15q13.3 Deletion Syndrome
15q13.3 deletion syndrome is also called 15q13.3 microdeletion. For this webpage, we will be using the name 15q13.3 deletion syndrome to encompass the wide range of variants observed in the people identified.
What is 15q13.3 deletion syndrome?
15q13.3 deletion syndrome happens when a person is missing a piece of chromosome 15, one of the body’s 46 chromosomes. Chromosomes are structures in our cells that house our genes. The missing piece can affect learning and how the body develops.
Key Role
The 15q13.3 region on chromosome 15 includes seven genes. Researchers are still trying to learn more about what the genes in this region do. One study suggests that one of the genes called OTUD7A is important for brain function.
Symptoms
Because the 15q13.3 region is important for brain activity, many people who have 15q13.3 deletion syndrome have:
- Developmental delay, or intellectual disability, or both
- Autism spectrum disorder or features of autism
- Other behavioral issues, including attention-deficit/hyperactivity disorder (ADHD), aggression, and rage
- Seizures or an abnormal electroencephalogram, also called EEG (a test that measures the brain’s electrical activity)
- Speech and language delay
- Schizophrenia
- Mood disorders
- Lower than average muscle tone
What causes 15q13.3 deletion syndrome?
15q13.3 deletion 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 15q13.3 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 15q13.3 plays a key role in development, de novo variants in this gene can have a meaningful effect.
Research shows that 15q13.3 deletion syndrome is often the result of a de novo variant in 15q13.3. Many parents who have had their genes tested do not have the 15q13.3 genetic variant found in their child who has the syndrome. In some cases, 15q13.3 deletion syndrome happens because the genetic variant was passed down from a parent.
Autosomal dominant conditions
15q13.3 deletion syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in 16p11.2 they will likely have symptoms of 15q13.3 deletion 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
Why do I or my child have 15q13.3 deletion syndrome?
No parent causes their child’s 15q13.3 deletion syndrome. We know this because no parent has any control over the chromosome 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 genetic change takes place on its own and cannot be predicted or stopped.
What are the chances that other family members or future children will have 15q13.3 deletion syndrome?
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 15q13.3 deletion 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 15q13.3 deletion syndrome, the sibling’s risk of having a child who has 15q13.3 deletion syndrome depends on the sibling’s genes and their parents’ genes.
- If neither parent has the same genetic variant causing 15q13.3 deletion syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit 15q13.3 deletion syndrome.
- If one biological parent has the same genetic variant causing 15q13.3 deletion 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 15q13.3 deletion syndrome, the risk of having a child who has the syndrome is about 50 percent.
How many people have 15q13.3 deletion syndrome?
As of 2024, more than 200 people with 15q13.3 deletion syndrome have been identified in a medical clinic. The first case of 15q13.3 deletion syndrome was described in 2008.
Do people who have 15q13.3 deletion syndrome look different?
People who have 15q13.3 deletion syndrome may look different, but features are non-specific.
How is 15q13.3 deletion syndrome treated?
Scientists and doctors have only just begun to study 15q13.3 deletion 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 15q13.3 deletion 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: epilepsy.com/…t-is-epilepsy/seizure-types
This section includes a summary of information from major published articles. It highlights how many people have different symptoms. To learn more about the articles, see the Sources and References section of this guide.
Behavior and development concerns linked to 15q13.3 deletion syndrome
Depending on the specific 15q13.3 deletion, the 15q13.3 region may have up to seven genes deleted.
Speech and Learning
Just over one-half of people with 15q13.3 deletion syndrome had developmental delay or intellectual disability. Many people had speech delay.
- 74 out of 125 people had developmental delay or intellectual disability (59 percent)
Behavior
Some people with 15q13.3 deletion syndrome had behavioral disorders, including autism, attention-deficit/hyperactivity disorder (ADHD), poor attention span, mood disorder, and aggressive and/or impulsive behavior. Researchers think that about 1 in 10 people with 15q13.3 deletion syndrome might develop schizophrenia or mood disorders.
- 44 out of 125 people had a behavioral disorder (35 percent)
- 12 out of 125 people had autism (10 percent)
- 9 out of 125 people had ADHD (7 percent)
- 14 out of 125 people had schizophrenia (11 percent)
- 12 out of 125 people had a mood disorder (10 percent)
Brain
About 1 in 3 people with 15q13.3 deletion syndrome had seizures, most commonly absence seizures in childhood. Other seizure types included myoclonic absence, atonic seizures, and focal with impaired awareness. One small study suggested that the anti-seizure medication valproate was effective. Some people had brain changes observed on magnetic resonance imaging (MRI), such as brain cysts, hypoplasia, and dilation of certain brain regions.
- 37 out of 125 people had seizures (30 percent)
Medical and physical concerns linked to 15q13.3 deletion syndrome
Other medical findings
Developmental issues varied widely from person to person with 15q13.3 deletion syndrome. Other medical issues included heart defects; vision issues; gastrointestinal issues; hypothyroidism or insulin-resistant diabetes; renal cyst (a narrowing of the tube that carries urine out of the body), and kidney stones.
Where can I find support and resources?
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.”
- Learn more about Simons Searchlight: www.simonssearchlight.org/frequently-asked-questions
- Simons Searchlight webpage with more information on 15q13.3 deletion: www.simonssearchlight.org/research/what-we-study/15q13-3-deletion
- Simons Searchlight Facebook group: https://www.facebook.com/groups/15q13-3-deletion
Sources and References
The content in this guide comes from published studies about 15q13.3 deletion syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.
- van Bon, B. W. M., Mefford, H. C., de Vries, B. B. A., & Schaaf, C. P. 15q13.3 recurrent deletion. 2022 Nov 17. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2004. Available from: https://www.ncbi.nlm.nih.gov/books/NBK50780/
- Whitney, R., Nair, A., McCready, E., Keller, A. E., Adil, I. S., Aziz, A. S., Borys, O., Siu, K., Shah, C., … & RamachandranNair, R. (2021). The spectrum of epilepsy in children with 15q13.3 microdeletion syndrome. Seizure, 92, 221-229. https://pubmed.ncbi.nlm.nih.gov/34601452/