KDM3B-Related Syndrome
KDM3B-related syndrome is also called Diets-Jongmans syndrome. For this webpage, we will be using the name KDM3B-related syndrome to encompass the wide range of variants observed in the people identified.
What is KDM3B-related syndrome?
KDM3B-related syndrome happens when there are changes to the KDM3B gene. These changes can keep the gene from working as it should.
Key Role
The KDM3B gene plays a role in brain development.
Because the KDM3B gene is important in brain development and function, many people who have KDM3B-related syndrome have:
- Developmental delay
- Intellectual disability
- Autism
- Motor delays
- Speech delays
- Attention deficit hyperactivity disorder, or ADHD
- Lower than average muscle tone
What causes KDM3B-related syndrome?
KDM3B-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 KDM3B 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 KDM3B plays a key role in development, de novo variants in this gene can have a meaningful effect.
Research shows that KDM3B-related syndrome is often the result of a de novo variant in KDM3B. Many parents who have had their genes tested do not have the KDM3B genetic variant found in their child who has the syndrome. In some cases, KDM3B-related syndrome happens because the genetic variant was passed down from a parent.
Autosomal dominant conditions
KDM3B-related syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in KDM3B they will likely have symptoms of KDM3B-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
Why does my child have a change in the KDM3B gene?
No parent causes their child’s KDM3B-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.
What are the chances that other family members of future children will have KDM3B-related 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 KDM3B-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 KDM3B-related syndrome, the sibling’s risk of having a child who has KDM3B-related syndrome depends on the sibling’s genes and their parents’ genes.
- If neither parent has the same genetic variant causing KDM3B-related syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit KDM3B-related syndrome.
How many people have KDM3B-related syndrome?
As of 2024, at least 27 people with KDM3B-related syndrome have been identified in a medical clinic. The first case of KDM3B-related syndrome was described in 2019.
Do people who have KDM3B-related syndrome look different?
People who have KDM3B-related syndrome may look different. Appearance can vary and can include some but not all of these features:
- Smaller than average height
- Eyelids that droop
- Wide mouth
- Broad tip of the nose
- Pointed and prominent chin
How is KDM3B-related syndrome treated?
Scientists and doctors have only just begun to study KDM3B-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 KDM3B-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 published articles. It highlights how many people have different symptoms. To learn more about the article, see the Sources and References section of this guide.
Behavior and development concerns linked to KDM3B-related syndrome
Speech and Learning
Most people with KDM3B-related syndrome had developmental delay or intellectual disability. Some children had speech delays.
- 18 out of 20 people had developmental delay or intellectual disability (90 percent)
Behavior
Many people with KDM3B-related syndrome had behavioral concerns, attention deficit hyperactivity disorder, or ADHD, and autism.
- 8 out of 15 people had behavioral concerns (53 percent)
- 4 out of 16 people had ADHD (25 percent)
- 4 out of 16 people had autism or features of autism (25 percent)
Brain
Some people with KDM3B-related syndrome had seizures.
- 3 out of 15 people had seizures (20 percent)
Medical and physical concerns linked to KDM3B-related syndrome
Feeding and digestion
More than one-half had feeding difficulties as infants. Feeding difficulties may result in lower than average weight.
- 11 out of 17 people had feeding difficulties (65 percent)
Growth
People with KDM3B-related syndrome had shorter than average height.
- 10 out of 19 people were short (53 percent)
Mobility
Some people with KDM3B-related syndrome had low muscle tone and motor or movement difficulties. Some children had motor or movement difficulties.
- 5 out of 13 people had low muscle tone (39 percent)
Other features
Some people with KDM3B-related syndrome had eye defects or hearing loss. Joint hypermobility and hernias, such as umbilical, inguinal, or diaphragmatic hernias, were reported.
Potential cancer risk
Four out of 20 people who had KDM3B-related syndrome had childhood cancers:
- A 13-year-old diagnosed with a type of blood cancer called acute myeloid leukemia
- A 17-year-old diagnosed with an immune system cancer called Hodgkin lymphoma
- A 4-year-old diagnosed with a tumor in the kidney called a Wilms tumor
- A 10-year-old diagnosed with cancer of the liver
Some researchers think that problematic variants in the KDM3B gene might be linked to cancers in childhood.
Studying more people who have KDM3B-related syndrome will help us to better understand whether this syndrome is linked to cancer.
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 KDM3B: www.simonssearchlight.org/research/what-we-study/KDM3B
- Simons Searchlight KDM3B Facebook community: www.facebook.com/groups/373300503345036
Sources and References
The content in this guide comes from a published study about KDM3B-related syndrome. Below you can find details about the study, as well as links to summaries or, in some cases, the full article.
- Diets IJ. et al. American Journal of Human Genetics, 104, 758-766, (2019). De novo and inherited pathogenic variants in KDM3B cause intellectual disability, short stature, and facial dysmorphism www.ncbi.nlm.nih.gov/pubmed/30929739
- Mahamdallie, S., Yost, S., Poyastro-Pearson, E., Holt, E., Zachariou, A., Seal, S., Elliott, A., Clarke, M., Warren-Perry, M., … Rahman, N. (2019). Identification of new Wilms tumour predisposition genes: An exome sequencing study. The Lancet Child & Adolescent Health, 3(5), 322-331. https://pubmed.ncbi.nlm.nih.gov/30885698/
- Tabaku, M., Tomori, S., Cullufi, P., Dervishi, E., Paknia, O., & Bauer, P. (2022). A novel de novo pathogenic variant in KDM3B gene at the first Albanian case of Diets-Jongmans syndrome: DIJOS. Molecular Genetics and Metabolism Reports, 33, 100927. https://pubmed.ncbi.nlm.nih.gov/36274669/