It takes Romi Loffler about half an hour to write a sentence, spelling it out one letter at a time by blinking.

The 21-year-old, from Netherlee in East Renfrewshire, has Rett Syndrome, a genetic neurological disorder which leaves her unable to speak or move and comes with a range of health problems including epilepsy.

For years, people with the condition were assumed to have profound learning disabilities but Romi, who uses special eye-gaze technology to communicate, is hoping to challenge that belief.

After months of work, she completed the coursework for National 4 (Nat 4) history and achieved a qualification last year.

This year her aim was to go a step further and pass at Nat 5, which would require her sitting an exam.

But her hopes have been dashed by Scotland's exams body Qualifications Scotland (QS) which has rejected her family's requests for the adjustments Romi would need.

About 18 months before exam time, her college and parents began discussions with QS, asking if she could sit it one question at a time over a number of weeks or potentially months.

This would mean her sitting a different exam paper to other Nat 5 students but it would still be at the same level.

Her parents also asked if she could use a "bank" of pre-agreed relevant words that would mean she would not have to spell out every letter.

Qualifications Scotland (QS) said no despite two children using eye gaze technology to sit GCSE exams in England earlier this year.

One, who has cerebral palsy, took five months to complete the exam.

"If it can be done for GCSEs, I simply don't understand why it can't be done for Nat 5," says Romi's mum, Gael Gordon.

Qualifications Scotland suggested Romi sit the exam all in one go, but her mum said that would be impossible because communicating using her eyes is so exhausting.

Her mum said that QS had expressed concern that Romi would get an unfair advantage over other candidates.

"I think she is starting from a position of such incredible disadvantage that just getting her to the starting line is incredibly difficult," her mum said.

"She is not wanting to be given it and given a pat on the head.

"She wants to sit the exam in a way she can demonstrate everything she knows.

"It is about proving her capacity and proving her worth and showing what she can do because if she gets that certificate no-one can take that away from her."

Romi took time to spell out for BBC Scotland News how she feels about not being able to sit the exam.

"Angry," she wrote.

"Other students got the chance to get their National 5 and I didn't. That was unfair. I deserved the same chance as everyone else.

"They shouldn't expect us to fit around their exam system. The exam system should adapt so that disabled students have a fair chance to show what they know.

"People sometimes underestimate what I can do because I am disabled. A recognised qualification gives me evidence of what I can do."

Tracey Campbell, of Rett UK, said Romi had been dismissed in many areas of her life and she wanted to prove she was capable.

"To have these extra barriers put in place is completely unfair and unjust," she said.

"What has been fabulous about exam boards in England is that people have been allowed to sit their exams over a long period of time, one question at a time."

Glasgow Clyde College, where Romi studies, said she is "highly capable and committed".

Claire Donaghey, assistant principal arts and continuing education, said: "Despite considerable discussion with Qualifications Scotland, the mitigating arrangements we have proposed have not been deemed compatible with these requirements.

"We remain fully committed to supporting Romi and will continue to work constructively with her, her family and Qualifications Scotland to explore every available option and achieve the best possible outcome for her."

Qualifications Scotland said it was committed to making reasonable adjustments so that disabled learners have an equal opportunity to demonstrate their knowledge, skills and understanding.

A spokesperson said: "This year over 39,000 learners benefited from assessment arrangements.

"We also have a duty to maintain the integrity of qualifications, so must always ensure that any reasonable adjustments put in place for learners do not impact standards."