Mia, 17, was born with no eyes, cerebral palsy and other complications.
Next month the teenager from Rugby, in Warwickshire, will turn 18, a milestone she wasn't expected to reach.
To celebrate, her mother Fran Condry is running the London Marathon to raise money for Sense, the national disability charity.
It has supported Mia since she was three years old and her family credits it with helping her to grow into a confident and independent young person.
"When Mia was born we didn't know if she would survive," said Mrs Condry.
She added that Mia's grandfather Ed Condry, a retired bishop, even visited the intensive care unit in hospital to do a blessing.
"So it feels like a significant milestone that she's made it this far and that she's thriving and loving life," she said.
The 42-year-old primary school teacher is running the marathon with her friend and fellow teacher, Helen Andrews, and her father.
They are calling themselves team 'Rocket', which is Mia's middle name.
So far, they have raised £13,500, with fundraising events including a mini-marathon for their own pupils at Bilton Infant School in Rugby which raised £1,500.
This is the second time the mother-of-three has run the London Marathon and she said she is "excited knowing what a brilliant atmosphere and event it is".
She added that Mia will be at the forefront of her mind as she runs the 26.2 mile (42km) course.
"Thinking about what she's achieved will definitely keep me going."
The family say the owe so much to Sense.
It has provided Mia with monthly home play sessions with multi-sensory impairment practitioner Anne Cheesbrough who has been visiting her for 15 years.
"Having Anne around is just like having a friend to play, they talk laugh and get messy."
But she has also made the family realise that Mia can achieve almost anything.
"Last week she was surfing and abseiling down a mountain." said her mother.
The family's catchphrase is 'it's what you can do that counts', and next year they hope Mia will be able take part in the marathon too.
