Gardaí are investigating the disappearance and whereabouts of the boy, who would be seven years old if still alive and last lived in an apartment in Donabate, Dublin.
A search of open ground began in Donabate this week after concerns for the boy were raised by Tusla last Friday.
Tusla said it had engaged with the missing child's family five years ago. Fr. Augustine Fokchet, Parish curate at St. Patrick's Church, Donabate, has called on anyone with information to come forward.
This is the second case of a child living in Ireland who was missing for years before the case came to the attention of authorities.
Kyran Durnin, who would be nine this year if still alive, was reported missing in August last year and a murder investigation was launched in October.
As a result, questions have arisen about the child and family agency, in particular its actions during the Covid-19 pandemic.
Children's Minister Norma Foley said Tusla is undertaking a "wellbeing check" on all cases, in particular on cases of children that were closed during Covid-19.