Fraser, the four month old son of Chancellor Gordon Brown, has been diagnosed with cystic fibrosis.
People with CF have daily physiotherapy
He is one of 7,500 people in the UK with the genetic disease.
The condition will mean he is likely to need daily sessions of physiotherapy and drug treatment.
People with cystic fibrosis have an average life expectancy of 31, but advances in treatment mean those born with the disease now are living much longer.
The condition causes the glands which produce mucus, saliva and intestinal fluids not to work properly, resulting in secretions which clog vital organs, making it difficult to breathe and digest food properly.
To help with processing food, patients often take enzyme pills.
Many will also need daily physiotherapy and massages to help loosen the mucus in the lungs.
Parents are taught to do this for babies, but older children and adults are able to perform them for themselves.
Breathing exercises can also help.
Any chest infections, which those with CF are prone too, must be treated quickly with antibiotics and patients are routinely given flu jabs.
Drugs can also be taken to open the airways and control inflammation.
But those with the condition are also encouraged to take proactive steps. Exercise is recommended to help build up the upper body which helps drain the mucus.
Swimming, running and tennis are particularly useful for this.
Ed Owen, of the Cystic Fibrosis Trust, whose four-year-old daughter has cystic fibrosis, said: "The outlook is a pretty positive one in terms of treatment which allows children to live a relatively healthy and active lifestyle.
"It is a pretty rigorous heavy duty regime of medication, physiotherapy and regular hospital trips.
"But within that kids can enjoy a relatively happy lifestyle and there is every prospect Gordon and Sarah's child will have that."
Parents of children with CF are also being offered the hope of a future cure.
Researchers are currently working on gene therapy which could eventually mend or replace the faulty gene and deal with the effects of the disease.
However, such a prospect is still thought to be a few years away at least.
So for some older CF patients, lung transplants may be necessary.
One of those was Reenie Ferguson, who is now 52, but was diagnosed with cystic fibrosis when she was 24.
She had a heart and lung transplant in the 1990s after suffering from lung problems for years.
"I was in a wheelchair before the operation, but I now live a a normal life, I travel, I work part-time. It transformed my life."