The condition of a young Kerry boy who underwent pioneering brain surgery in a New York hospital last year is deteriorating.

Little four-year-old Liam Heffernan from Keel is suffering from Batten’s Disease, a fatal neurological condition.

His older sister Saoirse died from the disease in 2011 and his parents have admitted that his condition is worsening.

Tony and Mary Heffernan were told when Liam underwent the surgery in New York that it would not cure him.

The Irish Examiner reports that they have noted signs that the fatal disease is progressing.

Dad Tony told the paper: “Liam has started to show some signs of deterioration, but he has a reasonable quality of life, at the moment.

“He now needs more supervision and 24-hour care. He still goes to play group most mornings, but has to have a minder with him all the time.

“We also have to keep a constant watch for seizures, which are the most dangerous thing.”

The Heffernans told the paper of their belief that the treatment which Liam received in New York has helped to prolong his life.

Liam underwent a gene transfer procedure administered to 12 locations in his brain.

The Heffernans want to help other families of children with Batten’s disease through the Saoirse Foundation and Bee for Battens organisation.

There are fewer than 10 cases in Ireland and their campaign has been broadened to include fundraising, research, and support for families who have children with other rare diseases.

Brave Liam Heffernan pictured after his stem cell treatment in NY in 2011Handout