The Heffernan family once again left Irish soil in a plane bound for the New York this week, to enable two-year-old Liam Heffernan to begin assessment for the life-threatening illness which claimed the life of his big sister Saoirse just two months ago.
Liam suffers from Late Infantile Batten Disease, and will undergo a series of tests at the Weill Cornell Medical Center in New York to assess if he is suitable for to take part in a medical treatment trial that could potentially save his life.
If he is approved he will become the first Irish child to receive such treatment.
Her late sister Saoirse, 5, had also been assessed for treatment but missed out on eligibility last October. She passed away at the family home in Keel, Castlemaine, Co. Kerry on January 18.
Tony and Mary, Liam’s parents, will be by their son’s side throughout the trials in the U.S.
"He's holding his own and as long as he keeps that up we're happy," Mr Heffernan told the “Evening Herald.”
Batten disease is a rare and fatal disease which effects the nervous system.