Troyer syndrome (also known as spastic paraplegia gene, SPG20) belongs to a group of nervous system disorders called hereditary spastic paraplegias. The main feature of these disorders are muscle weakness and spasms in the legs that tend to get worse over time.

Troyer syndrome usually begins in early childhood. It results from a mutation in SPGP20 located in chromosome 13. The mutation causes loss of the spartin proteins.

Troyer syndrome is an autosomal recessive disorder, which means that both parents must carry it and pass on the defective gene. The disease was first observed in Amish families in Ohio. Diagnosis is made by specialized genetic testing.

In addition to muscle weakness and muscle spasms in the legs, other symptoms include:

• Permanent shortening of one or both legs
• Difficulty walking
• Speech disorders
• Drooling
• Weakening of the hand muscles
• Developmental delays
• Fluctuating emotions
• Short stature

The outlook for people with Troyer syndrome varies. Some people may have a mild form of the disease, while others eventually lose the ability to walk normally. Troyer syndrome does not shorten the normal life span.

There are no specific treatments to prevent or slow the progressive degeneration seen in Troyer syndrome. Symptomatic therapy includes antispasmodic drugs and physical therapy to improve muscle strength and maintain range of motion in the legs. Assistive devices may be needed to help with walking.

Troyer syndrome is caused by a mutation in the SPART gene. The SPART gene provides instructions for producing a protein called spartin, whose function is not entirely understood. Researchers believe that spartin may be involved in a variety of cell functions, from breaking down proteins to transporting materials from the cell surface into the cell (endocytosis). Spartin is found in a wide range of body tissues, including the nervous system.

Normal Function

The SPART gene provides instructions for producing a protein called spartin, whose function is not entirely understood. Researchers believe that spartin may be involved in a variety of cell functions, from breaking down proteins to transporting materials from the cell surface into the cell (endocytosis). Spartin is found in a wide range of body tissues, including the nervous system.

Health Conditions Related to Genetic Changes

Troyer syndrome

One mutation has been identified in people with Troyer syndrome. This mutation deletes a DNA building block (nucleotide) in the SPART gene. Specifically, this mutation deletes the nucleotide adenosine at position 1110 in the gene, written as 1110delA. This mutation results in an abnormally shortened, nonfunctioning spartin protein. It is unclear how this mutation causes the signs and symptoms of Troyer syndrome.

Other Names for This Gene

• KIAA0610
• SPARTIN
• spastic paraplegia 20
• spastic paraplegia 20 (Troyer syndrome)
• spastic paraplegia 20, spartin (Troyer syndrome)
• SPG20
• SPG20_HUMAN
• TAHCCP1
• trans-activated by hepatitis C virus core protein 1

Genomic Location

• a 25% (1 in 4) chance to be affected
• a 50% (1 in 2) chance to be an unaffected carrier like each parent
• a 25% chance to be unaffected and not be a carrier.

• Occupational therapy, assistive walking devices, and ankle-foot orthotics as needed
• Oxybutynin to reduce urinary urgency
• Antidepressants or mood stabilizers to manage emotional or mood disorders

About 20 cases of Troyer syndrome have been reported in the Old Order Amish population of Ohio. It has not been found outside this population.