Father and son: Colin Farrell with his son James who was born with Angelman Syndrome

Big-hearted Irish actor Colin Farrell will headline an event in Chicago this weekend to help raise money for children with Angelman Syndrome.

Farrell's son James, who celebrated his sixth birthday in September, was born with Angelman Syndrome and will need lifelong care.

Farrell has said he is honored to be helping out the gala event which will take place at the Hyatt Regency Chicago.

Farrell and former flame Kim Bordenave discovered that James Padraig had Angelman about eight months after he was born.

"It was caught pretty early because he started having seizures at about eight or nine months," says Farrell.

"For a while they said he had cerebral palsy. Then we got early intervention. Early intervention is so important — the quicker something is diagnosed then the quicker you can counteract its negative effects. So he’s great. He’s four years old now. He’s just brilliant."

Farrell was working with the Special Olympics committee when he revealed that his son had the rare disorder.

"They were asking me questions, and I didn’t talk about my son [but] I felt like I was betraying him, like it could be misconstrued as shame, which would be terrible, because he’s such a celebration, the little fella.

"So I called Jimmy’s mother Kim [Bordenave] and I cleared it with her, then I did the story.

"He’s nothing but a gift. He’s, as far as I’m concerned, exactly the way he should be. I look around and I see people who move perfectly, who walk with grace, who speak with great diction and clarity and a great use of the English language and we’re all miserable f–kers — including me, at times!

"You know, we want to be this or we want to be that, or compete with the man next to us … and then I see this fella who doesn’t move the way what’s perceived to be ‘normal’ is, and he’s as happy as can be. He’s just brilliant. It kind of blurs the line between what’s a hindrance [and what's not]."