Katie, 39, shared her heartbreak as news of Amy's illness emerged over the weekend, taking to social media to explain that the average life expectancy for people with the disease is around 3-5 years.
'My mum has been diagnosed with a lung disease called Idiopathic pulmonary fibrosis (IPF) there is unfortunately no known cure for this,' she wrote.
'As a shock to us all, Me and my family are proud to be supporting the British lung foundation to help support awareness and raising funds for research of IPF. With this we can help in other diagnosis and create awareness for people with IPF.'
'The condition has an average life expectancy of 3-5 years. There are two known pills which if they work can slow things down.'
'My mum is a fighter. She is working out every day, going to wrok and living life to the full please help us in supporting The British Lung foundation so we can make a difference.'
Speaking to The Sun, Katie added: 'She's got something wrong with her lungs and she's been told she hasn't got very long to live.'
'She's on tablets… at last I'm making her laugh. Whatever is happening we've got to be upbeat about it.'
The announcement comes at an already difficult time for Katie, who last week revealed that her third husband Kieran Hayler had been unfaithful.
Fans have rushed to send the mum-of-five messages of support and solidarity, with one writing: 'My thoughts are with you all Katie. You're a battler, let the battle commence'.
'All my love to you, Amy and family,' another agreed. 'Bless you for bringing awareness to the condition for your mum and many others.'
According to the NHS, idiopathic pulmonary fibrosis is a condition in which the lungs become scarred and breathing becomes difficult.
'Several treatments can help reduce the rate at which IPF gets worse, but there's currently no treatment that can stop or reverse the scarring of the lungs,' the body explains.