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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Spastic paraplegia type 3A

Reviewed January 2008

What is spastic paraplegia type 3A?

Spastic paraplegia type 3A is part of a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by progressive muscle stiffness (spasticity) and the development of paralysis of the lower limbs (paraplegia). Hereditary spastic paraplegias are divided into two types: pure and complex. The pure types involve only the lower limbs, whereas the complex types also involve the upper limbs (to a lesser degree) and the nervous system. Spastic paraplegia type 3A is a pure hereditary spastic paraplegia.

In addition to the usual muscle stiffness and weakness characteristic of the hereditary spastic paraplegias, people with spastic paraplegia type 3A can also experience progressive muscle wasting (amyotrophy) in the lower limbs, reduced bladder control, and an abnormal curvature of the spine (scoliosis). The signs and symptoms of spastic paraplegia type 3A usually appear in the first decade of life. The condition progresses very slowly, and some people may need walking support late in life.

How common is spastic paraplegia type 3A?

Symptoms of spastic paraplegia type 3A commonly appear before the age of 10. The specific incidence of this disorder is unknown.

What genes are related to spastic paraplegia type 3A?

Mutations in the ATL1 gene cause spastic paraplegia type 3A. The ATL1 gene provides instructions for producing a protein called atlastin-1. Atlastin-1 is found throughout the body, particularly in the brain. In cells, this protein is found in structures known as the endoplasmic reticulum and the Golgi apparatus, which are involved in the movement of proteins and cell components within the cell.

Atlastin-1 likely plays a role in the transportation of cell components and in the formation of the endoplasmic reticulum and Golgi apparatus, each of which is involved in the growth of axons (specialized extensions of nerve cells that transmit nerve impulses). Atlastin-1 is necessary for the formation and growth of axons; however, its precise function remains unclear. Researchers suggest that mutations in atlastin-1 cause the signs and symptoms of spastic paraplegia type 3A by interfering with the protein's role in axonal growth.

Related Gene(s)

Changes in this gene are associated with spastic paraplegia type 3A.

  • ATL1

How do people inherit spastic paraplegia type 3A?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

Where can I find information about diagnosis or management of spastic paraplegia type 3A?

These resources address the diagnosis or management of spastic paraplegia type 3A and may include treatment providers.

  • Gene Review: Hereditary Spastic Paraplegia Overview (
  • Gene Review: Spastic Paraplegia 3A (
  • Genetic Testing Registry: Spastic paraplegia 3 (
  • Spastic Paraplegia Foundation, Inc.: Treatments and Therapies (

You might also find information on the diagnosis or management of spastic paraplegia type 3A in Educational resources ( and Patient support (

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about spastic paraplegia type 3A?

You may find the following resources about spastic paraplegia type 3A helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for spastic paraplegia type 3A?

  • Hereditary Autosomal Dominant Spastic Paraplegia
  • Hereditary Spastic Paraplegia
  • spastic paraplegia 3
  • spastic paraplegia 3A
  • SPG3A

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about spastic paraplegia type 3A?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding spastic paraplegia type 3A?

autosomal ; autosomal dominant ; axons ; cell ; endoplasmic reticulum ; gene ; Golgi apparatus ; hereditary ; incidence ; inherited ; nervous system ; paraplegia ; protein ; scoliosis ; spasticity ; wasting

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (


  • Ivanova N, Claeys KG, Deconinck T, Litvinenko I, Jordanova A, Auer-Grumbach M, Haberlova J, Löfgren A, Smeyers G, Nelis E, Mercelis R, Plecko B, Priller J, Zámecník J, Ceulemans B, Erichsen AK, Björck E, Nicholson G, Sereda MW, Seeman P, Kremensky I, Mitev V, De Jonghe P. Hereditary spastic paraplegia 3A associated with axonal neuropathy. Arch Neurol. 2007 May;64(5):706-13. (
  • Namekawa M, Ribai P, Nelson I, Forlani S, Fellmann F, Goizet C, Depienne C, Stevanin G, Ruberg M, Dürr A, Brice A. SPG3A is the most frequent cause of hereditary spastic paraplegia with onset before age 10 years. Neurology. 2006 Jan 10;66(1):112-4. (
  • Reid E. Science in motion: common molecular pathological themes emerge in the hereditary spastic paraplegias. J Med Genet. 2003 Feb;40(2):81-6. Review. (
  • Zhu PP, Soderblom C, Tao-Cheng JH, Stadler J, Blackstone C. SPG3A protein atlastin-1 is enriched in growth cones and promotes axon elongation during neuronal development. Hum Mol Genet. 2006 Apr 15;15(8):1343-53. Epub 2006 Mar 14. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: January 2008
Published: March 2, 2015