A London family is living with a rare genetic disease that strikes children, and it has affected not just one but two of their three kids.

There's no cure, but the family’s story of courage and strength truly shows the power of love.

Young Rey's world is one of constant care and vigilance.

His father David Alsemgeest says “Rey is 100 per cent non-communicative. He can't do anything besides experience the world that comes to him.”

Rey is blind and can't eat or move without help. The neurodegenerative disorder Batten Disease has robbed him of those abilities.

"It's extremely sad to have to see my boy go through this every day…at this point his eighth birthday could indeed be his last. The average lifespan of children with this disease is anywhere between eight and 12 years old.”

Rey was a healthy and active little boy until the early signs of Batten appeared, starting with problems with balance.

"Basically the body is not able to process some of the fatty acids,” Alsemgeest says. “I liken it to either Alzheimer’s, or something that destroys the brain."

After his parents learned of Rey's diagnosis, there was more heartbreak. Rey's little sister, four-year-old Mei is also fighting Batten Disease.

"That was really heartbreaking, especially for [my wife] Katsumi because she really wanted to have a daughter. And the daughter that we do have unfortunately won't live probably past her tenth birthday.”

Batten Disease is rare, affecting 2-4 of every 100,000 births. While it is known to be genetic in origin there is currently no cure.

Rey and Mei also have an older brother, but 12-year-old Ken is not affected by Batten, not physically at least. Alsemgeest says "Ken's been amazing.”

Fighting the disease is a 24-hour-a-day battle for the family, and Alsemgeest says “This disease it really has cost us so much, including my job."

In the distant future geneticists like Dr. Chitra Prasad, an associate professor at the London Health Sciences Centre, say there's hope through medical research.

"The gene therapy trials are going on. But it is still early. People are also looking at stem cells."

For this family time is marked in days and months, and all of that time is precious.

"Strength comes from our children,” Alsemgeest says, “just trying to be with them one more day."