Aicardi-Goutieres Syndrome

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There are seven different genes associated with Aicardi-Goutieres Syndrome, mutations of any of these could lead to the condition and symptoms described. These are TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1 and IFIH1. Mutations in these genes cause an increase in the production of a chemical called interferon which is thought to play a central role in the brain injury that occurs in AGS.

Mutations in these genes may sometimes cause neurological conditions that are different from AGS and that do not primarily affect the white matter of the brain.

Aicardi-Goutieres Syndrome is an extremely rare disorder. Its exact prevalence is not known, however around 120 cases have been reported.

Aicardi Goutieres syndrome (AGS) usually presents at birth or in the first year of life although later onset may occur. Those presenting at birth usually have the most severe symptoms with neurological abnormalities, a skin rash, enlarged liver and spleen and a fever.

Alternatively there may be a period of normal development followed by a rapid onset of irritability, regression of development, epileptic seizures, feeding difficulties and fever. There is usually a period of several months of extreme irritability and the onset of neurological abnormalities such as stiffness and spasticity of the arms and legs, abnormal eye movements, swallowing difficulties and slowing of head growth. Fever is common and initially a brain infection is suspected. The exclusion of infection and abnormal brain scan appearances (CT and MRI) usually lead to the diagnosis.

The disease course usually stabilises but neurological problems such as stiffness, feeding difficulties, speech problems, poor vision and learning difficulties persist. Around a third of patients develop chilblain like skin lesions.

Atypical and later onset forms of the condition can occur and the clinical course may be milder.
Those with the most severe form usually do not live past 10 years of age, those with a milder form have been known to survive into adulthood.

Note: Aicardi-Goutieres Syndrome differs from Aicardi Syndrome which is not a leukodystrophy

Aicardi-Goutieres Syndrome is diagnosed using a specialised blood test and through tests on the brain. This typically includes brain scans to detect any irregularities.

Genetic testing is required to confirm the diagnosis.

Treatments for Aicardi-Goutieres Syndrome are still being developed, and there is currently no cure. Treatment typically focuses on managing the symptoms of the disorder. This may include support with feeding and mobility. Occupational, physical, and speech therapists, as well as a dietitian, will support you.

Symptoms such as fevers and an enlarged liver will be treated appropriately, and you may be given medication. If you suffer from seizures, your medical team may also give you medication to manage them. Your medical team may develop an emergency treatment plan for you to follow if the symptoms get worse, which may include going to hospital. It is important that you follow this plan to ensure that the appropriate care is given.

The prognosis depends on the severity of your condition. Those with the most severe form usually do not live past 10 years of age. However, those with a milder form have been known to survive into adulthood.

Aicardi-Goutieres Syndrome is an autosomal recessive disorder, which means that it is inherited from both parents, who are carriers of the disorder through their genes.

All genes come in pairs. Carriers of Aicardi-Goutieres Syndrome have one working gene and one faulty gene. Children inherit one gene from each parent to make their pair. Whether they have Aicardi-Goutieres Syndrome depends on the genes they inherit:

• There is a 50% chance that the child will inherit one faulty and one working gene, which means they will also be a carrier.
• There is a 25% chance that the child will inherit two working genes and not inherit or carry the faulty gene.
• There is a 25% chance that the child will inherit two faulty genes, which means they will have Aicardi-Goutieres Syndrome.

In rare cases, Aicardi-Goutieres Syndrome is inherited in an autosomal dominant inheritance pattern. This means that only one parent has to be affected to pass on the disorder through their genes.

In these cases, children inherit one gene from each parent to make their pair. If one parent has Aicardi-Goutieres Syndrome, there is a 50% chance that the child will also have the disorder

If you think somebody in your family may have Aicardi-Goutieres Syndrome, or that you may be a carrier, contact your medical team who may refer you for genetic testing.

References are available on request. Please contact us by phoning 0845 241 2173 or emailing contact@metabolicsupportuk.org [Resource Library No: APPN01].