Children go missing in the State every year, but over the past four decades there have only been two Irish cases that compare with that of Madeleine McCann – where a child vanished and was never found.
For the families of Mary Boyle, who disappeared in Donegal, and Philip Cairns from Dublin, the search never ends and the sense of emptiness remains.
Mary vanished in 1977 at the age of six. Philip was 13 when he went missing.
This week in the McCann case, there were more appeals for information as a reconstruction of the events in the Portuguese resort of Praia da Luz on the evening of May 3, 2007, was shown on the BBC's Crimewatch.
After following the cases of the Irish children, one is left with the sad feeling that the McCanns could still be searching desperately and issuing appeals in 20 or 30 years' time.
Kate McCann summed up the sense of emptiness that families of missing children feel.
"When it's a special occasion, when you should be your happiest and Madeleine's not there, that's when it really hits home," she said.
She described it as a "family occasion when you haven't got your complete family".
Retired garda Gerry O'Carroll still talks with emotion in his voice when he recalls the case of Philip Cairns, the Dublin boy who vanished in October 1986.
As a detective sergeant stationed at Sundrive Road, Gerry was assigned to the investigation on the day of Philip's disappearance.
He told Weekend Review: "My heart leaps every time a body is found in the Wicklow mountains, and I hope that it is Philip. In my experience, it really makes a difference to a family when a body is never found and they have nowhere to kneel and pray."
In an interview for the book When Heaven Waits, published in 2007, Philip Cairns's mother, Alice, summed up the feeling of longing.
"I left the light on in the hall downstairs and in the bedroom at night. I used to listen to see if he would come in the door. You would be hoping the phone would ring and that would be him."
Next Wednesday marks the 27th anniversary of the day when Philip went missing in the Dublin southside suburb of Ballyroan.
Philip was a pupil at Colaiste Eanna, only a few minutes' walk from his home on Ballyroan Road, and had gone home for lunch.
At 1.30pm, he left his house to make the 15-minute return walk to school – but never arrived.
Visiting Ballyroan at lunchtime on a rainy afternoon this week, it is easy to understand the sense of shock that gripped the community and the entire country in the run-up to Halloween in 1986.
For a child to vanish without trace was unheard of and incomprehensible, all the more so along suburban streets of semi-detached houses in broad daylight on the short walk back to school.
Gerry worked on the case for months. Initially, over 30 officers were involved in an intensive investigation that dominated the headlines.
"This was one of the greatest mysteries of my entire career and I sometimes doubt myself, (wondering) whether we could have done more in the case."
The detective lived in the area and his own sons went to school there. "Every time I went for a walk in the woods, I was consciously or sub-consciously looking for Philip for many years afterwards."
The gardai received hundreds of calls about the case and there were all sorts of theories – including one that Philip might be the victim of some kind of satanic ritual at the Hellfire Club, an old stone structure on top of a nearby hill.
The only physical clues were offered by the discovery of Philip's schoolbag in a laneway a few hundred metres from where he had disappeared.
Gerry said: "Strangely, on the night it was found the bag was bone dry, but it had been raining heavily. Two of his religion books were missing.
'There were a number of leads that led nowhere. A couple travelling to the airport said they had spotted a boy answering Philip's description talking to someone through a car window.
"They were suspicious and even took down the car's number on a scrap of paper. They only learned that Philip had disappeared when they came back from holiday and went looking for the bit of paper but could not find it."
For the family of Mary Boyle, the anguish is no less acute and the search has never really ended. Mary, an identical twin, disappeared in March 1977 while visiting her grandparents at their home in Cashelard, Donegal.
Only recently, the singer Margo, sister of Daniel O'Donnell, has organised searches in the bogs where the girl vanished.
Mary's mother, Ann, said this year: "I pray to God every day that I will find out what happened to Mary.
"Everything changed the day that Mary vanished. The pain has never disappeared. If someone told me then I would be still be searching for her in 36 years I would never have believed them."
The sad fact remains that the McCanns, despite their relentless search for the truth about what happened to Madeleine, may be waiting just as long.