Shane is a long-term resident of a special care unit, where dedicated staff help him get the best out of life despite his profound physical and mental handicaps.
Crucial to his progress has been his education. Like any other child, he has been brought each day from the unit to school where, with the help of an aide, he thrives on development exercises and interaction with teachers and students.
On his 18th birthday earlier this year, his parents applied for his school place to be continued, believing, as they were led to believe, that approval would be just a formality.
Ten days ago they got their answer. It didn't even bother to explain about the cutbacks that are turning their lives upside down. It just delivered a firm no.
"It's a terrible blow. I'm totally devastated for him," said his mother, Yvonne.
"He will just have to sit in the unit all day and do nothing. His life is depressing enough because he can't do anything for himself, but at least he had a routine and stimulation at school.
"He will lose his aide who he gets on brilliantly with and his learning will stop. I fear he will regress."
Yvonne, a small woman of slight build, has three younger children, one just five, and her husband has been ill for a while.
She speaks apologetically when she says she can't replace the specialist teachers and carers in her son's life.
"He's very heavy and I'm just not in a position to do for him what they can."
There was one thing she could do for him, though come out shouting.
Yvonne was one of about 100 parents and carers who demonstrated outside Leinster House yesterday to protest at cutbacks in services for people with intellectual disabilities.
Represetatives of groups from the west, south-west and mid-west travelled to Dublin to join in the protest which the organisers, NAMHI (National Association of the Mentally Handicapped of Ireland), lamented would have been much larger if those most affected could get away for a day to raise placards on the street.
The gathering was the latest in a series of protests organised by NAMHI in recent months in an effort to highlight the impact of spending cuts on the 160 groups and 28,000 people with intellectual disabilities they represent.
In January, they boycotted the Irish launch of European Year of People with Disabilities and in April, about 800 took to the streets in a mass protest.
Yesterday's event was staged as the Olympic flame journeys across Europe, soon to land in Ireland and signal the start of the Special Olympics World Games.
NAMHI information officer Clíona NcChualáin, said while the games were warmly welcomed, it would be wrong if they gave the impression that everything was rosy for people with disabilities.
"People are angry that this is going to paint a wonderful picture of things in Ireland while the international spotlight is on.
We want to highlight that things are not wonderful and that there are some very dire hardship cases out there."
Hard cases are nothing new. Siobhán McConnell, a mother of three grown-up sons, including 31-year-old Conor, who has residential care in Waterford, has never forgotten the struggle she fought to get services for him and came to the protest to express her fury at cutbacks.
John Ryan was also protesting His son Owen, 18, is, like Shane O'Sullivan, losing the school place his attendance at St Vincent's in Lisnagry, Limerick had secured him up to his last birthday.
His older son, David, 26, is autistic and in full-time residential care.