What kind of illness was Kaori Miyazono suffering from?

Question

Does anyone know what kind of illness Kaori Miyazono was suffering from?

• Kaori Miyazono is a girl about 14 years old
• It has caused her to be hospitalized several times prior to the events of the series.
• The disease causes her to collapse during a violin performance
• It appears to cause her to have trouble walking, and is ameliorated by rehabilitation
• It causes seizures that can cause unconsciousness, and lead to her being placed in the ICU
• It is cured or temporarily halted by surgery, but the surgery is highly risky, and can result in patient death

According to the series' wiki, it is speculated that it was bone marrow failure,

due to the change in her skin pigmentation and the need for an operation.

Answer 1

In my theory, her disease is Friedreich's Ataxia. Symptons begins between the ages of 5 to 15. Muscle weakness in the arms and legs and loss of coordination are symptons.

It causes heart disorders. In Episode 20, she may be having a severe and painful tachycardia, and a following cardiac arrest. The surgery may be to implant a pacemaker, but another arrest killed her during the surgery.

Answer 2

My hypothesis is that she is suffering from advanced multiple sclerosis. The extreme exhaustion along with the loss of motor function in her legs (Episode 15-Liar) and hands (Episode 21- Snow) are her most obvious symptoms. However, the risky operation she undergoes is the only thing that make me question my theory.

Answer 3

It's a fictitious anime illness that functioned as a plot device as needed. There is no canonical mention of a specific illness and there would be no reason for the author to research one.

There is a YouTube video that falsely claims Kaori suffered from Friedreich's ataxia. The uploader is not a doctor or someone with any professional credentials that would allow him to make such a diagnosis. Additionally, the claim has been refuted by a number of doctors, med and premed students on the Discord and sub. If needed I can rescue some of those messages from the archives.