6q16 Deletion Syndrome
6q16 deletion syndrome is also called 6q16 microdeletion syndrome. For this webpage, we will be using the name 6q16 deletion syndrome to encompass the wide range of variants observed in the people identified.
What is 6q16 deletion syndrome?
6q16 deletion syndrome happens when a person is missing a piece of chromosome 6, 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 6q16 region plays a role in brain development.
Symptoms
Because the 6q16 region is important for brain activity, many people who have 6q16 deletion syndrome have:
- Developmental delay
- Learning difficulties
- Behavioral issues, including hyperactivity and features of autism
- Excessive hunger and obesity that begins early in life
- Low muscle tone
- Changes in appearance
- Heart conditions
- Kidney disorders
- Eye issues
What causes 6q16 deletion syndrome?
6q16 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 16p11.2 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 6q16 plays a key role in development, de novo variants in this gene can have a meaningful effect.
Research shows that 6q16 deletion syndrome is often the result of a de novo variant in 6q16. Many parents who have had their genes tested do not have the 6q16 genetic variant found in their child who has the syndrome. In some cases, 6q16 deletion syndrome happens because the genetic variant was passed down from a parent.
Autosomal dominant conditions
6q16 deletion syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in 6q16 they will likely have symptoms of 6q16 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 does my child have a change in the 6q16 gene?
No parent causes their child’s 6q16 deletion 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.
Do all people with 6q16 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.
What are the chances that other family members of future children will have 6q16 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 16p11.2 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 6q16 deletion syndrome, the sibling’s risk of having a child who has 6q16 deletion syndrome depends on the sibling’s genes and their parents’ genes.
- If neither parent has the same genetic variant causing 6q16 deletion syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit 16p11.2 deletion syndrome.
- If one biological parent has the same genetic variant causing 6q16 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 6q16 deletion syndrome, the risk of having a child who has the syndrome is about 50 percent.
How many people have 6q16 deletion syndrome?
As of 2024, over 40 people with 6q16 deletion syndrome have been identified in medical research. The important genes that cause 6q16 deletion syndrome have not been confirmed, and some of the medical literature has estimated the number of people with 6q16 deletion, if you include all the various deletion sizes, to be over 200 people. There are likely many more undiagnosed people who have the syndrome. Scientists expect to find more people who have the syndrome as access to genetic testing improves.
Do people who have 6q16 deletion syndrome look different?
People who have 6q16 deletion syndrome may look different. Appearance can vary and can include some but not all of these features:
- Round face and full cheeks
- Large head, also known as macrocephaly
- Wide head with a flat back, also called brachycephaly
- A forehead that sticks out
- Large space between the nose and the upper lip
- Fat, round, or bulging nose
How is 6q16 deletion syndrome treated?
Scientists and doctors have only just begun to study 6q16 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 6q16 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 6q16 deletion syndrome
Depending on the specific 6q16 deletion, the 6q16 region may have 9 genes deleted, but it could be more or less.
Rarely, people inherit the 6q16 deletion from a parent. For most people with 6q16 deletion syndrome, the condition is brand new, also called de novo.
Speech and Learning
All people with 6q16 deletion syndrome had developmental delay or intellectual disability, and language delays or impairment.
- 42 out of 42 people had developmental delay or intellectual disability (100 percent)
- 12 out of 12 people had language delays or impairment (100 percent)
Behavior
More than one-half of people who have the syndrome had behavioral issues, including features of autism or attention-deficit/hyperactivity disorder (ADHD). This ranged from repetitive movements and hyperactivity to tantrums and aggressive behavior. Some people had sleep problems.
Brain
More than one-half of people with 6q16 deletion syndrome had seizures and brain changes observed on magnetic resonance imaging (MRI) or other imaging.
- 4 out of 6 people had seizures (67 percent)
- 14 out of 20 people had brain changes seen on MRI (70 percent)
Medical and physical concerns linked to 6q16 deletion syndrome
Weight issues
People with 6q16 deletion syndrome were at risk of developing obesity and had eating behavior disorders, such as a feeling of extreme, insatiable hunger (hyperphagia).
- 29 out of 35 people were overweight or obese (83 percent)
- 10 out of 12 people had eating behavior disorders (83 percent)
Eyes and vision
Eye issues were common, including nearsightedness or crossed eyes, also called strabismus.
Where can I find support and resources?
Unique – 6q16 Deletion Guidebook
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 6q16 deletion: www.simonssearchlight.org/research/what-we-study/6q16-deletion
- Simons Searchlight Facebook group: 6q16 Deletion Facebook group
Sources and References
- Cutillo, G., Bonacchi, R., Cecchetti, G., Bellini, A., Vabanesi, M., Zambon, A., Natali Sora, M. G., Baldoli, C., Del Carro, U., … & Filippi, M. (2023). Interstitial 6q deletion in a patient presenting with drug-resistant epilepsy and Prader-Willi like phenotype: An electroclinical description with literature review. Seizure, 109, 45-49. https://pubmed.ncbi.nlm.nih.gov/37210930/
- D’Angelo, C. S., Varela, M. C., de Castro, C. I. E., Otto, P. A., Perez, A. B. A., Lourenço, C. M., Kim, C. A., Bertola, D. R., Kok, F., … & Koiffmann, C. P. (2018). Chromosomal microarray analysis in the genetic evaluation of 279 patients with syndromic obesity. Molecular Cytogenetics, 11, 14. https://pubmed.ncbi.nlm.nih.gov/29441128/
- Okazaki, T., Kawaguchi, T., Saiki, Y., Aoki, C., Kasagi, N., Adachi, K., Saida, K., Matsumoto, N., Nanba, E., & Maegaki, Y. (2022). Clinical course of a Japanese patient with developmental delay linked to a small 6q16.1 deletion. Human Genome Variation, 9(1), 14. https://pubmed.ncbi.nlm.nih.gov/35581197/
- Schönauer, R., Jin, W., Findeisen, C., Valenzuela, I., Devlin, L. A., Murrell, J., Bedoukian, E. C., Pöschla, L., Hantmann, E., … & Halbritter, J. (2023). Monoallelic intragenic POU3F2 variants lead to neurodevelopmental delay and hyperphagic obesity, confirming the gene’s candidacy in 6q16.1 deletions. American Journal of Human Genetics, 110(6), 998-1007. https://pubmed.ncbi.nlm.nih.gov/37207645/