GENE GUIDE

MYT1L-Related Syndrome

This guide is not meant to take the place of medical advice. Please consult with your doctor about your genetic results and health care choices. This Gene Guide was last updated on 2024. As new information comes to light with new research we will update this page. You may find it helpful to share this guide with friends and family members or doctors and teachers of the person who has MYT1L-Related Syndrome.
a doctor sees a patient

MYT1L-related syndrome happens when there are changes to the MYT1L gene. These changes can keep the gene from working as it should.

Key Role

The MYT1L gene plays a key role in the development of the brain.

Symptoms

MYT1L-related syndrome can affect the development of communication skills, social skills, and learning skills. Because MYT1L is important in the development of the brain, many people who have MYT1L-related syndrome have:

  • Motor and speech delay
  • Mild to moderate intellectual disability
  • Excessive hunger and obesity that begins early in life
  • Behavior problems, including hyperactivity and autism spectrum disorder

Our genes contain the instructions, or code, that tell our cells how to grow, develop, and work. Every child gets two copies of the MYT1L gene: one copy from their mother, from the egg, and one copy from their father, from the sperm. In most cases, parents pass on exact copies of the gene to their child. But the process of copying genes is not perfect. A change in the genetic code can lead to physical issues, developmental issues, or both.

Sometimes a random change happens in the sperm or egg. This change to the genetic code is called a ‘de novo’, or new, change. The child can be the first in the family to have the gene change.

De novo changes can take place in any gene. We all have some de novo changes, most of which don’t affect our health. But because MYT1L plays a key role in development, de novo changes in this gene can have a meaningful effect.

Research shows that MYT1L-related syndrome is often the result of a de novo change
in MYT1L. Many parents who have had their genes tested do not have the MYT1L gene change found in their child who has the syndrome. In some cases, MYT1L-related syndrome happens because the gene change was passed down from a parent. This is called dominant inheritance.

Dominant Inheritance

Children have a 50% chance of inheriting the genetic change.

Child who has genetic change in MYT1L gene

Genetic change occurs in egg or sperm after fertilization
Child with de novo genetic change in autism gene

Why does my child have a change in the MYT1L gene?

No parent causes their child’s MYT1L-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.

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 MYT1L-related syndrome depends on the genes of both birth parents.

  • If neither birth parent has the same gene change 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 change in the gene.
  • If one birth parent has the same gene change found in their child, the chance of having another child who has the syndrome is 50 percent.

For a symptom-free sibling, a brother or sister, of someone who has MYT1L-related syndrome, the risk of having a child who has the syndrome depends on the symptom-free sibling’s genes and their parents’ genes.

  • If neither parent has the same gene change found in their child who has the syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who has MYT1L-related syndrome.
  • If one birth parent has the same gene change found in their child who has the syndrome, the symptom-free sibling has a small chance of also having the same gene change. If the symptom-free sibling has the same gene change as their sibling who has the syndrome, the symptom-free sibling’s chance of having a child who has MYT1L-related syndrome is 50 percent.

For a person who has MYT1L-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2018, about 15 people in the world with changes in the MYT1L gene had been described in medical research. The first case of MYT1L-related syndrome was described in 2015. Scientists expect to find more people who have the syndrome as access to genetic testing improves.

People who have MYT1L-related syndrome generally don’t look very different. Appearance can vary and can include some but not all of these features:

  • Long chin
  • Nose that has a broad base and tip
  • Large mouth
  • Narrow eyes
  • Square-shaped trunk

Scientists and doctors have only just begun to study MYT1L-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 MYT1L-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 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.

Sitting and walking

People who have MYT1L-related syndrome can be slow to reach certain milestones, such as sitting and walking. In a study of 10 people, all had motor delays.

Learning

All people who have MYT1L-related syndrome show some degree of intellectual disability. This can range from mild to moderate. Most children need support at school and may need to attend a special school.

Behavior

Some people have autism. In a study of 10 people, 4 had autism. Other common behavior problems include hyperactivity and problems with sleep.

Speech

Many people have speech and language delays.

Growth

  • 85 percent of people were obese.
  • 70 percent of people were reported to have excessive hunger.

Brain 

  • 30 percent of people had seizures.
85%
85 percent of people were obese.
70%
70 percent of people were reported to have excessive hunger.
30%
30 percent of people had seizures.

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.”

Sources and References

The content in this guide comes from published studies about MYT1L-related syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.

  • De Rocker N. et al. Genetics in Medicine, 17, 460-466, (2015). Refinement of the critical 2p25.3 deletion region: the role of MYT1L in intellectual disability and obesity www.ncbi.nlm.nih.gov/pubmed/25232846
  • Mayo S. et al. Genetics in Medicine, 17, 683-684, (2015). Haploinsufficiency of the MYT1L gene causes intellectual disability frequently associated with behavioral disorder www.ncbi.nlm.nih.gov/pubmed/26240977
  • Blanchet P. et al. PLoS Genetics, 13, e1006957, (2017). MYT1L mutations cause intellectual disability and variable obesity by dysregulating gene expression and development of the neuroendocrine hypothalamus
    www.ncbi.nlm.nih.gov/pubmed/28859103

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