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Troyer syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Troyer syndrome

Troyer syndrome is a rare, complex form of hereditary spastic paraplegia characterized by progressive stiffness and weakness of the leg muscles, along with other symptoms like developmental delays and muscle wasting, typically beginning in early childhood.

Overview

Troyer syndrome is a type of hereditary spastic paraplegia, also called hereditary spastic paraparesis. Hereditary spastic paraplegias are a group of genetic disorders characterized by progressive stiffness (spasticity) and weakness of the leg muscles. The degree of leg weakness in people with hereditary spastic paraplegia can vary. Paraparesis is the term used to describe leg weakness, while paraplegia refers to severe weakness of the leg muscles.

Hereditary spastic paraplegias are divided into two types: pure and complex (sometimes called uncomplicated and complicated). The pure types of hereditary spastic paraplegia involve the legs and the bladder. Complex hereditary spastic paraplegias may include additional signs and symptoms such as intellectual disabilities, problems with coordination and balance (ataxia), and damage to the nerves that connect and spinal cord to the rest of the body (peripheral neuropathy). Troyer syndrome is a complex hereditary spastic paraplegia.

People with Troyer syndrome can experience a variety of signs and symptoms. These health problems typically begin in early childhood and slowly worsen over time. Common features of Troyer syndrome include delays in learning to walk and talk, progressive weakness and spasticity of the leg muscles, muscle wasting in the hands and feet (distal amyotrophy), and short stature. Affected individuals may also have speech difficulties (dysarthria), skeletal (bone) abnormalities, and mood swings.

Troyer syndrome causes the breakdown (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 decline in muscle and nerve function. Most affected individuals require wheelchair assistance by the time they are in their 50s or 60s. Troyer syndrome generally does not affect a person's life expectancy.

Frequency

Around 40 cases of Troyer syndrome have been reported. This condition was first recognized in the Old Order Amish population of Ohio. It has since been found in other populations.

Causes

Some variants (also called mutations) in the SPART gene have been found to cause Troyer syndrome. The SPART gene provides instructions for producing a protein called spartin. Spartin is found in a number of body tissues, including the brain. Researchers believe that spartin may be involved in regulating the size and number of lipid droplets inside the cell. Specifically, spartin may be involved in delivering lipid droplets to the cell's recycling center. Lipid droplets help cells use and store fats, which are an important energy source.

Spartin also plays a role in other cell activities. Spartin may play a role in regulating the activity of endosomes, which are structures inside the cell that are involved in sorting, transporting, and recycling proteins and other materials. Spartin may also play a role in mitochondrial function. Mitochondria are the energy-producing centers inside the cell.

The variants that cause Troyer syndrome reduce the amount of functioning protein inside the cell. Cells that do not have enough normal spartin cannot break down lipid droplets properly, which allows fat molecules to build up inside the cell. Researchers are investigating how variants in the SPART gene cause the specific signs and symptoms of Troyer syndrome.

Gene Associated with Troyer Syndrome

  • SPART

Inheritance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell must have a variant to cause the disorder. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they typically do not show signs and symptoms of the condition.

Other Names

  • Autosomal recessive spastic paraplegia type 20
  • Spastic paraparesis, childhood-onset, with distal muscle wasting
  • Spastic paraplegia 20, autosomal recessive
  • Spastic paraplegia, autosomal recessive, Troyer type
  • SPG20

Frequently Asked Questions

Parents might first notice delays in their child reaching developmental milestones, such as learning to walk or talk. Other early indicators can include a subtle stiffness or awkwardness in their legs, or difficulty with fine motor skills in their hands, which may progress to visible muscle wasting in these areas.
Troyer syndrome is inherited in an autosomal recessive pattern. This means that a child must inherit two copies of the altered gene (one from each parent) to develop the condition. If both parents are carriers, there is a 25% chance with each pregnancy that their child will be affected, a 50% chance the child will be a carrier, and a 25% chance the child will not be affected and not be a carrier. Genetic counseling can help families understand these risks.
Troyer syndrome is a progressive condition, meaning symptoms slowly worsen over time, typically starting in early childhood. Individuals will experience increasing leg weakness and stiffness, which can eventually impact their ability to walk independently. Developmental delays can persist, and some may experience intellectual disabilities. The severity and rate of progression can vary, but ongoing support and adaptations are usually needed to manage daily activities as the condition advances.
Management focuses on supportive therapies to improve quality of life and function. This often includes physical therapy to help maintain muscle strength and flexibility, occupational therapy for daily living skills, and speech therapy for communication difficulties. Orthopedic interventions may be needed for skeletal abnormalities, and medications can help manage spasticity or mood swings. Regular monitoring by a neurologist and other specialists is crucial.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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