Twins Zoey and Zane Espayos had the odds stacked against them before even leaving the womb.
The Manitoba, Canada, natives were diagnosed with alpha thalassemia when their mother Reina was 27 weeks pregnant. Zoey and Zane had heart failure, which quickly led doctors to find the genetic blood disorder in which there's not enough hemoglobin produced to carry oxygen throughout the body.
In addition to the oxygen shortages caused by alpha thalassemia, it can also decrease patients' red blood cell count and result in anemia. In turn, that leads to pale skin, weakness, fatigue and other problems.
Fast forward to the present day, and the twins are now age 2 and in fine health.
"We are really grateful and happy," Reina told CBC News. "We didn't expect it that they [would] reach this age. They're now starting to walk and start talking ... they're eating by themselves."
Dr. Geoff Cuvelier, a hematologist and pediatric oncologist with CancerCare Manitoba, made the original diagnosis. He told CBC News that "The normal thing that would happen is that the babies would pass in utero, and they would be born a still birth."
That didn't happen, thanks in large part to Dr. Cuvelier's recommendation for the two girls to undergo blood transfusions.
"And the answer to that was they were going to give it a try," Dr. Cuvelier added. "It's very technically difficult. There are two umbilical cords, and they're very, very small. And the perinatologist needs to ... put the needle into the little umbilical vein and start transfusing these babies' blood in utero."
To avoid weekly blood tranfusions, doctors went a step further and performed a bone marrow transplant — the first time twins with the disorder had received such a procedure. Over the course of the last two years — and in spite of an initial setback in which Zoey's body rejected the first bone marrow — both twins underwent successful procedures.
"It's absolutely wonderful," Dr. Cuvelier added. "They're wonderful little kids, and they're developing just perfectly, and it's very gratifying as a physician."