17q12 Deletion Syndrome
17q12 deletion syndrome is also called 17q12 microdeletion syndrome. For this webpage, we will be using the name 17q12 deletion syndrome to encompass the wide range of variants observed in the people identified.
What is 17q12 deletion syndrome?
17q12 deletion syndrome happens when a person is missing a piece of chromosome 17, 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
Genes within the 17q12 region are important for brain development and function.
Symptoms
Because the 17q12 region is important in brain activity, many people who have 17q12 deletion syndrome have:
- Developmental delay
- Intellectual disability
- Autism
- Bipolar disorder
- Seizures
- Heart defects
- Genital defects, in both females and males
- Structural or functional issues of the kidney and urinary tract
- Maturity-onset diabetes of the young type 5 (MODY 5)
- Brain changes seen on magnetic resonance imaging (MRI)
What causes 17q12 deletion syndrome?
17q12 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 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 deletion 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 deletion syndrome happens because the genetic variant was passed down from a parent.
Autosomal dominant conditions
17q12 deletion 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 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
What does my child have 17q12 deletion syndrome?
No parent causes their child’s 17q12 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 17q12 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 17q12 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 17q12 deletion syndrome, the sibling’s risk of having a child who has 17q12 deletion syndrome depends on the sibling’s genes and their parents’ genes.
- If neither parent has the same genetic variant causing 17q12 deletion syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit 17q12 deletion syndrome.
- If one biological parent has the same genetic variant causing 17q12 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 17q12 deletion syndrome, the risk of having a child who has the syndrome is about 50 percent.
Do all people who have 17q12 deletion syndrome have symptoms?
Not necessarily. Some people do not have any symptoms. Some people may not learn that they have this genetic change until it is found in their children.
Will all of the people in a family that have 17q12 deletion syndrome have the same symptoms?
Not necessarily. Family members who have the same chromosome change can have different symptoms.
How many people have 17q12 deletion syndrome?
As of 2024, at least 295 people with 17q12 deletion syndrome have been identified in medical research.
Do people who have 17q12 deletion syndrome look different?
People who have 17q12 deletion syndrome may look different. Appearance can vary and can include some but not all of these features:
- High, flat forehead
- Low nasal bridge
- Deep-set eyes
- Full cheeks
- High-arched eyebrows
- Small and underdeveloped nails
- Webbing between the second and third fingers, or the second and third toes, or both
- Curved fifth finger
- Larger than average head size
How is 17q12 deletion syndrome treated?
At this point, there are no medicines designed to treat 17q12 deletion 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 deletion 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 deletion syndrome
The 17q12 deletion region differs from person to person and might have up to about 15 genes removed. Some people inherit the 17q12 deletion from a parent who may or may not have medical features.
Some researchers think that an important gene within the 17q12 region is the HNF1B gene. However, other genes in the region may also be important for brain development and function.
Speech and Learning
About one-half of people with 17q12 deletion syndrome had developmental delay or intellectual disability. Most often, learning difficulties were mild. Language delays were common.
- 37 out of 79 people had a developmental delay or intellectual disability (47 percent)
- 14 out of 110 people required placement in a special needs school (13 percent)
Behavior
Some people with 17q12 deletion syndrome had autism, schizophrenia, or bipolar disorder. Researchers think that people with 17q12 deletion syndrome might have a higher rate of schizophrenia or bipolar disorder than people in the general population.
- 9 percent of people had features of autism
Brain
Some people with 17q12 deletion syndrome had seizures. Some people had abnormal brain changes seen on magnetic resonance imaging (MRI). Some findings included ventricular dilation, mild cerebellar atrophy, abnormal signal intensity of the white matter, or atrophy of the hippocampus.
- 7 out of 50 people had seizures (14 percent)
- 8 out of 31 people had abnormal MRI findings (26 percent)
Medical and physical concerns linked to 17q12 deletion syndrome
Kidney issues
Kidney formation and functional issues were the most commonly reported feature of 17q12 deletion syndrome. Cystic dysplastic kidneys, in which there are various cysts in the kidneys that alter their structure, is the most common structural issue. Other types of kidney development issues that have been described include single kidney, horseshoe kidney, and urine collection issues.
- 130 out of 148 people had cystic dysplastic kidneys and other structural kidney issues (88 percent)
Diabetes
Maturity-onset diabetes of the young type 5 (MODY 5) is a form of diabetes caused by a genetic variation or deletion in the HNF1B gene. It is sometimes mistaken for type II diabetes. Most people receive a MODY 5 diagnosis before the age of 25.
About one-half of people with 17q12 deletion syndrome ended up developing MODY 5, and most eventually required insulin therapy over their lifetime.
Liver issues
About one-half of people had elevated liver enzymes. Some people with elevated liver enzymes had no other symptoms, and some had cholestasis, a slowing of the bile produced by the liver.
- 64 out of 133 people had elevated liver enzymes (48 percent)
Pancreatic issues
Some people with 17q12 deletion syndrome had abnormal findings on imaging of the pancreas.
- 32 out of 105 people had a structural defect of the pancreas (31 percent)
Other medical findings
Less commonly, people had heart defects, were shorter than average, or had bone formation issues. Some of the bone formation issues included joints that were too relaxed or long, thin hands and feet.
- 9 out of 45 people had heart defects (20 percent)
- 9 out of 39 people were shorter than average (23 percent)
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 deletion syndrome: www.simonssearchlight.org/research/what-we-study/17q12-deletion
- Simons Searchlight 17q12 deletion syndrome Facebook Community: www.facebook.com/groups/235285544024090
Sources and References
The content in this guide comes from published studies about 17q12 deletion syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.
- Laffargue F. et al. Archives of Disease in Childhood, 100, 259-264, (2015). Towards a new point of view on the phenotype of patients with a 17q12 microdeletion syndrome www.ncbi.nlm.nih.gov/pubmed/20154674
- Rasmussen M. et al. American Journal of Medical Genetics Part A, 170, 2934-2942, (2016). 17q12 deletion and duplication syndrome in Denmark-A clinical cohort of 38 patients and review of the literature www.ncbi.nlm.nih.gov/pubmed/27409573
- Mitchel MW. et al. Gene Reviews, (2016). 17q12 recurrent deletion syndrome www.ncbi.nlm.nih.gov/books/NBK401562
- Ge, S., Yang, M., Cui, Y., Wu, J., Xu, L., Dong, J., & Liao, L. (2022). The clinical characteristics and gene mutations of maturity-onset diabetes of the young type 5 in sixty-one patients. Frontiers in Endocrinology (Lausanne), 13, 911526. https://pubmed.ncbi.nlm.nih.gov/35846334/
- Isa, H. M., Salman, L. I., Jr., Almaa, Z. A., Jr., Busehail, M. Y., & Alherz, Z. A. (2022). 17q12 microdeletion syndrome as a rare cause of elevated liver enzymes: Case report and literature review. Cureus, 14(12), e32233. https://pubmed.ncbi.nlm.nih.gov/36620780/
- Lee, R., Choi, J. E., Mun, E., Kim, K. H., Choi, S. A., & Kim, H. S. (2024). A case of chromosome 17q12 deletion syndrome with type 2 Mayer-Rokitansky-Küster-Hauser syndrome and maturity-onset diabetes of the young type 5. Children (Basel), 11(4), 404. https://pubmed.ncbi.nlm.nih.gov/38671621/