Colin Farrell went on the Late Show With David Letterman late this week promoting his upcoming movie Fright Night, and in the midst opened up about his son being diagnosed with Angelman Syndrome.

Colin has two boys, James, 7, and Henry, who is about 2 years old.

"James has a condition called Angelman Syndrome and it only affects one in 30,000 children, they say," Farrell told Letterman, adding that there isn't much funding because it doesn't benefit pharmaceutical companies.

The sexy actor asked that anyone looking to help go to the Web site CureAngelman.org to make a donation.

Angelman Syndrome, or AS, is a neuro-genetic disorder that occurs in 1 in 15,000 live births, according to Angelman Syndrome Foundation Inc. The illness is often misdiagnosed as cerebral palsy or autism.

A child who has AS will have characteristics of the illness that includes developmental delay, lack of speech, seizures, and walking and balance disorders. Individuals with Angelman Syndrome will require life-long care, the foundation states.

"James started having seizures really early," Farrell said, adding that a doctor diagnosed the boy after seeing how happy he always was. "I should say my boy is a really happy boy and I've in my life been around some children who are sick or suffering and to be honest my boy is doing really good."