17q12 Duplication Syndrome
17q12 duplication syndrome is also called 17q12 microduplication. For this webpage, we will be using the name 17q12 duplication syndrome to encompass the wide range of variants observed in the people identified.
What is 17q12 duplication syndrome?
17q12 duplication syndrome happens when a person has an extra piece of chromosome 17, one of the body’s 46 chromosomes. Chromosomes are structures in our cells that house our genes. The extra piece can affect learning and how the body develops.
Key Role
Genes within the 17q12 region are important for brain development and function.
Symptoms
Because genes in the 17q12 region are important in brain development and function, many people who have 17q12 duplication syndrome have:
- Developmental delay
- Intellectual disability
- Seizures
- Brain changes seen on magnetic resonance imaging (MRI)
- Autism
- Schizophrenia
- Speech delays
- Aggression
- Self-injury behavior
- Low muscle tone
- Gross motor delay
- Hormone issues
- Heart and kidneys issues
What causes 17q12 duplication syndrome?
17q12 duplication 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 17q12 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 17q12 plays a key role in development, de novo variants in this gene can have a meaningful effect.
Research shows that 17q12 duplication syndrome is often the result of a de novo variant in 17q12. Many parents who have had their genes tested do not have the 17q12 genetic variant found in their child who has the syndrome. In some cases, 17q12 duplication syndrome happens because the genetic variant was passed down from a parent.
Autosomal dominant conditions
17q12 duplication syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in 17q12 they will likely have symptoms of 17q12 duplication 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
What does my child have 17q12 duplication syndrome?
No parent causes their child’s 17q12 duplication 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 17q12 duplication 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 17q12 duplication 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 17q12 duplication syndrome, the sibling’s risk of having a child who has 17q12 duplication syndrome depends on the sibling’s genes and their parents’ genes.
- If neither parent has the same genetic variant causing 17q12 duplication syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit 17q12 duplication syndrome.
- If one biological parent has the same genetic variant causing 17q12 duplication 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 17q12 duplication syndrome, the risk of having a child who has the syndrome is about 50 percent.
How many people have 17q12 duplication syndrome?
As of 2025, over 90 people with 17q12 duplication syndrome have been described in medical research. But, most people who carry a 17q12 duplication do not have any symptoms, making it difficult to know how common this condition is.
Do people who have 17q12 duplication syndrome look different?
People with 17q12 duplication syndrome may look different. Appearance can vary and can include some but not all of these features:
- Smaller than average head size
- Eye defects
How is 17q12 duplication syndrome treated?
At this point, there are no medicines designed to treat 17q12 duplication 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
- Developmental 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 17q12 duplication syndrome should begin as early as possible, ideally before a child begins school.
Your doctor can recommend whether to see an endocrinologist to check for kidney and urinary issues.
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/learn/types-seizures.
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 17q12 duplication syndrome
Speech and learning
People with 17q12 duplication syndrome had developmental delay or intellectual disability and speech and/or language impairment. But, many people have normal intellectual ability.
- 49 percent of people had developmental delay
- 71 percent of people had intellectual disability
- 65 percent of people had speech and/or language impairment
Behavior
People with 17q12 duplication syndrome had behavioral issues, such as autism, aggression, self-injury behaviors, and compulsive disorders. Researchers think that people with 17q12 duplication syndrome might have a higher rate of schizophrenia than people in the general population.
- 62 percent of people had behavioral issues
Brain
Some people with 17q12 duplication syndrome had neurological medical issues, including a smaller than average head size (microcephaly), seizures, brain changes seen on magnetic resonance imaging (MRI), and lower than average muscle tone (hypotonia).
- 40 percent of people had microcephaly
- 36 percent of people had seizures
- 73 percent of people had hypotonia
Medical and physical concerns linked to 17q12 duplication syndrome
Vision
People with 17q12 duplication syndrome had vision issues, such as crossed eyes (strabismus), an imperfection of the eye that causes blurred distance and near vision (astigmatism), cataracts, or an area of missing tissue in the eye (coloboma).
- 28 percent of people had vision issues
Growth
Some people with 17q12 duplication syndrome might be shorter than average or taller than average. About 1 in 5 people had kidney defects, such as horseshoe kidney, kidney cysts, and hypoplastic kidneys. Some people had heart defects at birth.
- 22 percent of people were shorter than average
- 6 percent of people were taller than average
- 20 percent of people had kidney defects
- 14 percent of people had a heart defect at birth
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Endocrine
People with 17q12 duplication syndrome had endocrine issues, including diabetes, growth hormone deficiency, low level of salt in the blood (hyponatremia), or high level of potassium in the blood.
- 26 percent of people had endocrine issues
Where can I find support and resources?
17q12 Foundation
The 17q12 Foundation raises awareness, provides up-to-date information, and facilitates resources to affected individuals and families through supporting research of chromosome 17q12 deletion and duplication syndromes.
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 page on 17q12 duplication syndrome: www.simonssearchlight.org/research/what-we-study/17q12-duplication
- Simons Searchlight 17q12 deletion syndrome Facebook Community: https://www.facebook.com/groups/17q12duplication
Sources and References
- Das, S., Samarasinghe, L., Deva, S., Fernandez Co, E. M., Poudel, S., Dave, T., Prasad, S., & Sarangi, A. (2024). Complex neuropsychiatric presentation of 17q12 duplication syndrome: A case report. SAGE Open Medical Case Reports, 12, 2050313X241233184. doi:10.1177/2050313×241233184
- Mefford, H. 17q12 recurrent duplication. 2022 Jan 13. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK344340/