A 3-year-old boy from New York is living without a cerebellum - the part of the brain responsible for motor control, balance, coordination and emotional control.

Chase Britton's doctors are bewildered by his condition - but even more puzzling - is the fact that his mother says she has ultrasound pictures that show it was there at some point during her pregnancy, wgrz.com reported.

"That is actually a fundamental part of the dilemma," said Dr. Adre du Plessis, chief of Fetal and Transitional Medicine at Children's National Medical Center in Washington, D.C. "If there was a cerebellum, what happened to it?"

Chase is also legally blind and missing his pons, which is the part of the brain stem that controls functions like sleeping and breathing.

Doctors are not sure if Chase's case is the end result of a fetal injury or a genetic abnormality.

The Brittons, who have an older son, Alex, had another son, Trey, who died four weeks after he was born in 2006. But doctors assured them Trey's condition was not genetic, and they were safe to try again.

"We knew this is what we wanted to do," said Chase's mother, Heather Britton. "And they said flukes don't happen twice."

Chase was born at 35 weeks after a complicated pregnancy. His doctors said he was healthy - but throughout his first year, Britton said things "seemed off."

"We knew he was developing a little slower, we thought it was because of the pregnancy," she said.

Chase's parents aren't sure if he will ever be able to live without assistance. Right now, his vocabulary is limited, but he continues to accomplish more each day - like potty training and learning how to use an iPad.

"Our geneticist in Buffalo told us to start a college fund, because you never know," Britton said. "So, that's our hope for him."