Lady Gaga made one little boy's day in Chicago today. The lucky boy was Coltrane, a 2-year-old cool kid from Oakland, California who has Joubert syndrome, a very rare birth defect that affects about 1 in 100,000 children.

Coltrane and his parents are in Chicago for the 2015 Joubert Syndrome Conference, and as they were enjoying the sunny day in the city, they bumped into none other than Mother Monster herself.

"Lady Gaga talked to Coltrane for a few minutes and we got to tell her about Joubert syndrome and the conference this week," Coltrane's father Oscar told Gaga Daily. "I tried to talk calmly while screaming inside. She told us about her Born This Way Foundation. Sweet, charming and genuinely interested, initially approached us about his wheelchair. I was spooning him some Greek yogurt and chatting it up with people sitting by us. I love Lady Gaga and to know she is aware of Joubert syndrome makes me so happy."

The boy's mother, Ayah, added: "We had a good conversation about the genius of John Coltrane, Joubert Syndrome and how people are 'born this way'! Sweetest lady, that Mother Monster."

Joubert syndrome is a rare genetic disorder characterized by the absence or underdevelopment of the area of the brain that controls muscle coordination. Liver and kidney malformations are often associated with the disease. To find out more about Joubert syndrome, please visit the Joubert Syndrome Foundation.

Many thanks to Oscar Vivanco for sharing the story and pictures with us.