New on the MedlinePlus Autoimmune Diseases page:
10/28/2014 11:30 PM EDT
Source: National Library of Medicine -
STING-associated vasculopathy with onset in infancy
(often shortened to SAVI)
On this page:
Reviewed October 2014
What is SAVI?
STING-associated vasculopathy with onset in infancy (SAVI) is a disorder involving abnormal inflammation throughout the body, especially in the skin, blood vessels, and lungs. Inflammation normally occurs when the immune system sends signaling molecules and white blood cells to a site of injury or disease to fight microbial invaders and help with tissue repair. Excessive inflammation damages the body's own cells and tissues. Disorders such as SAVI that result from abnormally increased inflammation are known as autoinflammatory diseases.
The signs and symptoms of SAVI begin in the first few months of life, and most are related to problems with blood vessels (vasculopathy) and damage to the tissues that rely on these vessels for their blood supply. Affected infants develop areas of severely damaged skin (lesions), particularly on the face, ears, nose, fingers, and toes. These lesions begin as rashes and can progress to become wounds (ulcers) and dead tissue (necrosis). The skin problems, which worsen in cold weather, can lead to complications such as scarred ears, a hole in the tissue that separates the two nostrils (nasal septum perforation), or fingers or toes that require amputation. Individuals with SAVI also have a purplish skin discoloration (livedo reticularis) caused by abnormalities in the tiny blood vessels of the skin. Affected individuals may also experience episodes of Raynaud phenomenon, in which the fingers and toes turn white or blue in response to cold temperature or other stresses. This effect occurs because of problems with the small vessels that carry blood to the extremities.
In addition to problems affecting the skin, people with SAVI have recurrent low-grade fevers and swollen lymph nodes. They may also develop widespread lung damage (interstitial lung disease) that can lead to the formation of scar tissue in the lungs (pulmonary fibrosis) and difficulty breathing; these respiratory complications can become life-threatening. Rarely, muscle inflammation (myositis) and joint stiffness also occur.
How common is SAVI?
The prevalence of this condition is unknown. Only a few affected individuals have been described in the medical literature.
What genes are related to SAVI?
SAVI is caused by mutations in the TMEM173 gene. This gene provides instructions for making a protein called STING, which is involved in immune system function. STING helps produce beta-interferon, a member of a class of proteins called cytokines that promote inflammation.
The TMEM173 gene mutations that cause SAVI are described as "gain-of-function" mutations because they enhance the activity of the STING protein, leading to overproduction of beta-interferon. Abnormally high beta-interferon levels cause excessive inflammation that results in tissue damage, leading to the signs and symptoms of SAVI.
Read more about the TMEM173 gene.
How do people inherit SAVI?
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. In most cases, this condition likely results from new (de novo) mutations in the gene that occur during the formation of reproductive cells (eggs or sperm) or in early embryonic development. These cases occur in people with no history of the disorder in their family.
Where can I find information about diagnosis or management of SAVI?
These resources address the diagnosis or management of SAVI and may include treatment providers.
- Beth Israel Deaconess Medical Center: Autoinflammatory Disease
- Genetic Testing Registry: STING-ASSOCIATED VASCULOPATHY,
- University College London: Vasculitis and Autoinflammation Research
You might also find information on the diagnosis or management of SAVI in Educational resourcesand 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 SAVI?
You may find the following resources about SAVI 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 SAVI?
- STING-associated vasculopathy, infantile onset
What if I still have specific questions about SAVI?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
- What does it mean if a disorder seems to run in my family?
- What are the different ways in which a genetic condition can be inherited?
- If a genetic disorder runs in my family, what are the chances that my children will have the condition?
- Why are some genetic conditions more common in particular ethnic groups?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding SAVI?
autosomal ; autosomal dominant ; cell ; class ; embryonic ; fibrosis ; gene ; immune system ;inflammation ; inherited ; injury ; joint ; lymph ; necrosis ; prevalence ; protein ; pulmonary ;reproductive cells ; respiratory ; septum ; sperm ; tissue ; white blood cells
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (9 links)
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.