To treat a 3-year-old with a rare immune deficiency, doctors at Comer Children’s Hospital took an unprecedented tack: they replaced his immune system by performing the first stem cell transplant on a patient with his condition.

Noah Galloy, the youngest son of Ryan and Jennifer Galloy, has returned home after the procedure last month at the Hyde Park hospital. Although he’s not out of the woods yet, he is quickly approaching the 100-day mark, when his doctor will consider the transplant a success.

Dr. Micah Bhatti “has been amazing. We truly believe without transferring our son to Comer he wouldn’t be alive today,” Jennifer Galloy said of the University of Chicago pediatric infectious disease doctor coordinating her son’s care.

Galloy, a high school English teacher who lives with her family in southwest suburban Plainfield, began to worry in January of last year when her then 2-year-old son was getting constant ear infections that didn’t get better with antibiotics. She began to think something was seriously wrong when his neck began to swell.

“He was not even sickly looking, except he was skinny and his lymph nodes were swollen,” Galloy said. He seemed relatively happy but wasn’t interested in eating and was losing weight.

“He completely fell off the growth chart,” she said.

Doctors at Advocate Hope Children’s Hospital in Oak Lawn suspected a problem with his tonsils and adenoid and removed both. But within days, the swelling in Noah’s neck increased, and his parents transferred him.

Noah tested negative for all common diseases when he arrived at Comer, but when doctors used a special camera to look down his throat, they discovered a fungal infection that was making it extremely painful for him to eat. Still, that didn’t explain the swollen lymph nodes.

Last spring, Noah tested positive for mycobacterium avium complex, or MAC, a group of bacteria that commonly infects AIDS patients and others with compromised immune systems.

Read more at DNAinfo. Written by Sam Cholke.