysphagia, ataxia, and spasticity) but incapable of prolonging life.

It is NOT cancer.

Juvenile Tay–Sachs disease is a mutation in the beta-hexosaminidase A enzyme. This enzyme typically breaks down a waste molecule called GM2 ganglioside. As people afflicted with this disorder are incapable of breaking down this ganglioside, it builds up to toxic levels in cells over a period of years.

Cancer on the other hand is caused by a mutation in genes responsible for regulating cell division and growth, causing an unregulated proliferation of mutated cells. Tay–Sachs has nothing to do with this.

Would leave her in the hospital frequently and for prolonged (business week-length minimum) stays.

As treatment is supportive, frequent hospital visits are likely.

Is NOT a dominant-allele genetic disorder. (If genetic, it needs to be recessive or not guaranteed to affect a person who has it. She has multiple sisters who should be healthy is why.)

The disease is inherited in an autosomal recessive manner. It is a mutation on the HEXA gene on chromosome 15. Note that it is possible for a dominant-allele to appear spontaneously in someone with no family history of the disease due to random mutations. It would not be impossible to have a fatal illness caused by a dominant mutation while having perfectly healthy sisters.

Does not result in any visible outward deformities.

The disease primarily affects the nervous system.

• It's worth noting that this would implies a certain ancestry for the character. Tay-sachs is a very localized genetic disorder only found in a few specific populations, most commonly Ashkenazi Jews. If the character isn't a member of one of these populations, they would almost certainly not have it. – Mason Wheeler Feb 26 at 18:55
• @MasonWheeler It's true that it would be significantly less likely, but it's already an extremely rare disease. – forest Feb 27 at 2:34
• @forest, it's still an implication worth considering, just like sickle-cell anemia implies recent African ancestry. – Mark Feb 28 at 2:44
• @Mark: Not that hard to do with a bit of inbreeding. – Sean Mar 1 at 3:42
• @forest This is an absolutely terrible disease to suffer through. I want to thank you for having shared it with me because this is something that fits quite well for what I am working with. Unfortunately, due to my setting, (as Mason Wheeler suggested when mentioning populations,) that is the only thing that really keeps this from being as viable for me as the disease I selected for my "Best Answer". (Which was not your fault, but mine for not initially stating.) Honestly, this was a tough choice, but I really do appreciate your input. Again, thank you. – Sora Tamashii Mar 5 at 11:00

You could go with a variant of the Rett Complex syndromes. It is a rare (1:10000) genetic condition which is usually acquired "de novo" (i.e. with both parents healthy), only fully understood twenty years ago, which mainly affects females (males die shortly after birth except in rare cases).

This link describes the most common and severe forms of RCS.

Some milder forms allow normal development up to a certain age (6-10 years), but have secondary cardiac involvement. As a result, the victim may experience fainting and/or seizures (which would lead to her condition being discovered), or sudden death due to cardiac arrest (triggered by physical effort, emotional stress, or idiopathic). The heart itself is healthy, so transplant is not an option.

Due to the variability of the disease, it could be plausible for a victim to show few symptoms (hand wringing, slight unsteadiness when walking, mild speech impairment, restlessness) and need nothing else except for a non-periodical SSRI course (anywhere up to two weeks' hospitalization and home follow-up).

Symptoms are progressive, and a mild form might look to a life expectancy in the forties; there would be no reason to be certain of death before age 14 (unless the form was more severe, but in that case you'd be looking at heavier development anomalies - microcephaly, etc.).

• "which mainly affects females (males die shortly after birth except in rare cases)." Not a criticism, as I know exactly what you meant (as well as the context), but this phrasing did make me laugh :) – Orangesandlemons Feb 25 at 16:32
• You beat me to it. Retts is a horrible disease. I've only seen severe cases where the girls lost cognitive abilities, couldn't talk anymore, couldn't do basic things. – Cyn Feb 26 at 0:59
• I'm sorry for taking so long in replying, but I was doing further research into Retts because I wanted to see more before I gave back an answer. This is is one of the best answers I've received on this question. The issue I have is with the requirements necessary for death prior to 14 to work, but even then, that doesn't disqualify it. While I don't think this will be the best answer for me, this answer is one of the best answers I was given. It fits most of what I am looking for and is only hindered by my age-range criteria moreso than anything. Thank you so much for your answer. :) – Sora Tamashii Mar 5 at 10:33

Depression

With the onset of puberty, she goes into a deep depression and starts to cut herself, and eventually succeeds in her own suicide.

1. Puberty can start as early as 7 years, but most commonly around 11 for girls.
2. Suicide is fatal, so if the depression causes it, then this is satisfied.
3. Non-Cancer
4. Attempted suicide will leave her hospitalized, and include time for psychiatric help.
5. Depression can have a genetic component, but not always. So this is fine.
6. As long as you don't count dark makeup and scars from self cutting, there are no physical deformities.
• Depression can absolutely lead to death, but it is not classified as an incurable terminal illness. – forest Feb 25 at 22:44
• +1 and wish I could upvote once for every tween & teen who has suffered from depression and committed suicide. Suicide, according to the NIMH, is the second leading cause of death among the OP's target age group ... and continues to be the second cause for some decades after. Depression can only be treated if caught and addressed. If your girl is found hanging in her bedroom, well, then it's too late. Classification be damned. – elemtilas Feb 26 at 11:15
• It is not depression that doesn't fit classification, it's our way of thinking about classification that doesn't fit reality. It's not "incurable" but if we understood the different types and the genetics better, we might find out there are some that are very difficult to treat (like we have with cancer, there are many types of cancer, some incurable, some with higher survival rates). The raw numbers of Depression victims are staggering though. If it were a disease of any other organ, besides the mind, it would be seen differently. – don bright Feb 27 at 0:36
• @donbright If it were a disease of any other organ besides the mind, it would likely be much easier to treat as well. Can't exactly give someone a brain transplant, for obvious reasons. – Onyz Feb 27 at 11:58
• Hi, I appreciate your input, but Depression sadly does not work for me on its own. While it technically can result in suicide, that does not make the condition itself "terminal". Additionally, with access to the best medical resources, (psychiatry being a field of medicine,) she'd likely be able to get the help she needs making this unlikely to continue after the first attempt or two. That said, I do appreciate your answer and hope to hear more from you in the future! :) – Sora Tamashii Mar 1 at 11:36

On a historical note, tuberculosis used to kill a broad range of ages, and can take years to kill. In this case, you need only specify that this is a new strain, and one which is resistant to all current antibiotics. Which is not at all a far-fetched assertion, since strains exist which are, in fact, resistant to the major antibiotics. Google on "drug resistant tuberculosis".

• Unfortunately, if you don't name-drop it, tuberculosis is the "generic nameless cough" that the OP wants to avoid. – Mark Feb 25 at 21:47
• @Mark - Prolonged, helpless spasms of coughing which bring up blood are not, as far as I know, referred to as "generic nameless cough". – WhatRoughBeast Feb 26 at 0:05
• Only if you describe the symptoms with great accuracy. If you don't, you get Victorian Novel Disease. – Mark Feb 26 at 4:35
• It's notable that the OP is obviously creating an example of the Ill Girl trope, which pretty much grew out of the Victorian Novel Disease version of TB. If they wanted TB, they knew where to find it. – Ben Barden Feb 26 at 14:28
• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review – Frostfyre Mar 1 at 14:01

Kidney failure

This could be from ingesting some toxic substance, or through some developmental abnormality. There are inherited conditions which would cause this as well, but there are plenty of other possibilities.

Dialysis is required for any kind of medium-term survival. However it does not work forever. Eventually toxins will build up to damaging levels, and the patient dies. Or the patient develops sepsis or some other hospital-related bug and dies.

A kidney transplant will solve the problem. However there are many more patients needing transplants than there are matched donor organs. Sadly, many patients do die whilst waiting for a suitable donor organ.

• Hi, I appreciate your input, but unfortunately, I don't think this would work. The problem is that due to the fact she has sisters, I'd struggle explaining why none of them would be suitable live kidney donors. +1 for the otherwise great idea. That said, I do appreciate your answer and hope to hear more from you in the future! :) I'm sure this could be helpful for others either way! :) – Sora Tamashii Mar 1 at 10:31
• @SoraTamashii Relatives are not necessarily suitable donors, although usually they are. Apparently though, around 20% of potential recipients refuse live donations from family and friends because they don't want to be responsible for the risks involved. There are also various religious groups (e.g. Jehovah's Witnesses) who are opposed to organ donation - I've no idea whether Japan has any similar groups though. – Graham Mar 1 at 11:07
• With 6 sisters, one is bound to be a match. I get that, but it'd be out of character for her to refuse knowing it'd mean death since it'd put her family through so much more pain. Japan is largely atheist and Shinto Buddhist (effectively spiritual atheists). I am oversimplifying the matter greatly, but that's the shorthand of the beliefs. There are other religions, (Christianity as the largest other religion at 2.3% in 2006) but they are minorities. – Sora Tamashii Mar 1 at 11:46

One way to satisfy a lot of these conditions (especially #5) is to consider a condition that develops as a result of an injury. An injury doesn't have to leave any significant external marks, but can result in irreparable and critical damage to vital organs. This might have been caused by blunt force trauma, or being exposed to the shockwave of an explosion. Injuries can happen at any point in life, and are easy to apply to only the target character.

You can tweak the details to fit whatever story elements you wish to have. As one example, extensive damage to the renal system will impact the body's ability to filter out toxins and can require treatments like dialysis to compensate. If the kidneys' functionality is intermittent or inconsistent, you can have sudden and unpredictable build-ups of toxins that themselves can cause side-effects requiring hospitalization. Dialysis may extend life for an unpredictable period of time but won't fix the problem. The patient needs a transplant but due to her injuries, she wouldn't survive transplant surgery (perhaps due to heart damage). Instead, her choice was to continue dialysis treatments and buy as much time as she can. Perhaps the rapid hormonal changes that occur during the onset of puberty exacerbate the problem and accelerate the body's decline. You can come up with your own details of course, since injuries don't necessarily have well-defined sets of symptoms or side-effects.

• Hi, I appreciate your input, and I had lately been considering using a condition caused by injury. The only problem is coming up with an explanation that makes sense without being too violent towards a little kid for a variety of reasons. +1 for the interesting idea. That said, I do appreciate your answer and hope to hear more from you in the future! :) – Sora Tamashii Mar 1 at 9:50
• @SoraTamashii Violence towards the victim isn't necessary. For a small child, simply falling down the stairs, off a horse, etc can do terrible internal injuries. – bta Mar 1 at 20:06
• I was meaning "violence" in the general sense, but those examples are good ones I just wouldn't have thought of. While I still have to decide what I am going to do, I will keep your answer in mind. :) It's definitely a good one. Thank you. :) – Sora Tamashii Mar 2 at 13:36

Some Guy's Syndrome

Some Guy's Syndrome, named after that famous guy, you know, that one, who got the disease and raised awareness some time ago. Some Guy's Syndrome is part of the great family of Plot Diseases, that covers a wide variety of illnesses, ranging from harmless to lethal.

The effects of Some Guy's Syndrome are <insert plot-dictated effects here>. It is <viral/bacterial/genetic/magic> in nature, and is <somewhat/very/extremely/not at all> serious indeed.

In other words, describe the effects you want, slap a name on it, and voilà. Unless there is a reason you want a real disease armchair doctors will tell you doesn't work the way you want.

• +1 as this pretty much covers all the weird disease answers given thus far. – elemtilas Feb 26 at 11:08
• no prion as an option? :-( – Orangesandlemons Feb 26 at 11:36
• @Orangesandlemons If it makes you feel better, the list isn't meant to be exhaustive. It doesn't even have sentient alien spores. – AmiralPatate Feb 26 at 12:09
• The word "prion" alone gives me chills... So scary that it's outside the scale of scariness. I would prefer the alien spores. – Volker Siegel Feb 28 at 2:16
• @SoraTamashii My reasoning is rare diseases, aka orphan diseases, are a real thing. There are afflictions with weird effects, that affect one person in a million, and aren't very well understood or well researched, often without a cure as a result. There may not be one that fits exactly your case, and if there is chances are virtually nobody knows about it, but I would think making one up is an acceptable break from reality. – AmiralPatate Mar 1 at 11:15

She got AIDS from her mother during her gestation. Her mother got infected after giving birth to her older sister, so the sister is not infected. Or alternatively she could have got it via a transfusion in very young age.

Current medications of AIDS can improve life expectation, symptoms start showing from early period, however there is no cure yet.

• While there's still no cure for AIDS, with proper treatment the disease is no longer considered terminal. – Alexander Feb 25 at 18:34
• Also, this would require that the mother also has AIDS, which adds another (potentially unwanted) wrinkle to the story. – Darrel Hoffman Feb 26 at 13:49
• This is the answer used in a rather well-known animé for this exact situation. However, for the reasons outlined by Alexander, it’s actually not a good fit: For all intents and purposes, AIDS isn’t a terminal disease in a First-World country. The animé in question distinctly suffers from its choice of AIDS. – Konrad Rudolph Feb 26 at 15:08
• @KonradRudolph Oh? Didn't know that idea was done. Neat. – Sora Tamashii Mar 1 at 9:52
• Hi, I appreciate your input, and AIDs as an idea would, on the surface, work quite well, but as Alexander said, proper treatment minimizes the risk of death, just look at Magic Johnson who was diagnosed by '91. With children, it's more complicated, but the general idea unfortunately would not work as a result. That said, I do appreciate (and +1'd) your answer and hope to hear more from you in the future! :) Seriously, this was a great idea and would work in many other stories, so I think this is still good to have up for others who'd ask similar questions. :) – Sora Tamashii Mar 1 at 9:56

Progeria could potentially work for you, although I realise the main downfall with this is that it has some outward/visible manifestations (stunted growth, alopecia, and a distinctive head shape). Having said that, it seems to tick your other boxes:

Progeria is ‘premature aging’ - basically, it causes you to age at about eight times the rate of a normal human. Some people with progeria can live into their twenties, but most live only to late childhood/early teens. Wikipedia says “as there is no known cure, few people with progeria exceed 13 years of age”, which fits with the age you’re looking at for your character.

It also doesn’t necessarily affect siblings - there are some very rare cases where siblings have progeria, but it generally develops during cell division in one of the parents’ gametes, or in the newly-conceived zygote, and thus won’t impact other births.

Progeria is not cancer - and even though it can make it more likely that sufferers contract certain age-related conditions, it does not have a correlation with greater risk of cancer. (Things that are more likely include: atherosclerosis, loss of eyesight, wrinkled skin, kidney failure, and cardiovascular problems).

With all the inherent complications of the disorder, people with progeria can need to spend a lot of time in hospital. Progeria isn’t necessarily immediately noticeable, but becomes more impactful as times goes on - and would certainly be likely to have an effect by the age of 9 (and more likely by 18-24 months). However, this frequent hospitalisation wouldn’t necessarily mitigate activity - children with progeria can still be active. This may need to be less rough than for children without progeria, but swimming, walking around, bowling, etc. are certainly possible for those with progeria. The other thing with progeria is that those with the disorder do not suffer from any mental development deficiencies - on the whole, they are reported to have average to above-average intelligence, and thus can definitely take part in things on a level with those their own age, even if playing rugby might not be the most sensible option.

• Hi, I appreciate your input, but unfortunately, this suggestion Would not work for me due to the noticeable physical effects the condition has on the victim. That said, I do appreciate your answer and hope to hear more from you in the future! :) In all honesty, progeria never would have crossed my mind, and learning about it was quite an interesting experience. +1 simply for the novelty of the idea. – Sora Tamashii Mar 1 at 9:42
• I got the feeling the physical manifestations of it wouldn’t work for you, but I’m glad it was an interesting idea at least! – K. Price Mar 1 at 10:11
• It may not work for me, but I am sure it would for someone else. Thanks once again! :) – Sora Tamashii Mar 1 at 10:26

Another possibility is Batten Disease, a fatal disorder affecting the nervous system. It is caused by mutations in genes called CLN (ceroid lipofuscinosis, neuronal), which prevent the normal function of lysosomes. I believe the CLN3 form fits your needs best.

1. Manifestation at young age

The CLN3 form has a juvenile onset between ages 4-7.

2. Fatal in teenage years despite modern medicine

There are no known cures. Most children die between 15 and 30. Females according to this study even earlier.

3. Not cancer

It is not cancer.

4. Frequent hospitals visits

Symptoms like seizures, muscle stiffness and "parkinsonism" (loss of balance) can be reduced with certain drugs, which have to be adjusted in dose as severity raises. Physical therapy is also common.

5. Heredity

autosomal recessive

6. Visible outward deformities

Nope. Vision loss, cognitive decline and the symptoms described above are most common.

7. Walking/Running

This will be more affected the more the disease progresses. Vision loss is happening first, later loss of balance and muscle stiffness will take its toll.

Answer based on the good overview found here.

Haemophilia may work. I think it hits all your points, however, I am not able to confirm if it fits 5 (although I think it does).

Death could occur at puberty with the onset of menstruation.

• Haemophilia is not considered terminal. Yes, you can die from it in your teens, but in a modern setting, you almost certainly won't. – Mark Feb 26 at 0:08
• Life-altering haemophilia in women is extremely rare (and it’s virtually never life threatening). Female symptomatic carriers of haemophilia almost always have a mild form. – Konrad Rudolph Feb 26 at 15:16
• Hi, I appreciate your input, but unfortunately, this suggestion is not an answer as it misses out on one of the important parts of the question, the disease "Is terminal... even with access to the best medical resources." As haemophilia would be found at birth, it's highly unlikely that even with severe haemophilia that she'd be liable to suffer greatly from it. While complications can occur, this suggestion is unlikely to suffice due to the condition's nature. I do appreciate the answer though, and hope to hear more from you in the future! – Sora Tamashii Mar 1 at 9:19

Polio comes to mind.

I am pretty sure about points 1, 3, 4, 5

Regarding point 2: People can survive Polio, yet I guess this depends on the available treatment.

Regarding point 6: while deformations have been observed, complications vary for individuals

1. It must begin having an effect on her from a very young age.
2. Is terminal and can kill her by her early teens (14 years old at the latest) even with access to the best medical resources. Not that people can't live beyond that age, but that medical resources can't guarantee a prolonged life.
3. It is NOT cancer.
4. Would leave her in the hospital frequently and for prolonged (business week-length minimum) stays.
5. Is NOT a dominant-allele genetic disorder. (If genetic, it needs to be recessive or not guaranteed to affect a person who has it. She has multiple sisters who should be healthy is why.)
6. Does not result in any visible outward deformities.

Although not part of the required points, the original poster wants to avoid name-dropping the disease.

A teen girl that suffers through phases of lethargy or even paralysis, is a strong indication of Polio, although I grant that in the modern western world many people might be too young to immedeately think of Polio, since this disease has been successfully eradicated.

• Polio doesn't meet 2: it's not terminal. With modern medicine, less than 2% of infected children die, and if you survive the initial infection, you're almost certainly not going to die of it later. The reason why you found a "list of survivors" is that there was a particularly bad outbreak in the 1950s, infecting mostly older children and adults (who have poor survival rates) rather than the usual infants (who have very good survival rates). – Mark Feb 25 at 21:43
• Upon further investigation, it also doesn't meet criterion #0: it's not something she can believably be infected by. Polio has been completely eradicated from the Western world, and the only places with endemic polio are some regions of Afghanistan and Pakistan. – Mark Feb 25 at 21:59
• The original question stated as setting Real world, modern day, without magic, without sci-fi tech. In today's world it is perfectly possible to contract Polio: think of all the anti-vaccine people, and wide-spread global travel. Depending on where, the story is set, having Polio could range from common to extraordinary. The original question did not specify anything regarding the illness to be common or wide-spread. – Dohn Joe Feb 26 at 8:16
• For the percentage that dies from the disease, the disease is lethal. The others survive. The original question did not require 100 % lethality. The age, at which one might die from a disease, depends, among other factors, on the age at which the disease was aquired. Thus, I do not see a Polio-scenario contrary to the stated requirements. – Dohn Joe Feb 26 at 13:32
• @user568458, people aren't saying the same thing about diphtheria -- there were 33 known cases of endemic polio in 2018 confined to small regions of two countries, as compared to tens of thousands of cases of diphtheria spread across much of the world. – Mark Feb 26 at 21:04

A real-world disease that almost meeds your requirements is Sickle-cell anaemia. https://en.wikipedia.org/wiki/Sickle_cell_disease

Average life expectancy for an affected female in the Western world is around 45, but lower if advanced medical care is not available. The disease causes a series of crises throughout life, any of which could prove fatal. It's caused by inheriting a recessive gene from both parents.

It's rare for it to cause death before adulthood. It was not eliminated by evolution because inheriting the gene as a single copy conveys resistance to Malaria, and this advantage to the many outweighs the disadvantage to relatively few.

You might tweak this disease into something fictional, or simply make your character exceptionally unlucky (if she has access to modern medicine, at least). Some research might uncover a combination of this with some other normally minor condition that together create an even worse prognosis. (The common other minor condition, is ageing).

• Hi, I appreciate your input, but unfortunately, this suggestion is not an answer as it misses out on one of the important parts of the question, namely the age of death. While sickle-cell anemia is an interesting disease, from a strictly literary perspective, unfortunately, unless I change the location of my story, her being a carrier of the disease is already unlikely and her dying of it by that age is so unlikely it may as well be impossible. That said, I do appreciate your answer and hope to hear more from you in the future! :) – Sora Tamashii Mar 1 at 8:59

Your requirements pretty much match the progression of type 1 diabetes (not to be confused with more prevalent type 2) prior to the invention of insulin (1922). Death by early teens was definitely not unusual.

Even if the story is set in modern times, availability of insulin is not guaranteed in all locales, and prices/insurance in the US is trending toward making insulin less available in the near future. Other story mechanics, including a terrorist attack on production facilities could limit the availability of the medicine and accompanying supplies.

With insulin, the disease is marginally manageable but long term survival is possible. Without insulin, it’s fatal with a brutal death combining kidney failure, blindness, amputations, nerve pain, and heart disease (among other things).

Depending on the time period of the story, you would have to work in the mechanics of why insulin is limited or unavailable, which may or may not fit your current narrative.

• The question specifies "can kill her by her early teens (14 years old at the latest) even with access to the best medical resources". People with type 1 diabetes almost never die of it in their teens if they have access to insulin. (And even in the absence of insulin therapy, a ketogenic diet can increase your life expectancy; we don't know by how much, since this was discovered only a couple of years before insulin became widely available.) – Mark Feb 28 at 21:54
• My great uncle died in 1922 at age 13 from type 1, matching the OP’s timeline. Although I never met him, family lore says the advice of the day was “avoid glucose.” Minimizing carbs has been known for over a century even though “ketogenic” may be a relatively recent term. It did not prevent fatalities prior to the discovery of insulin. Although said diet may help reduce postprandial spikes, my own experience as a type 1 has shown that it has no effect on replacing missed basal insulin and cannot maintain survivable blood glucose levels absent insulin. – Thunk Feb 28 at 22:13
• The question specifies "modern day", "real world", and "access to the best medical resources". That's very different from "typical medical resources of 1922". – Mark Feb 28 at 22:18
• The point being, of course, to dispel the myth that diet alone can treat type 1 and that typical progression matches the OPs time table. As I indicated, the OP would need additional plot points to explain the absence of insulin in modern times (in developed nations, at least). – Thunk Feb 28 at 22:42
• Hi, I appreciate your input, but unfortunately, this suggestion is not an answer as it misses out on a few important parts of the question, the disease "Is terminal... even with access to the best medical resources." This should, to some degree, imply she has access to insulin if needed. Even while the cost of insulin is becoming prohibitive in the US (the story isn't set there, but you didn't know that at the time), she wouldn't have that issue. Additionally, lethality of a disease 100 years ago is not reflective of its lethality today, making it ignore the fact I state this is "modern day." – Sora Tamashii Mar 1 at 9:37

protected by Community♦Feb 28 at 13:47

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).