Coronation Street spoilers follow.
Coronation Street's producer Iain MacLeod has revealed that Steve McDonald and Leanne Battersby's respective relationships will come under strain following Oliver's upcoming diagnosis.
The ITV soap has confirmed that Oliver will be diagnosed with mitochondrial disease, a life-limiting illness for which there is currently no cure.
Corrie will air these scenes in the coming weeks, as Steve and Leanne seek answers from the doctors over Oliver's unexplained seizures.
In an interview with Digital Spy and other media this week, MacLeod spoke about the big storyline – warning that Steve and Leanne's respective partners Tracy Barlow and Nick Tilsley may feel pushed out.
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MacLeod explained: "When Steve and Leanne learn that their son has a life-limiting condition, we explore how that impacts on their relationships with their other loved ones.
"Obviously Steve and Leanne are not currently a couple, but this story will draw them closer and closer together – to the point where they are bonded more tightly than they've ever been.
"The difficulty then for Nick, Tracy and other people is that they start to feel slightly shut out from that little triangle of Steve, Leanne and Oliver.
"It makes you the worst person in the world if you express that, so the difficulties for Tracy and Nick are to try and find the best way through for the person they love – while simultaneously feeling left out in the cold slightly.
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"It's a really complicated, emotional family story at its core. In the end, it will leave everybody permanently changed by it but also stronger for it.
"Once they've been through the fire, these relationships that have been tested by this extreme adversity will be much, much stronger. They will be life-long relationships."
Oliver's health has been a cause for concern since he had an unexplained seizure a few weeks ago. Next week, Steve and Leanne start to realise how serious things are, as he has to be admitted to intensive care.
Asked about taking on this storyline, MacLeod explained: "The reasons for doing it were, firstly, we felt that it was a really interesting story to tell with a modern, blended family.
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"The story features Steve, Leanne, Tracy and Nick – drawing in Gail, Emma and Amy. This big clan have to overcome the worst possible news.
"The other reason for wanting to tell the story is that the condition that Oliver has is something that most people don't really know about much. I certainly didn't know much about it, but it is relatively common and mostly underfunded from a research point of view.
"We wanted to draw a bit of attention to families in the real world who are going through a tough time and need a bit of support. Hopefully the extra exposure will lead to more charity revenue and hopefully find better treatments for this type of illness.
"We also wanted to show a story about a mother's love for her son. That's the fundamental component of it as it unfolds. It's about Leanne's love for her son and her willingness to move mountains to try and save him and help him – and make people understand what she's going through.
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"It's a passionate and heartfelt story and the cast are right behind it. Jane Danson has been talking to our charity partners in quite a lot of detail about her performance and what Leanne would feel. She's really passionate about getting this story right – as we all are.
"Oliver has a form of mitochondrial disease which can remain latent from birth, then suddenly manifest itself when the child is 3 or 4. There are hundreds of different types of mitochondrial disease and they're not all going to follow the same progression that Oliver's will.
"In his case, he's been asymptomatic until now, but suddenly starts experiencing neurological issues. Ultimately the diagnosis means that he's going to have a severely curtailed lifespan. It's the worst possible news for Steve and Leanne – and the story then becomes about their difficult journey to accepting that their child has a life-limiting condition."
Coronation Street currently airs on Mondays, Wednesdays and Fridays at 7.30pm on ITV.
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