In a short video posted on YouTube by tvN's "You Quiz On The Block", Jeongyeon TWICE mentioned her biological sister - actress Seungyeon with gratitude. The female idol said that her sister is someone who is always by her side, becoming a spiritual support for her in the most difficult periods.
Jeongyeon shared that in 2020, when she had to temporarily stop her schedule due to health problems, she relied on Seungyeon a lot. Not only encouraging her spirit, Seungyeon was also the one who recognized that her younger sister's body showed signs of abnormality and advised her to go to the hospital for examination.


Thanks to her sister's urging, Jeongyeon was diagnosed with Cushing's syndrome. According to Koreaboo, this syndrome occurs when the body has an excessive amount of cortisol. Some medications can also be the cause of this condition. Common symptoms include weight gain, skin changes, fatigue, high blood pressure, and even risk of diabetes.
After being diagnosed, Jeongyeon received appropriate treatment and gradually recovered her health. The female singer expressed many words of thanks to her older sister for being by her side and supporting her during the difficult period.
Jeongyeon's revelation moved the TWICE fan community. Previously, the female idol faced many negative comments related to her appearance during her health change. Therefore, her sharing about the disease made many viewers even more heartbroken.
Some fans expressed dissatisfaction when saying that the management company JYP Entertainment has not protected Jeongyeon strongly enough against attacking comments online. However, there are also opinions that personal medical information is a private matter, fans have no right to ask artists or companies to disclose it.
However, most of the audience sent words of encouragement to the TWICE member. They said that the female singer had to go through a difficult period when she was both fighting illness and under pressure from the media and malicious comments on social networks.