GENE GUIDE

CIC-Related Syndrome

This guide is not meant to take the place of medical advice. Please consult with your doctor about your genetic results and health care choices. This Gene Guide was last updated on 2024. As new information comes to light with new research we will update this page. You may find it helpful to share this guide with friends and family members or doctors and teachers of the person who has CIC-Related Syndrome.
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CIC-related syndrome happens when there are changes to the CIC gene. These changes can keep the gene from working as it should.

Key Role

The CIC gene helps control other genes in the cell.

Symptoms

Because the CIC gene is important in the development and function of brain cells, many people who have CIC-related syndrome have:

  • Intellectual disability and developmental disability
  • Autism
  • Developmental delay
  • Developmental regression
  • Poor speech
  • Seizures
  • Brain changes seen on magnetic resonance imaging (MRI)

CIC-related syndrome is a genetic condition, which means that it is caused by variants in genes. Our genes contain the instructions, or code, that tell our cells how to grow, develop, and work. Every child gets two copies of the CIC gene: one copy from their mother’s egg, and one copy from their father’s sperm. In most cases, parents pass on exact copies of the gene to their child. But the process of creating the egg or sperm is not perfect. A change in the genetic code can lead to physical issues, developmental issues, or both. 

Sometimes a spontaneous variant happens in the sperm, egg or after fertilization. When a brand new genetic variant happens in the genetic code is called a ‘de novo’ genetic variant. The child is usually the first in the family to have the genetic variant.

De novo variants can take place in any gene. We all have some de novo variants, most of which don’t affect our health. But because CIC plays a key role in development, de novo variants in this gene can have a meaningful effect. 

Research shows that CIC-related syndrome is often the result of a de novo variant in CIC. Many parents who have had their genes tested do not have the CIC genetic variant found in their child who has the syndrome. In some cases, CIC-related syndrome happens because the genetic variant was passed down from a parent.

Autosomal dominant conditions

CIC-related syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in CIC they will likely have symptoms of CIC-related syndrome. For someone with an autosomal dominant genetic syndrome, every time they have a child there is a 50 percent chance they pass on the same genetic variant and a 50 percent chance they do not pass on the same genetic variant.

Autosomal Dominant Genetic Syndrome

GENE / gene
GENE / gene
Genetic variant that happens in sperm or egg, or after fertilization
GENE / gene
Child with de novo genetic variant
gene / gene
Non-carrier child
gene / gene
Non-carrier child

Why does my child have a change in the CIC gene?

No parent causes their child’s CIC-related syndrome. We know this because no parent has any control over the gene changes that they do or do not pass on to their children. Please keep in mind that nothing a parent does before or during the pregnancy causes this to happen. The gene change takes place on its own and cannot be predicted or stopped.

Each family is different. A geneticist or genetic counselor can give you advice on the chance that this will happen again in your family.

The risk of having another child who has CIC-related syndrome depends on the genes of both biological parents. 

  • If neither biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is on average 1 percent. This 1 percent chance is higher than the chance of the general population. The increase in risk is due to the very unlikely chance that more of the mother’s egg cells or the father’s sperm cells carry the same genetic variant. 
  • If one biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is 50 percent. 

For a symptom-free brother or sister of someone who has CIC-related syndrome, the sibling’s risk of having a child who has CIC-related syndrome depends on the sibling’s genes and their parents’ genes. 

  • If neither parent has the same genetic variant causing CIC-related syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit CIC-related syndrome. 
  • If one biological parent has the same genetic variant causing CIC-related syndrome, the symptom-free sibling has a 50 percent chance of also having the same genetic variant. If the symptom-free sibling has the same genetic variant, their chance of having a child who has the genetic variant is 50 percent. 

For a person who has CIC-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2024, at least 49 people with CIC-related syndrome have been identified in the medical literature. The first case of CIC-related syndrome was described in 2010.

People with CIC-related syndrome may look different. Appearance can vary and can include, but is not limited to, lower than average muscle tone.

Scientists and doctors have only just begun to study CIC-related syndrome. At this point, there are no medicines designed to treat the syndrome. A genetic diagnosis can help people decide on the best way to track the condition and manage therapies. Doctors can refer people to specialists for:

  • Physical exams and brain studies.
  • Genetics consults.
  • Development and behavior studies.
  • Other issues, as needed.

A developmental pediatrician, neurologist, or psychologist can follow progress over time and can help:

  • Suggest the right therapies. This can include physical, occupational, speech, or behavioral therapy.
  • Guide individualized education plans (IEPs).

Specialists advise that therapies for CIC-related syndrome should begin as early as possible, ideally before a child begins school.

If seizures happen, consult a neurologist. There are many types of seizures, and not all types are easy to spot. To learn more, you can refer to resources such as the Epilepsy Foundation’s website: www.epilepsy.com/learn/types-seizures.

This section includes a summary of information from major published articles describing people who have variants in the CIC gene. It highlights how many people have different symptoms. To learn more about the articles, see the Sources and references section of this guide.

To date, only 14 people with CIC-related syndrome have been described in medical research. Current research suggests that this condition is caused by a loss of some of the CIC protein in cells, also known as a haploinsufficiency. Another way to describe this is that there is not enough of the CIC protein in cells.

Because this summary includes a small number of people, the frequency of some of the medical features might change when we learn from more families.

Brain

Everyone with CIC-related syndrome had developmental delay or intellectual disability. Some people had brain changes on magnetic resonance imaging (MRI). About one-half of people had a history of seizures.

  • 9 out of 9 people had developmental delay or intellectual disability (100 percent)
  • 3 out of 8 people had brain changes on MRI imaging (38 percent)
  • 4 out of 9 people had a history of seizures (44 percent)
100%
9 out of 9 people had developmental delay or intellectual disability.
38%
3 out of 8 people had brain changes on MRI imaging.
44%
4 out of 9 people had a history of seizures.

Learning

Many people had autism or attention deficit hyperactivity disorder (ADHD).

  • 5 out of 9 people had autism (56 percent)
  • 4 out of 9 people had attention deficit hyperactivity disorder (44 percent)
56%
5 out of 9 people had autism.
44%
4 out of 9 people had attention deficit hyperactivity disorder.

Other

More research is needed to understand if CIC variants are associated with cancer. There was 1 out of 4 people who had lymphoblastic leukemia.

Where can I find support and resources?

CIC Gene Families

The hope for this group is that it may provide support, education and encouragement to CIC families. This is a private group, information shared here should not be shared elsewhere, unless you have gained permission from the family involved.

Simons Searchlight

Simons Searchlight is an online international research program, building an ever growing natural history database, biorepository, and resource network of over 175 rare genetic neurodevelopmental disorders. By joining their community and sharing your experiences, you contribute to a growing database used by scientists worldwide to advance the understanding of your genetic condition. Through online surveys and optional blood sample collection, they gather valuable information to improve lives and drive scientific progress. Families like yours are the key to making meaningful progress. To register for Simons Searchlight, go to the Simons Searchlight website at www.simonssearchlight.org and click “Join Us.”

Sources and References

The content in this guide comes from published studies about CIC-related syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.

  • Vissers LE. et al. Nature Genetics, 42, 1109-1112, (2010). A de novo paradigm for mental retardation www.pubmed.ncbi.nlm.nih.gov/21076407
  • Lu HC. et al. Nature Genetics, 49, 527-536, (2017). Disruption of the ATXN1-CIC complex causes a spectrum of neurobehavioral phenotypes in mice and humans www.ncbi.nlm.nih.gov/pmc/articles/PMC5374026
  • Sharma, S., Hourigan, B., Patel, Z., Rosenfeld, J. A., Chan, K. M., Wangler, M. F., Yi, J. S., Lehman, A., Horvath, G., Cloos, P. A., & Tan, Q. (2022). Novel CIC variants identified in individuals with neurodevelopmental phenotypes. Human Mutation, 43(7), 889-899. https://pubmed.ncbi.nlm.nih.gov/35165976/

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