Can Autosomal Dominant Optic Atrophy Skip a Generation?

Autosomal Dominant Optic Atrophy (ADOA) does not truly “skip” a generation genetically, but it can certainly look like it does. Because of how the disease affects different people, a parent might pass the mutated gene to their child, but that child could have symptoms so mild that they never realize they have the condition ^[1][2]. When that child grows up and has a baby who develops obvious vision loss, it appears as though the disease skipped a generation.

The 50% Chance: Autosomal Dominant Inheritance

ADOA is an inherited genetic condition. Most cases of classic ADOA are caused by a mutation in a gene called OPA1 ^[3]. Everyone has two copies of the OPA1 gene, but in ADOA, one copy is mutated. The term autosomal dominant describes how this mutated gene is passed from parent to child:

• Autosomal means the gene is not tied to sex chromosomes, so men and women are equally likely to inherit and pass on the condition.
• Dominant means that a child only needs to inherit one copy of the mutated gene from one parent to have the condition ^[4].

Because you have ADOA, there is a 50% chance with each pregnancy that you will pass the mutated gene to your child, and a 50% chance that you will pass on the healthy gene ^[5]. If your child inherits your healthy gene, they will not have ADOA and cannot pass it on to their future children.

Why It Looks Like It Skips: Variable Expressivity and Incomplete Penetrance

If a child does inherit the mutated OPA1 gene, it is very difficult to predict how severely their vision will be affected. Importantly, your symptom severity does not predict your child’s severity—if you have mild vision loss, your child could still experience severe vision loss, or vice versa ^[6]. Genetic counselors use two key concepts to explain this:

Variable Expressivity

Variable expressivity means that people with the exact same genetic mutation can experience vastly different symptoms ^[6]. Within the same family, one person might experience severe vision loss starting in early childhood, while another might only have very mild vision issues that are barely noticeable ^[2]. In some cases, factors like birth weight, gestational age, and lifestyle habits that stress the mitochondria—such as smoking and excessive alcohol use—may influence how severely the disease expresses itself ^[7][8].

Incomplete Penetrance

Incomplete penetrance refers to the fact that some people who carry the genetic mutation for ADOA never develop any symptoms of the disease at all during their lifetime ^[1][9]. They are completely asymptomatic.

Because of variable expressivity and incomplete penetrance, the mutated gene can quietly pass through a generation ^[6][10]. If your child inherits the gene but has no symptoms, they might go their whole life thinking they don’t have ADOA. However, they would still have a 50% chance of passing the gene to their own children, who might then experience much more severe vision loss ^[5].

Looking Forward: Family Planning and Child Monitoring

If you are planning to have children, it can be stressful thinking about the 50% inheritance risk. It is highly recommended to speak with a genetic counselor. They can discuss proactive family planning options, such as in vitro fertilization (IVF) combined with preimplantation genetic testing (PGT-M), which allows doctors to screen embryos for the OPA1 mutation before pregnancy.

If you already have children, genetic testing can confirm if they have inherited the OPA1 mutation, even if they have no obvious vision problems ^[11]. If they carry the mutation, or if you choose not to test them genetically, they should have routine eye exams with an ophthalmologist or neuro-ophthalmologist. Standard eye exams may miss the subtle signs of ADOA, so specialized imaging of the optic nerve is necessary to track any early changes in their vision over time.