Christina Applegate has revealed she has been diagnosed with multiple sclerosis (MS).

The Emmy-winning actress is widely known for her cameo in Friends as Rachel’s sister Amy, but has also appeared in a raft of films and TV shows.

Tweeting on Tuesday, the star wrote: “Hi friends. A few months ago I was diagnosed with MS. It’s been a strange journey.

“But I have been so supported by people that I know who also have this condition. It’s been a tough road. But as we all know, the road keeps going. Unless some a****** blocks it.”

She later added: “As one of my friends that has MS said ‘we wake up and take the indicated action’.

“And that’s what I do. So now I ask for privacy. As I go through this thing. Thank you xo”.

MS is a lifelong condition that affects the brain and nerves, according to the NHS.

Its symptoms include fatigue, vision problems and issues with balance and coordination.

Those with the condition tend not to recover and there is no known cure, but there are treatments to help with symptoms available which include steroids and therapies.

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Though it is not fatal in itself, it does lower life expectancy by up to 10 years.

Her diagnosis comes several years after she revealed she had breast cancer – from which she made a full recovery following a double mastectomy.

Applegate was made a household name when she was a teenager when she took on the role of Kelly Bundy in Married… With Children.

She is also known for playing Veronica Corningstone in Anchorman and its sequel, as well as taking on the lead role of Jen Harding in the Netflix show Dead To Me.