Is this common?

Dopamine deficiency syndrome is a rare hereditary condition that has only 20 confirmed cases. It’s also known as dopamine transporter deficiency syndrome and infantile parkinsonism-dystonia.

This condition affects a child’s ability to move their body and muscles. Although symptoms typically appear during infancy, they may not appear until later in childhood.

Symptoms are similar to those of other movement disorders, such as juvenile Parkinson’s disease. Because of this, it’s often misdiagnosed. Some researchers also think that it’s more common than previously thought.

This condition is progressive, which means it worsens over time. There is no cure, so treatment focuses on managing symptoms.

Keep reading to learn more.

What are the symptoms?

Symptoms are usually the same regardless of the age that they develop. These may include:

  • muscle cramps
  • muscle spasms
  • tremors
  • muscles moving very slowly (bradykinesia)
  • muscle stiffness (rigidity)
  • constipation
  • difficulty eating and swallowing
  • difficulty speaking and forming words
  • problems holding the body in an upright position
  • difficulties with balance when standing and walking
  • uncontrollable eye movements

Other symptoms may include:

  • gastroesophageal reflux disease (GERD)
  • frequent bouts of pneumonia
  • difficulty sleeping

What causes this condition?

According to the U.S. National Library of Medicine, this genetic disorder is caused by mutations to the SLC6A3 gene. This gene is involved in the creation of the dopamine transporter protein. This protein controls how much dopamine is transported from the brain into different cells.

Dopamine is involved in everything from cognition and mood, to the ability to regulate body movements. If the amount of dopamine in the cells is too low, it can affect muscle control.

Who’s at risk?

Dopamine deficiency syndrome is a genetic disorder, meaning a person is born with it. The main risk factor is the genetic makeup of the child’s parents. If both parents have one copy of the mutated SLC6A3 gene, their child will receive two copies of the altered gene and inherit the disease.

How is it diagnosed?

Oftentimes, your child’s doctor can make a diagnosis after observing any challenges they may have with balance or movement. The doctor will confirm the diagnosis by taking a blood sample to test for the condition’s genetic markers.

They may also take a sample of cerebrospinal fluid to look for acids related to dopamine. This is known as a neurotransmitter profile.

How is it treated?

There isn’t a standardized treatment plan for this condition. Trial and error is often necessary to determine which medications can be used for symptom management.

Researchers have had more success in managing other movement disorders related to dopamine production. For example, levodopa has been successfully used to relieve symptoms of Parkinson’s disease.

Ropinirole and pramipexole, which are dopamine antagonists, have been used to treat Parkinson’s disease in adults. Researchers have applied this medication to dopamine deficiency syndrome with some success. However, more research is needed to determine the potential short- and long-term side effects.

Other strategies for treating and managing symptoms are similar to that of other movement disorders. This includes medication and lifestyle changes to treat:

How does it affect life expectancy?

Infants and children with dopamine transporter deficiency syndrome may have a shorter life-span. This is because they’re more susceptible to life-threatening lung infections and other respiratory illnesses.

In some cases, a child’s outlook is more favorable if their symptoms don’t appear during infancy.