Jack Renton was found to have a missing chromosome that causes the defect before he was born, and is now awaiting surgery on a valve in his heart to rectify the problem.
The condition - known as 8p23 deletion - causes Jack's heart to SPURT blood instead of pumping it around his body. It is so rare that experts did not even recognise it as a condition until 25 years ago.
Jack's mum, Joanne Wright, 30, spoke to the Metro about the planned surgery, and said that although concerned, she was certain her son would pull through.
"'It all sounds very scary," she said, "but I've always felt in my heart he is a survivor."
Little Jack was born 19 days prematurely on May 1, this year. He has been under the care of Newcastle's Freeman Hospital, and his dad Davey Renton, 34, says he is 'putting on weight and getting stronger every day'.
The couple plan to hold Jack's christening and their wedding on the same day next year, and hope that Jack will have recovered from his surgery and be well enough to be their page boy.
"By then, we're hoping Jack's surgery will be over with," said his mum. "I thought he would be so vulnerable, but he's defied all the odds.'
"We're so proud of him," added his dad.
Aw, we hope Jack gets to be page boy too!