The SPART gene gives the body instructions to make spartin, a protein that helps nerve cells manage and recycle materials so they can work normally. If this gene does not work properly, the nervous system can be affected, especially the long nerves that help with movement. Pathogenic variants in both copies of the SPART gene cause Troyer syndrome, which can lead to muscle stiffness, weakness, walking problems, speech differences, and short stature. SPART is mainly known in genetics rather than popular culture.
What is a gene?
A gene is a stretch of DNA that holds instructions your cells use to make molecules or direct processes in the body. Some genes carry the directions for producing proteins, the active parts of cells. Others mainly regulate when, where, and how strongly certain processes take place. Together, genes affect how the body develops and works, and they can shape how you respond to food, stress, or medications. To explore this topic in more detail, you can learn more in the LearnHub.
Overview
SPARTGene function
What if the gene works
The SPART gene helps make spartin, a protein that supports healthy mitochondria, the parts of cells that produce energy. It also helps with cell organization and movement of materials inside cells.
Risk
What if the gene does not work
Pathogenic variants in both copies of the SPART gene cause Troyer syndrome, a hereditary movement condition. People may develop leg stiffness, weakness, and walking or speech difficulties; milder and more severe variants can shape symptoms.
Treatment
What does that mean for your treatment
At present, no SPART-specific treatment or drug selection approach is established for pathogenic or loss-of-function variants in the SPART gene.
Conditions associated with SPART
Gene function
What if the gene works
Healthy cells need SPART to keep internal traffic organized and routine tasks moving smoothly. Understanding what the SPART gene does helps explain how cells sort materials, manage stored fat, and finish the last step of cell division.
The SPART gene helps cells move and recycle proteins inside small transport compartments called endosomes. This keeps important cell surface signals and membrane parts in the right place.
Its protein gathers at lipid droplets, which are tiny packets where cells store fat. There it helps control how stored fat is organized and released for everyday cell use.
SPART also supports cytokinesis (the final split that separates one cell into two). This helps each new cell finish dividing in a controlled way.
What is a variant?
A genetic variant is a minor difference in the DNA sequence within a gene. These changes are common and are part of normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many variants do not cause any noticeable effect and simply represent natural genetic variation. In some situations, though, a variant can change how a gene functions more significantly and may contribute to or directly cause a genetic condition.
Genetic variants
What if the gene does not work
People with variants in the SPART gene often make too little spartin protein or a protein that breaks down early. This is how variants in the SPART gene affect cells: they can disrupt mitochondria (the cell’s energy producers), membrane sorting, and fat droplet handling. Milder variants may leave some protein activity, while more severe variants can remove it almost completely. In Troyer syndrome, less remaining activity often tracks with earlier onset and broader movement problems.
How variants are linked to conditions
Pathogenic variants in the SPART gene cause Troyer syndrome, a rare inherited form of hereditary spastic paraplegia called SPG20. People with this condition often develop progressive leg stiffness and weakness, walking difficulties, short stature, and speech or learning differences. This SPART gene condition usually appears in childhood and is confirmed when disease-causing variants are found in both copies of the gene.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are widely seen in the general population. Most do not have a direct effect on health and simply contribute to natural human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a certain diagnosis, especially when multiple genes and environmental factors also play a role. In some situations, though, a single well-characterized variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For SPART-related conditions, risk is mainly determined by inheritance rather than lifestyle. The chance is higher when both parents carry a harmful SPART gene change, and it can also be higher in families where the parents are blood relatives. There is not enough evidence to say that diet, exercise, or other daily habits change the chance of having the condition.
Inheritance of SPART variants
For SPART-related Troyer syndrome, how variants of the SPART gene are inherited follows an autosomal recessive pattern. This means a person usually inherits one nonworking copy from each parent. Parents who each carry one SPART variant are often unaffected, and with each pregnancy there is a 25% chance of having an affected child, a 50% chance of having a child who is a carrier, and a 25% chance of having a child with two working copies of the gene. Sons and daughters are affected at the same rate.
What does my SPART result mean for my family?
For families with a disease-causing SPART result, this usually means a recessive condition, so brothers and sisters may also be affected or may be carriers even if they have no symptoms. Parents are often healthy carriers, and other relatives on either side of the family may be carriers too. Children of someone with two changed SPART copies will usually be carriers unless the other parent also carries a SPART change.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a change in the SPART gene, a lab can do genetic testing for variants in the SPART gene using a blood sample or saliva sample. The test reads the gene's DNA code and can help confirm whether a variant linked to a SPART-related condition is present, or whether a family member is a carrier.
When should I consider getting a genetic test?
Consider genetic testing for the SPART gene if someone has long-standing leg stiffness and weakness starting in childhood, often with delayed development, speech changes, or a family history of the same pattern. Testing can help confirm Troyer syndrome, a rare inherited condition linked to changes in SPART.
A genetic result is only one part of your health story
Genetic findings can provide useful insight, but how much they explain varies with the condition and the kind of variant present. Over time, the way the body functions is shaped by many factors, including lifestyle, environment, age, and medical history. For some conditions, particularly those affected by many genes, genetic information offers context rather than certainty and is most helpful when considered with the rest of a person’s care. In other situations, a genetic finding can give a clear answer. In areas like medication response, genetic results may help put individual experiences into perspective.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. This helps explain why the same drug works well for one person, has less effect in another, or causes more side effects in someone else. Small differences in how the body absorbs, breaks down, transports, or responds to a medicine are common and can shape treatment results. In practice, genetics is one part of the picture, along with age, other health conditions, and other medicines you take.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can affect a person’s response to medications. By looking at patterns between genes and drugs, it helps explain why the same treatment may work differently from one person to another. For many medicines, genes can influence both how strongly a drug works and how the body processes it. This information can support treatment decisions that are more informed and more individualized. You can read more about this topic in the LearnHub.
Drugs influenced by the SPART gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medicine choice or dose, so general questions about symptoms, side effects, or how treatments may affect you are best discussed with your doctor.
History
SPART entered the medical literature through studies of Troyer syndrome, a rare inherited condition first described in Old Order Amish families in the 1960s. The condition took its name from the Troyer surname seen in some of the earliest reported families. Initially understood only through visible traits, later recognized as tied to a specific gene, it was mapped to chromosome 13 before researchers identified variants in the SPART gene as the cause in the late 1990s and early 2000s. From these first observations, research expanded steadily. Later work showed that SPART-related disease was not limited to the Amish community, and affected families were identified in other populations as genetic testing became more widely available.