Will Our Next Child Have Aicardi-Goutières Syndrome?

Thinking about expanding your family after your child receives an Aicardi-Goutières syndrome (AGS) diagnosis can feel overwhelming and frightening. If you are wondering about the chances of a future child having the condition, the answer depends heavily on the specific gene involved and how it was passed down. In most cases, AGS is inherited in an autosomal recessive pattern, which means there is a 25% chance that a future child will have the syndrome ^[1][2][3].

Autosomal Recessive Inheritance (Most Common)

For most families, AGS is an autosomal recessive condition ^[1][2][3]. This means that a child must inherit two copies of the mutated gene—one from each parent—to develop the syndrome ^[4].

In this scenario, both parents are carriers. Carriers typically do not have any symptoms of AGS because they still have one working copy of the gene, which is enough to keep the body functioning normally.

If both parents are carriers, for every pregnancy, the statistical chances are:

• A 25% chance the child will inherit both mutated genes and have AGS.
• A 50% chance the child will inherit one mutated gene and one normal gene, making them a carrier just like the parents.
• A 25% chance the child will inherit two normal genes, meaning they will not have AGS and will not be a carrier.

Autosomal Dominant Inheritance (Rare)

While less common, some forms of AGS are caused by autosomal dominant mutations in specific genes, such as IFIH1, TREX1, or ADAR ^[5][6][7]. You can find out which specific gene is involved by looking at your child’s genetic testing report or by asking their neurologist or geneticist. In an autosomal dominant condition, a child only needs to inherit one copy of the mutated gene to develop the syndrome.

• Inherited from a parent: If one parent has the dominant mutation, there is a 50% chance of passing it to a child for each pregnancy.
• De novo (spontaneous) mutations: Frequently, these dominant mutations are de novo, meaning they occurred spontaneously in the child for the first time and were not inherited from either parent ^[8]. If a genetic test confirms that the mutation is de novo and neither parent carries it in their blood, the risk of having another child with AGS is generally very low. However, the risk is not completely zero (usually around 1-2%) due to a rare phenomenon called germline mosaicism, where the mutation is only present in a parent’s egg or sperm cells.

The Role of Genetic Counseling

Because AGS is genetically complex, genetic counseling is a critical step for family planning ^[9][10]. A genetic counselor can review your child’s genetic testing report and determine your exact recurrence risk ^[10]. During a counseling appointment, the counselor will typically review your family history, explain your child’s specific test results, and may discuss drawing blood from you and your partner for your own carrier testing.

It is important to know that even when siblings inherit the exact same AGS-causing genetics, the specific symptoms and their severity can vary significantly between them ^[11]. This uncertainty—knowing that predicting a future child’s symptoms based on an older sibling’s experience is very difficult—is often one of the hardest aspects of AGS to navigate ^[11]. Your medical team is there to support you through these unknowns. Families exploring family planning can also work with their team to discuss options like prenatal testing or preimplantation genetic testing (testing embryos during IVF for the specific mutation) ^[12].