IT is the priceless playtime that a young Irish couple never thought they'd get to enjoy with their son.
But Tony and Mary Heffernan yesterday had their dream come true of watching their son Liam (2), who has a rare genetic disorder, play with his toy digger just like any other rambunctious toddler.
The couple watched in amazement as Liam -- who could hardly walk or talk just two months ago -- chatted and laughed as he reacquainted himself with his favourite toys.
The family savoured their first full day back at their Kerry home from the US where Liam -- who has Batten disease -- underwent revolutionary gene-therapy treatment.
The Heffernans returned to Ireland from Weill Cornel University Hospital early on Sunday morning -- and their first stop was at the grave of their daughter Saoirse, who died in January from the same disorder.
"Before the treatment, Liam had a vocabulary of about 20 words. Now he has about 60 or 70 words. And you just heard him saying 'juice'. It is unbelievable," said Tony.
"He is now walking around like any other two-year-old and we're absolutely thrilled with how he is doing so far."
The couple arrived back -- after five weeks in New York -- to a surprise welcome-home party at their Kerry home organised by their parents, relatives, neighbours, friends and supporters.
"I don't think they expected us back until a few hours later -- when we arrived, they were putting balloons up around the house, there was fresh baking being brought in and my father was lighting the fire in the toy room so Liam wouldn't be cold," Tony said. "There were also stacks and stacks of cards and messages of support."
So remarkable has been Liam's progress since his medical-treatment trial on May 3 that US doctors have fixed his next appointment for November -- instead of the one-month check-up that is usual for most other trial patients.
"They have given us a check-up and treatment schedule which runs up until 2026, a 15-year plan. So we are taking that as a very good sign," Tony added.
Tony and Mary still have to undertake a detailed daily checklist for any sign that Liam's gene-therapy treatment may be running into problems.
"We have to check his temperature, and his skin for any signs of bruising, marks or rashes. The results are then faxed over to New York.
"But Liam's doctors here -- Prof Fergus Leahy and Dr Eugene Cotter -- will be checking him regularly before we are scheduled to go back to the US," said Tony.
The signs, so far, are very encouraging for the family whose plight touched hearts across Ireland and the UK.
The Heffernans will mark World Batten Day this Saturday and also hope to attend a fundraising concert at University College Cork with Cara O'Sullivan and the Garda Siochana Band on June 10.