For Reed Havlik, a 6-year-old boy from Iowa, the excitement and thrill of events like Halloween are literally a matter of life and death.

He is one of fewer than 200 people worldwide with leukodystrophy, a type of incurable, inherited neurological disease that causes progressive destruction of the neurons in the central nervous system. Also referred to as vanishing white matter disease, the condition can arise from a number of mutations in genes involved in the formation or maintenance of myelin sheaths, the lipid-rich wrappings that coat the length of many axons like beads on a string. The distinctive pale color of myelin makes the brain’s inner, axon-dense tissue visually discernable from the darker outer layers composed mostly of neuron cell bodies, hence the categories of ‘white matter’ and ‘gray matter’.  

According to the National Institutes of Health’s Genetics Home Reference, the axon loss induced by some forms of leukodystrophy can be exacerbated by physiological stress from infection, mild head trauma, and even extreme fright.

"We have got to be really careful what we expose him to because he could be frightened to death," Erika Havlik, Reed’s mother, told Fox News. "We do celebrate Halloween but only on a really small scale. Reed is going to be Mickey Mouse this year. His school throws a party which everyone dresses up for but everyone there is super helpful.”

"They make sure that the costumes aren't too scary," she said. "They really do understand how serious it is for him."

The University of Iowa Stead Family Children’s Hospital, where Reed was diagnosed back in 2014, reports that the boy will experience a gradual loss of motor control and the ability to speak, hear, and see in the coming years. He will eventually fall into a coma before he passes away.

Prior to his first visit to the hospital at age two, Reed was a seemingly healthy and happy child who had hit all his developmental milestones. Then, one day in November, Reed woke up from a nap and could no longer bear any weight on his right leg. Worried that he may have broken a bone, Erika and Jesse Havlik, Reed’s father, rushed him to a local urgent care. Unable to determine what was wrong, the family was referred to the University of Iowa hospital, where experts eventually identified leukodystrophy. He has not been able to walk since.

“As they (the doctors) described it, each piece they said got worse and worse,” Jesse said in a feature article by the hospital. “By the end of the conversation, it finally hits you that he’s going to die.”

A full genetic analysis then narrowed the diagnosis down to one of the 23-odd types of leukodystrophy currently known to science.

“Reed’s diagnosis has taught us to appreciate the moment, to be a family…and make sure we spend as much time together as we can, because we don’t know what tomorrow is going to bring with this disease,” Erika added. “We just have to keep Reed happy and moving forward, getting the help he needs and the therapies he needs so he can live as normal as he can for as long as he can.”

Currently, Reed is in a wheelchair after his condition deteriorated quickly when he came down with the flu last year. Despite the grim prognosis, she and Jesse remain optimistic, bringing Reed on as many adventures as possible and working to raise money to help further research into leukodystrophy treatments.

[H/T: Livescience]