Britain launched a strategy to give better support, treatment and research for patients with rare diseases on Friday.
It is the first of such strategy initiated by the government on rare diseases.
British Health Minister Lord Howe said: "Millions of people in the UK are affected by the thousands of different kinds of chronically debilitating illnesses that are defined as rare diseases."
"So when looked at as a whole, rare diseases are not rare and our focus should be on making sure that no one who suffers from one is left behind," he added.
A rare disease is a life-threatening or chronically debilitating disease that affects five people or fewer in 10,000, and requires special, combined efforts to enable patients to be treated effectively.
"For the first time, we are strengthening the links between research and the treatment and care of patients with rare diseases. This is about putting those patients first, with better diagnosis, treatment and support for them and their families," Lord Howe said.
Britain is regarded as a leader in ground-breaking research to better understand and treat rare illnesses. The genomics revolution has the potential to radically transform the diagnosis and treatment of patients with rare diseases over the next 10 years.
The new strategy would help cement Britain's reputation as the driving force in this field, said the health minister.
Figures show that there are already more than 5,000 rare diseases identified and the total is steadily rising as new genetic discoveries explain previously unexplained disease patterns.
It is estimated that one in 17 people will suffer from a rare disease in the course of their lifetime. Britain is estimated to have around 3.5 million people to be affected by a rare disease at some point in their lives.
To mark the launch of the strategy, Lord Howe visited Great Ormond Street Hospital, which hosts a large number of nationally commissioned services for rare diseases.