Welcome to Troyer Syndrome / SPG20 page

What is Troyer Syndrome / SPG20?

Troyer disorder is observed first time by Cross and McKusick (1967) in an Amish group in Ohio. Troyer is named to the surname of many of the affected persons.

Troyer syndrome is one of the many disorders belonging to the group Hereditary Spastic Paraplegias and is "autosomal recessive"  inherited.

The HSP disorders are characterized by progressive muscle stiffness (spasticity) and the development of paralysis of the lower limbs (paraplegia). 

There are two main types of HSP :

  • I- Pure type involves the lower limbs.

  • II- Complex types involve the lower limbs and can also affect 
- the upper limbs to a lesser degree; 
- the structure or functioning of the brain; 
- and the nerves connecting the brain and spinal cord to muscles 
- and sensory cells that detect sensations such as touch, pain, heat, and sound (the peripheral nervous system). 

Troyer syndrome is a complex hereditary spastic paraplegia.

People with Troyer syndrome may have variety of the following signs and symptoms. 

- spasticity of the leg muscles, 
- progressive muscle weakness, 
- paraplegia, 
- muscle wasting in the hands and feet (distal amyotrophy), 
- small/short stature, 
- developmental delay, 
- learning disorders (lower VIQ and PIQ), 
- speech difficulties (dysarthria), 
- mood swings, unpredictable sometime reasonless up & down with emotions
- exaggerated reflexes (hyperreflexia) in the lower limbs, 
- uncontrollable movements of the limbs, 
- skeletal abnormalities, 
- bending outward of the knees.

Troyer syndrome causes the degeneration and death of muscle cells and motor neurons (specialized nerve cells that control muscle movement) throughout a person's lifetime, leading to a slow progressive decline in muscle and nerve function.  The severity of impairment increases as a person ages. Most affected individuals require a wheelchair by the time they are in their fifties or sixties.

Until know there are about 30 cases of Troyer syndrome have been reported around world, so far as known 20 Old Order Amish population of Ohio, 2 Philippins, 2 Turkish, 2 Omani's and 1 Saudi families have not been found outside this population

The Troyer is an autosomal recessive inherited disorder, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.