Mary Beth Thistle was just six months old when she had her first seizure and her family embarked on a medical journey that included a diagnosis of a disease so rare, the number of people who have it in Newfoundland and Labrador can be counted on a single hand.

"It must have been at least 23 minutes long," her mother, Patti Bryant, said as she recounted the experience.

"It was full grand mal seizure on the whole left side," Bryant said. "And then a month later, she did have the same on the right hand side, and it was about 26 minutes long."

Mary Beth, who is now 19, has Dravet Syndrome, a genetic disorder that causes catastrophic epilepsy, resulting in physical and intellectual impairment. It can also cause other neurological and developmental problems.

Patti Bryant says her daughter Mary Beth has suffered up to 20 seizures a night. (CBC)

It's estimated that 100 Canadians suffer from the disorder. Only five of them live in Newfoundland and Labrador.

But the consequences of rare diseases are more common than people may think, and collectively affect close to 10 per cent of the world's population. This Saturday, Rare Disease Day will be marked around the world.

Living with a rare disease is something Mary Beth's family has learned a lot about.

She's been at death's door, oh, several times. She died in my arms four times, and in other people's more times. - Patti Bryant

Bryant said Mary Beth has suffered up to 20 seizures a night, each one robbing her daughter of another skill.

"She's been at death's door, oh, several times. She died in my arms four times, and in other people's more times," she said.

"Last year we were having troubles for a few days ... she couldn't come down the stairs. And I finally figured out that she was trying to put both feet down the stairs, because she was going with an old piece of information that the left foot had to go, but she was still working with the current information that the right foot had to go,"

Seizures generally start within a child's first year of life.

Bryant noticed physical deficits when Mary Beth was about two and and a half, adding they were "lucky" to have had her diagnosed by a neurologist before the age of five.

"Up until she was two years of age, she hit or exceeded all her milestones," said Bryant.

Bryant said Mary Beth's cognitive deficits and intellectual delays were obvious by the time she reached the age of four and a half.

Mary Beth currently has the verbal ability of a four-year old child, and her speech is limited to about 400 words.

Better seizure control

Dravet Syndrome was only recently identified. Bryant said it is still poorly understood, with each case requiring its own cocktail of drugs and therapies, and often just guess work.

Patti Bryant says her daughter Mary Beth Thistle, 19, has had seizures since she was six months of age. (CBC)

Bryant said the use of medical marijuana in the past has been incredibly effective, in decreasing the number of seizures Mary Beth has on a monthly basis.

On average, Bryant said her daughter will have 50 seizures in any given month, although with medical marijuana, the number of seizures has dropped to less than 20 per month, and in some months there were none.

Bryant said during that time, Mary Beth was happier, and able to "do more."

In 2012, Bryant, another parent and a researcher established a website, due to a lack of information available on Dravet Syndrome.

The website is a pan-Canadian support network for families, friends and caregivers of those with Dravet spectrum disorders.

"So, we all work together. We all share our information together," Bryant said.

Bryant, who has been a longtime volunteer with Epilepsy NL, was honoured last year by Memorial University and given the President's Award for exceptional community service.