Derry Girls star Zoe Brown has been diagnosed with leukaemia aged four.
The tot and her twin sister Sophie played Erin Quinn's little sister Anna in the hit Irish Channel 4 sitcom.
Zoe's mum Leah Brown says her baby girl is "still smiling" after starting treatment for the form of cancer.
"She's been in theatre so many times, she gets lumbar punctures to put chemo in her spinal fluid as well and that's done under anaesthetic," she told Belfast Live.
"You never think your child is going to be in theatre at all and the last seven weeks, she has been in loads of times."
She explained that little Zoe is worried she's lost her hair saying: "I know that's not the main concern, but it's the saddest wee bit for her.
"Zoe just had the longest, thickest hair and it was the first thing anyone talked about when they saw her."
Derry Girls creator Lisa McGee sent her best wishes to the family, writing: "I am so sorry Zoe is going through this.
"She’s the most wonderful little girl and we are lucky to have her as part of our Derry Girls family.
"I’m sending her and her family strength and love.”
Zoe will need treatment up until Christmas and will have to undergo chemotherapy for two years afterwards.
A JustGiving page has been set up by a family friend to help with medical costs.
It reads: "Zoe who is twin to Sophie, 4 years old, got a diagnosis in May that she has acute lymphoblastic leukaemia.
"It all happened so fast, she has had 3 blood transfusions then has had a bone marrow biopsy. Her treatment includes lots of different chemotherapy drugs.
"The side affects of all these drugs are brutal, she can barely walk at the minute and has lost all her hair.
"It's a long road ahead so with the help of our community we can all come together and do what we can to help the family."
The fundraiser was initially set up to raise £500 but is already on close to £5,000.
Derry Girls follows the lives of a group of teenagers living in Northern Ireland during the Troubles.
It is based on creator Lisa McGee's own experience growing up in Derry in the Nineties and is the most successful Channel 4 comedy since Father Ted.
The hit show was first broadcast in 2018 and has just finished up its third and final season, which ends with the Good Friday Agreement.
Although we've said goodbye to Derry Girls for now, Lisa hasn't ruled out the possibility of a movie in years to come.
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