GENE GUIDE

TCF7L2-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 in 2025. 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 TCF7L2-Related Syndrome.
a doctor sees a patient

TCF7L2-related syndrome is also called TCF7L2-related neurodevelopmental disorder (TRND). For this webpage, we will be using the name TCF7L2-related syndrome to encompass the wide range of variants observed in the people identified.

TCF7L2-related syndrome happens when there are changes in the TCF7L2 gene. These changes can keep the gene from working as it should.

Other genetic variations in the TCF7L2 gene can cause diabetes without a neurodevelopmental condition. Some genetic variations in this gene are linked to cancer.

The information below covers gene changes that lead to the neurodevelopmental condition.

Key Role

The TCF7L2 gene is important for communication between cells.

Symptoms

Because the TCF7L2 gene is important for brain activity, many people who have TCF7L2-related syndrome have:

  • Developmental delay
  • Intellectual disability
  • Attention-deficit/hyperactivity disorder, also called ADHD
  • Speech delay
  • Delay of motor development
  • Autism spectrum disorder
  • Sleep issues
  • Nearsightedness

TCF7L2-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 TCF7L2 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 TCF7L2 plays a key role in development, de novo variants in this gene can have a meaningful effect. 

Research shows that TCF7L2-related syndrome is often the result of a de novo variant in TCF7L2. Many parents who have had their genes tested do not have the TCF7L2 genetic variant found in their child who has the syndrome. In some cases, TCF7L2-related syndrome happens because the genetic variant was passed down from a parent.

Autosomal dominant conditions

TCF7L2-related syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in TCF7L2 they will likely have symptoms of TCF7L2-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

GENE / gene
GENE / gene
Genetic variant that happens in sperm or egg, or after fertilization
GENE / gene
Child with de novo genetic variant
gene / gene
Non-carrier child
gene / gene
Non-carrier child

No parent causes their child’s TCF7L2-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 foreseen 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 TCF7L2-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 TCF7L2-related syndrome, the sibling’s risk of having a child who has TCF7L2-related syndrome depends on the sibling’s genes and their parents’ genes. 

  • If neither parent has the same genetic variant causing TCF7L2-related syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit TCF7L2-related syndrome. 
  • If one biological parent has the same genetic variant causing TCF7L2-related 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 TCF7L2-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2024, at least 17 people with TCF7L2-related syndrome have been described in medical research.

TCF7L2-related syndrome is very rare, and it is unknown if people with this condition look different. Some people have excessive hair growth on the body and a flattening of the back of the head as an infant.

Scientists and doctors have only just begun to study TCF7L2-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 TCF7L2-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: 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.

Speech and learning

Most people with TCF7L2-related syndrome had developmental delays, and some had intellectual disabilities, or were minimally verbal or non-verbal. The age of first words ranged from 18 months to 7 years.

  • 9 out of 17 people had intellectual disability (53 percent)
  • 12 out of 17 people were minimally verbal or non-verbal (71 percent)
53%
9 out of 17 people had intellectual disability.
71%
12 out of 17 people were minimally verbal or non-verbal.

Behavior

People with TCF7L2-related syndrome had behavioral issues, such as autism or features of autism, attention-deficit/hyperactivity disorder (ADHD), sleep difficulties, anxiety, or aggression.

  • 4 out of 11 people had autism or features of autism (36 percent)
  • 4 out of 11 people had ADHD (36 percent)
  • 4 out of 11 people had sleep difficulties (36 percent)

Brain

Some people with TCF7L2-related syndrome had seizures, lower than average muscle tone (hypotonia), and brain changes observed on magnetic resonance imaging (MRI).

  • 1 out of 11 people had seizures (9 percent)
  • 3 out of 11 people had hypotonia (27 percent)
  • 5 out of 10 people had brain changes observed on MRI (50 percent)
Human head showing brain outline
9%
1 out of 11 people had seizures.
27%
3 out of 11 people had hypotonia.
50%
5 out of 10 people had brain changes observed on MRI.

Other medical features

People with TCF7L2-related syndrome had vision issues, such as nearsightedness (myopia) or crossed eyes (strabismus), and musculoskeletal issues.

  • 7 out of 11 people had vision issues (64 percent)
  • 6 out of 11 people had musculoskeletal issues (55 percent)

Where can I find support and resources?

TRND Network

The TRND Network is dedicated to supporting patients and their loved ones by providing advocacy and support, advancing research, and creating collaboration between researchers and patients.

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 TCF7L2-related syndrome.

  • Dias, C., Pfundt, R., Kleefstra, T., Shuurs-Hoeijmakers, J., Boon, E. M. J., van Hagen, J. M., Zwijnenburg, P., Weiss, M. M., Keren, B., … & Rodan, L. H. (2021). De novo variants in TCF7L2 are associated with a syndromic neurodevelopmental disorder. American Journal of Medical Genetics Part A, 185(8), 2384-2390. https://pubmed.ncbi.nlm.nih.gov/34003604/

Stay connected with Simons Searchlight

Join our newsletter to receive updates