THE ILL REPRESENTED: People pass a subway advertisement on Rare Disease Day in Beijing on February 26 (CFP)

Five years later, Lin Lin (a pseudonym) still vividly remembers how she felt the moment a nurse put an oxygen mask over her face in the emergency room: sheer loneliness and fear. Before she was admitted to the Peking Union Medical College Hospital (PUMCH) for respiratory failure, the 23-year-old had been experiencing frequent shortness of breath and chest pains for sometime. Doctors had diagnosed her with pneumothorax, an abnormal collection of air or gas in the pleural space that separates the lung from the chest wall, and assured her that she would be cured by a simple operation.

However, doctors finally discovered that Lin's case wasn't so straightforward. Although they succeeded in saving Lin's life, her new diagnosis was not much better than a death sentence. Lin suffers from LAM, a rare lung disease that currently has no cure. In LAM, abnormal, muscle-like cells begin to grow out of control in certain organs or tissues, especially the lungs, lymph nodes and kidneys. Over time, these LAM cells can grow throughout the lungs and destroy the normal lung tissue. As a result, air can't move freely in and out of the lungs. The resultant respiratory failure could lead to death.

Xu Kaifeng, Director of the Department of Respiratory Care at PUMCH, who treated Lin, said that LAM is often misdiagnosed and most patients are initially treated as sufferers of other more common respiratory diseases. Lin's diagnosis in 2006 made her one of only about 100 reported LAM cases in China.

From 2008 Lin started to take rapamycin, a medicine that was found to be helpful for controlling LAM in trials in the United States but with high toxicity. "I know that this medicine hasn't been proved an effective therapy and the side effects are obvious. However, without taking the medicine, I feel totally helpless in my fight with death," Lin said.

Taking the medicine costs 3,500 yuan ($552.39) every month, an enormous financial burden on Lin. Since rapamycin is not covered by China's basic medical insurance, she has to cover the entire cost of the medication out of her own pocket.

Worried about workplace discrimination against her disease, Lin refuses to tell her colleagues about her diagnosis. Whenever she stops for breath while walking from her office to the washroom, she pretends to be toying with her cellphone so as not to attract attention.

Lin, who founded China's first LAM patients' association, hoped that the celebration of the fifth Rare Disease Day on February 29 would raise awareness of rare diseases in China and boost relevant medical studies.

Held on the last day of February, Rare Disease Day was coordinated by the European Organization for Rare Diseases for the first time in 2008. In 2009, it went global as organizations in the United States, China and Australia also lead efforts in their respective countries to coordinate activities and promote the day. For 2012, the theme is Solidarity and the slogan is Rare but Strong Together.

An unfortunate minority

A rare disease, also referred to as an orphan disease, is any disease that affects a small percentage of the population.

Most rare diseases are genetic, and thus are present throughout the affected person's entire life, even if symptoms do not immediately appear.

No single cutoff number has been internationally agreed upon for which diseases are considered rare. In the United States, the Rare Disease Act of 2002 defines rare diseases strictly according to prevalence, specifically "any disease or condition that affects less than 200,000 persons in the United States," or about one in 1,500 people.

Though China is estimated to have more than 10 million rare disease patients, there has been no official or widely accepted definition of such diseases in the country. The lack of an official definition and comprehensive national surveys of rare diseases sheds light on how poorly these diseases are represented in medical academia and government health plans.