When Marian McGlocklin was born in late 2015, her parents Paul and Sara knew something wasn't right.
Her legs were very thin, her cries weren't loud, and her milestones were delayed.
They spent a year and four months pursuing tests and doctors exams, the Daily Mail reported.
But their suspicions could never have prepared them for her diagnosis: childhood Alzheimer's.
The progressive, fatal condition, officially known as Niemann-Pick disease type C, causes enlarged organs, lung damage, muscle stiffness, dementia and difficulty speaking.
It affects just 500 children worldwide. In most cases, symptoms appear around the age of four. Sufferers rarely live past the age of 10.
There is hope for Marian in the form of a new clinical trial that has developed a drug to stabilize children in decline and halt the disease's progression.
The parents of the 19-month-old, from Los Angeles, California, have spoken to Daily Mail Online about their race against time to find treatment before the disease robs Marian of her speech and mobility - and kills her.
Paul and Sara, who also have a 4-year-old daughter named Emily, received nothing concrete until shortly after Marian's first birthday in September 2016.
'We saw that she wasn't reaching her milestones on time,' Sara told Daily Mail Online.
"You know, we were like, "Oh she's not holding her head up. She's not reaching for a toy. She's not holding eye contact".
"And then every time we were at the brink of worrying, she'd reach the milestone so we just thought she had a learning delay."
Doctors at Children's Hospital Los Angeles detected an enlarged spleen, combined with ongoing, mild muscle weakness.
For five months, they visited a number of specialists - a hematologist, a gastroenterologist, a geneticist, and a neurodiagnostician - and ordered a battery of tests.
Finally, this February, the McGlocklins received a diagnosis of Niemann-Pick disease type C (NPC).
NPC is a rare, progressive genetic disorder, which is characterised by an inability of the body to metabolise cholesterol and other fatty substances (lipids) inside of cells.
This causes enlarged organs, lung damage, and slow and steady neurological deterioration, in the form of dementia.
The muscles will begin to stiffen to the point where patients are unable to walk.
Speech becomes more difficult until sufferers are unable to talk, or even breathe, before eventually succumbing to the disease.
Only 500 children in the world have been diagnosed - and there was a one in 150,000 chance that Marian would have the disease.
"It was horrible, it was kind of my worst fear," Sara said.
"I was upstairs and I could hear the girls playing and laughing with the babysitter and it was just so difficult to comprehend and face.
"How do you go grocery shopping with this happening? How do you go about your day worried that your child might die?"
And doctors told her parents there was a 25 per cent chance that their 4-year-old daughter, Emily, might have NPC too - but her results came back negative.
Over half of children diagnosed die by age 10 without intervention.
However, weeks after Marian's diagnosis, the family learned that a clinical trial could stabilize - and even halt - the disease's progression.
Cyclodextrin (or VTS 270) has been tested. In lab trials on mice, it extended sufferers' lives five-fold.
The drug has now reached Phase II/III trials on humans.
VTS 270 is a sugar compound found in fat-free dressings and margarine.
It appears to stabilise children in decline and substantially halt NPC's progression, something which seemed scientifically impossible only a few years ago.
Currently, VTS 270 can only be administered via spinal tap under anesthesia in a hospital every two weeks, indefinitely, and the treatment is only available in Chicago, Illinois.
While Marian is too young to be enrolled in the trial - participants have to be four years old or older - she is eligible for compassionate use.
This occurs when seriously ill patients are treated using a new, unapproved drug when no other treatments are available.
Marian's use of VTS 270 begins on Monday. For the indefinite future, she will be travelling back and forth from California to Illinois for treatment.
The family has set up a Facebook page to document Marian's journey as well as a GoFundMe to cover medical expenses. Out of their $150,000 goal, more than $57,000 has been raised.
Genetic researchers say this type of family-driven funding is what is pushing progress towards finding a cure.
"Doctors have told me that they think NCP will be like cystic fibrosis where, you know, in the last 20 years, the life expectancy has tripled," Sara said.
"But Marian could start declining in 10 years, five years or tomorrow. So we wonder if that increased life expectancy will be at the beginning, at the middle or at the end of her journey.
"Will it happen in time for Marian? And I hope that it will."