Some people in Ireland are living with medical conditions that few others have or know about.
One such illness is pulmonary hypertension, which affects only a couple of hundred people in the country.
Karen Doherty is one of these people, and she has been living with pulmonary hypertension for 14 years.
The disease is characterised by pressure in the arteries of the lungs, which means the heart has to work harder. As a result, the right side of heart becomes enlarged, and without treatment the heart will fail.
Karen first began noticing symptoms after the birth of her daughter, from which she says she "never really recovered". These symptoms included tiredness, dizzy spells and breathlessness after exertion.
She went to her GP later the following year, who suggested she improve her fitness levels. However, this didn't work, and in October 2005 she passed out while walking upstairs.
After going back to her GP, and being sent to A&E, Karen had an ECG which found abnormalities, and she finally received her diagnosis.
She was put on oral therapies in 2010 and later started a drug trial, which worked well for two years.
However, she is now at a point in her treatment where she says she has "exhausted all the benefits", and is now on the list for a double lung transplant. If successful, her heart would eventually decrease in size.
Karen says, "I'm very lucky to have lived this long."
"When you wake up and you're still alive, you think, maybe I should stop worrying too much."
Professor Sean Gaines is a consultant at the Mater Hospital and a specialist in respiratory medicine. He says the life expectancy for people with pulmonary hypertension has greatly improved.
"When I first got involved in the area, people would have had a life expectancy of about two years."
"The new drugs that have come in have been very effective, but they're not a cure. People really do use those as bridges to keep going."
"Earlier treatment leads to better outcomes from it."