PAYSON, Ill. -- Like any parent, Mercedes Boden, 29, dreams of a future for her 4-year-old son Jaxtien.
She and her fiance, Damien Miller, dream of seeing the couple's child pedal away from the couple's home in Payson toward the nearby Ken Morgan Memorial Park to play with friends.
"That is the ultimate dream. That is the kind of future that we pray for. That is the Jaxtien I dream about," Damien said.
The simple act of pedaling a bicycle, or even walking to the nearby park, may seem like a routine thing for just about any child, but they are not simple for Jaxtien, who was diagnosed earlier this year with a rare hereditary disease known as metachromatic leukodystrophy, which has affected the boy's ability to walk or climb stairs.
According to the National Institutes for Health, metachromatic leukodystrophy, or MLD, is a condition where there is an accumulation of fats called sulfatides in the cells. This accumulation especially affects cells in the nervous system that produce myelin, the substance that insulates and protects the nerves.
The accumulation of sulfatides in myelin-producing cells causes a destruction throughout the body's nervous system, including the brain and spinal cord and the nerves connecting the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat and sound.
People with MLD suffer from a variety of symptoms, including the loss of intellectual functions and motor skills, such as the ability to walk. Other symptoms include incontinence, seizures, paralysis, an ability to speak, blindness and hearing loss. As the disease progresses, those with MLD will lose awareness of their surroundings and become unresponsive.
The most common form of MLD is classified as late infantile because the initial wave of symptoms begin appearing in the second year of life. Those with the late infantile form of MLD typically do not survive past age 10.
The second most common form of MLD is classified as juvenile because the symptoms arrive between age 4 and adolescence. Researchers with the National Institutes for Health say the disease moves more slowly in this form, and those affected may survive for about 20 years after diagnosis.
The third form of MLD is the adult form, where first symptoms appear during teenage years or later. While the disease remains fatal, those who are diagnosed with it as adults tend to live about 20 or 30 years after the diagnosis.
Dean Suhr, president and co-founder of the MLD Foundation, said Jaxtien falls in a "gray area between late infantile and juvenile," which means doctors and researchers don't know what kind of life expectancy Jaxtien has. ?Jaxtien's first symptoms began to appear last year, but he was not diagnosed until earlier this year.
The fear of losing her youngest son is enough to make the eyes of Mercedes, a stay-at-home mother, fill with tears. She says since his diagnosis in July she has not allowed herself to dwell on the idea that her son's life may be cut short because of a gene that she and Damien both have.
"As a mother, I feel so helpless," Mercedes said.
"Mothers are supposed to kiss boo-boos, to heal what hurts, but with this disease, I can't do that. I can't do my job as a mother, and that is terrifying."
Mercedes' older son, Gabrien, 11, has not displayed symptoms of MLD. He will be tested at a later date. Gabrien's father is believed to not carry the disease.
MLD is rare, reportedly only being diagnosed in 1 in 40,000 to 160,000 people worldwide. The condition is more common among certain ethnic groups, such as Jewish people from southern Arabia, members of the Navajo tribe, and Arab groups living in Israel.
Treating the disease is even more complex, as Suhr said there is no known cure, only treatments that will slow the disease's progression. Suhr lost two daughters to the disease.
Finding doctors knowledgeable about the disease is even more difficult. The family traveled to Italy earlier this year, on a trip paid for by a pharmaceutical company, to see if Jaxtien met the criteria to participate in the company's clinical trial there. He was rejected.
"We begged Italy to reconsider," Mercedes said. As Jaxtien's parents have found out, only three hospitals in the country, including physicians at the University of Pittsburgh Medical Center's Children's Hospital, are believed to be experienced in treating MLD.
Doctors there hope to give Jaxtien a stem cell transplant using donor cells from umbilical cords. If Jaxtien proves to be a good candidate, he will go through a series of tests, and his parents must decide if they want to move forward with a risky procedure. The transplant carries risk such as death and disability.
However, before he can receive the donor cells, he must first go through an extensive chemotherapy treatment that will significantly weaken his immune system. Because of this weakened state, Jaxtien will live in isolation for several weeks.
Damien said, "We explored every option." He has taken an extended leave of absence from his job as a mechanic at Shottenkirk Kia in Quincy. "It is scary because of the process of the transplant. It is scary because as a parent, you are just hoping to give Jaxtien the best shot at living a normal life. I feel like this is his best shot."
If the transplant is a success, Suhr said the hope is that Jaxtien's cognitive abilities are preserved and that any decline of his physical abilities such as walking are stalled.
In the meantime, Jaxtien's parents say they hope he continues to live life unaware of the potentially grim circumstances he faces.
"He has no limitations right now," Damien said. "Right now, we let him be a kid."
A kid who can spend hours playing on the carpeted floor of his family's home, building a zoo with his toy animals.
A kid who loves swimming and camping, riding in his Power Wheels vehicle in circles around the family's home.
A kid who begged his dad to teach him to ride a bike with training wheels.
"What is important to us is that he continues to live each day with joy and happiness," Mercedes said. "That's my hope."