‘After seeing your interview on national television I am horrified and disgusted that a capable man such as yourself could be so naive and ugly with your use of language in the public arena,’ she wrote.
She added that she doesn’t understand why he would ‘use such a word.’
‘As you know, I have a daughter with Down Syndrome and this disgraceful comment would be referring to her if we took it literally,’ she said.
‘Mind you, I am also completely at a loss as to how waiting around on a tennis court can reflect in any way on her behaviour or anyone with an intellectual disability.
‘For one, my daughter waits for hours backstage for make-up artists, hairstylists and designers basically twiddling her thumbs during fashion shows. Does this mean she or any person who are idle are so called 'retarded'?’
Rosanne points out that ‘people with intellectual disabilities are either born that way or become that way because of sickness or an accident.
‘They do not choose to have these extra challenges that they have to face each and every day including delightful discrimination such as yours,’ she adds.
The outraged mum finished her letter by reminding the tennis star that this is the 21st century, so ‘please remember you and her are public figures and people look up to you and support you.’
‘I hope you have learned from this act of complete naivety that the 'R' word is never acceptable in any situation or used in any manner of reference.’
Madeline made history last year when she walked the runway for FDTL Moda at New York Fashion Week.
Despite her success, Rosanne told the Daily Mail last year, ‘That's not what it's about for us, we want to change people's perspectives on intellectual disability but what's important is our daily routine and just being happy.’