A 3-year-old boy in the U.K. has lost his ability to walk and talk after he was diagnosed with a rare genetic condition, called metachromatic leukodystrophy (MLD). The debilitating condition causes early-onset dementia, which is otherwise associated with the elderly.

MLD is a rare disorder that gradually progresses and affects the functioning of the nervous system and brain. The condition is caused by the lack of an enzyme, arylsulfatase A (ARSA), which results in the build-up of sulfatides in the body. The chemical damage caused by the missing enzyme affects sheaths that surround nerves and damages the nervous system, kidneys, gallbladder and other organs.

Joey Walton from West Yorkshire, England, was diagnosed with late-infantile MLD when he was 18 months old. Walton lost his ability to walk and talk. The condition could cause muscle wasting, weakness, loss of vision, issues with swallowing, paralysis and dementia.

Doctors say Walton has grim chances of survival beyond the age of seven.

"If it's picked up early, treatment is available. It's too late for Joey, but if we can stop more families going through this agony, it's worth it," Katie, the boy's mother, said.

Know more about MLD

MLD occurs when a mutated gene is inherited from both biological parents. It affects one in every 40,000 people in the United States. Apart from dementia, the condition causes malnutrition, blindness, aspiration pneumonia and death.

There are three types of MLD:

1. Late infantile MLD: This is the most common type of MLD that affects children between the ages of 12 and 20 months. The condition causes walking issues, developmental delays, blindness and dementia. The majority of the children with late infantile MLD die by age 5.

2. Juvenile MLD: This is the type of MLD that affects 20 to 30% of people. The deterioration starts between the ages of 3 and 10 and can lead to cognitive decline, behavioral difficulties, seizures and dementia. The patients are expected to die within 10 to 20 years after the diagnosis.

3. Adult MLD: This type of MLD begins after the age of 16. The patients develop psychiatric issues, seizures and dementia. The average expected life expectancy is six to 14 years after the diagnosis.

Diagnosis and treatment

MLD is diagnosed through blood tests, urine tests and brain MRI (magnetic resonance imaging). Currently, there is no cure for the condition. The treatment involves medications to control symptoms such as digestive issues, pain and seizures and supportive care such as speech therapy and physical therapy. In some children, umbilical cord blood transplant is a treatment option to reduce disease progression.