As Corrie boss Iain MacLeod hints the storyline will "draw them closer together than ever before."
Coronation Street viewers have already seen three-year-old Oliver become unwell whilst in the care of his dad, Steve McDonald, who briefly left him with teen Summer.
Initially, Doctors put this down to a febrile convulsion, but when Oliver suffers another seizure he is rushed to hospital for tests, where doctors start to fear his condition could be more serious.
As they await a diagnosis, Leanne and Steve try to stay strong for Oliver but a further seizure and a diagnosis of a Mitochondrial disorder, a life-threatening illness leaves them devastated.
In the months to come Leanne and Steve will be forced to come to terms with the heartbreaking diagnosis which will leave Oliver with a life limiting illness for which there is currently no cure.
Speaking to a number of press including I Talk Telly during a virtual press conference, Corrie producer Iain MacLeod talked about the decision to tackle this storyline and told us "We felt like it was a really interesting story to tell with a really modern blended family of Steve, Tracy, Leanne, Nick - also drawing in Gail and Liz and Emma and Amy - and just see a multi-faceted story where this big clang have to overcome the worst possible news."
"The other reason for wanting to tell it, is the condition that Oliver has is something that I would venture most people don't know about much. I certainly didn't know about it in any great detail before we embarked on the story. It is relatively common and it is relatively underfunded from a research point of view, so it was an opportunity to draw a bit of attention to families in the real world who are going through something really tough and need a bit of support.
"(I) hope that extra exposure will mean more charity revenue for certain charities that will help to potentially find better treatments for this illness."
Teasing where the storyline will go next, Iain described it as "A mother's love. That's the fundamental component of it as it unfolds. It becomes 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."
"It's a really passionate and heartfelt story I think. I know 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 how her character should feel. She's very passionate about getting this story right, as are we all."
Echoing what Iain said, Jane Danson who plays Leanne has spoken about the upcoming storyline and said “We’ve worked closely with Liz Curtis at The Lily Foundation. It was harrowing hearing the story of what happened to her daughter Lily but also really amazing to hear how people come through this, how they support each other and learn to live again.
"It’s almost too much to comprehend but I came away from the meeting bowled over by her bravery and how amazing she is as a human being. She shared with me how she felt emotionally, how she got through her days, how people rallied around her. I’ve also read a lot of literature about how families cope around their children’s diagnosis with life limiting illnesses, looking at the human elements to their stories amidst all the medical speak and hoping I can get it right."
Adding "It is quite overwhelming, I’ve been so lucky to have so many stories with Leanne over the last 20 odd years but this one feels different, this one could really break her and it feels like it’s the one where I’ve got the most responsibility to get it right.”
Teasing the storyline further, Iain MacLeod went on to say "In his (Oliver's) case, he's been asymptomatic until now and suddenly starts experiencing these neurological issues and ultimately the diagnosis will mean that he's going to have a seriously curtailed lifespan. Which is the worst possible news for Steve and Leanne."
"The story really then becomes about their difficult journey to accepting that ultimately their son has a life limiting condition, and also the impact that has on their relationships with their other loved ones. Steve and Leanne are not currently a couple but this story will draw them closer together, to the point where they are bonded more tightly than they're ever been."
"The difficulty then for Nick and Tracy and other people is that they start to feel slightly shut out from that little circle of Steve, Leanne and Oliver, but it makes you the worst person in the world if you express that. So the difficulties for Tracy and Nick are trying to find the best way through to support the person they love while simultaneously feeling like their being left out in the cold slightly."
On what this means for the future of these characters, Iain revealed "It's a really complicated emotional family story at its core. In the end I think it will leave everyone permanently changed by it, but also stronger for it. Once they've been through the fire, I think these relationships that have been tested in this extreme adversity will be much much stronger, life-changing and lifelong relationships."
Coronation Street’s research team worked closely with The Lily Foundation, a charity that supports families and funds research into mitochondrial disease, to ensure the storyline closely reflects the experiences of families with children with mitochondrial disorders.
Professor Robert McFarland from the Wellcome Centre for Mitochondrial Research in Newcastle was also consulted to ensure script accuracy.
Coronation Street continues Mondays, Wednesdays and Fridays at 7.30pm on ITV
*Mitochondrial disease, or 'mito', is the term given to a group of medical disorders caused by mutations in mitochondria, the tiny organelles that are present in nearly every cell in our bodies and which generate about 90% of the energy we need to live. Cells cannot function properly without healthy mitochondria, so when they fail the consequences can be serious and wide-ranging.
Mitochondrial diseases affect people in multiple ways, depending on which cells are affected. This can make the condition hard to diagnose, as symptoms often resemble those of other serious illnesses. For example, a person with mitochondrial disease may suffer from seizures, fatigue, vision and hearing loss, cognitive disabilities, respiratory problems or poor growth. Any of the body's organs and systems can be affected including the brain, heart, lungs, gut, liver and skin.
If you are affected or are living with someone who has a mitochondrial disease, for information about the disease and the support available please visit this website.