When Nicholas Cromer was happy, he let the people around him know.

“He had a way that he’d tilt his head back and close his eyes and just laugh the most contagious laugh,” said Mary Subra, an occupational therapist who worked with Nicholas for more than 10 years. “And you just couldn’t help but laugh with him.

Nicholas Elliott Cromer, of McDonough, was born with a mitochondrial disorder which affected his growth and cognitive development, his mother Sonya Cromer said. He was diagnosed with leukemia in August 2010, and he died Friday from complications associated with the disease. He was 12. A memorial service will be held at 2 p.m. Wednesday at St. Philip AME Church, 240 Candler Road, Atlanta. Nicholas’ parents said they decided to have his body cremated so that if they relocate, their son can remain with the family. Cannon Cleveland Funeral Directors is in charge of arrangements.

Mrs. Cromer said her son was the center of the family. Though he did not communicate verbally, Nicholas was adept at letting people know what he wanted, she said.

“If he wanted to eat he’d go sit at the kitchen table,” Mrs. Cromer said. “Or he’d take me by the hand and put my hand on the microwave. We got a kick out of that because it was like he was saying ‘Mommy doesn’t cook, she microwaves,’ but I do cook on the stove a lot. That’s what made it so funny to us.”

Mrs. Cromer even taught herself how to cook two of Nicholas’ favorite dishes, carrot soufflé and sweet potato soufflé.

“He wouldn’t eat if he didn’t see that orange on his plate,” his mother said. “It was so funny, he’d scan his plate until he saw it, and then he’d start eating.”

Nicholas loved to do a lot of things, but at the top of that list was running, friends and family said.

“He’d just take off running, when he was able,” Mrs. Cromer said. “And he liked it even more if you’d chase him.”

Mrs. Subra said Nicholas would wait for the opportune moment before he would dash off, in an unexpected direction.

“He’d never give you any indication he was watching you, but he knew the instant you weren’t watching him,” she said. “Because the second you looked away, he’d take off and run and then he’d just laugh. He was such a joy.”

Nicholas also loved music, said his grandmother Hattie Bell, of Jonesboro. He would dart into the room where there was a piano and “try to pick out a tune,” she said.

“See, I used to tell the others to go in there and practice,” Mrs. Bell said. “And sometimes we’d hear music coming from in there, and we’d look around to see who it could be. And it would be Nicholas, and he’d be in there just playing away.”

Nicholas was responsible for bringing laughter into the lives of many, family and friends say. And stories of him will continue to keep people laughing for years to come, his mother said.

“Anyone who knew Nicholas, or had us in their home can tell you a story about something he did that tickled them,” she said. “He always amazed us, and we loved it.”

Nicholas is also survived by his father, Keith Cromer; brother, Brandon Cromer and sister, Mckenzie Cromer, all of McDonough.