TCF20-related disorder is a neurodevelopmental condition that is caused by genetic changes (variants) in the Transcription Factor 20 (TCF20) gene.^1,2 This condition is also known as developmental delay with variable intellectual impairment and behavioural abnormalities (DDVIBA).^1,3 Features of TCF20-related disorder include, but are not limited to, developmental delay, intellectual disability, autism spectrum disorders, attention disorders and movement issues.^1-8 Various organ systems may be affected, resulting in other health issues.² The features and symptoms of TCF20-related disorder may vary widely between individuals.³

These genetic variants in the TCF20 gene typically occur randomly (de novo) before birth and are rarely inherited.¹ TCF20-related disorder can affect both males and females.

Synonyms: Developmental delay with variable intellectual impairment and behavioral abnormalities (DDVIBA).

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

There are no ORPHAcode and ICD-11 classification.

Features and symptoms that have been reported in individuals with TCF20-related disorder include:^1-8

• developmental delay/intellectual disability, including speech issues
• low muscle tone (hypotonia) but in some cases, high muscle tone (hypertonia)
• autism spectrum disorder (ASD)
• attention disorders
• movement issues, including loss of control of voluntary muscles (ataxia), poor balance, poor coordination, abnormal walking (gait disturbances), tremors, and difficulties in controlling and posturing of limbs (dystonia)
• seizures
• sleep disturbances
• gastrointestinal issues
• skeletal issues, including curvature of spine (scoliosis), flat feet (pes planus), deformities of chest (pectus) and feet
• issues with vision
• structural brain anomalies
• variable craniofacial anomalies

Symptoms may vary between individuals. Individuals with TCF20-related disorder may not have all the features and symptoms that have been listed above.

Please speak to your medical team to learn more about the signs and symptoms of TCF20-related disorder.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

TCF20-related disorder is a genetic condition. It is caused by disease-causing genetic changes (variants) in the Transcription Factor 20 (TCF20) gene on Chromosome 22. These genetic variants may include single base changes (sequence variants/ a single letter changes in the genetic code), deletions, duplications.^1,2,4,6 For more information on different types of genetic variants, please refer to  Centre for Genetics Education: Types of genetic variation.

All individuals have two copies (alleles) of the TCF20 gene – one on each chromosome that is inherited from each parent. TCF20-related disorder is an autosomal dominant condition, which means that having a genetic variant in just one of the TCF20 gene copies can result in TCF-20 related disorder.¹

For most individuals with TCF20-related disorder, their genetic variant in TCF20 gene occurs randomly (de novo) prior to birth and is not passed down (inherited) from their parents. In a small number of reported families, the disease-causing TCF-20 alleles had been inherited from a parent who has the genetic variant in some but not all of their cells (this is called genetic mosaicism); the parent often has typical learning abilities and health.^1,2 More information on genetic mosaicism can be found at Centre for Genetics Education: Mosaicism.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information on genetic counselling can be found at:

• Information on Genetic Services
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed

Diagnosis of TCF20-related disorder may be made by genetic testing.

Genetic testing may involve chromosomal microarray analysis (CMA) or exome or genome sequencing to identify genetic changes in the TCF20 gene.

General information about these genetic tests can be found at:

• Pathology Tests Explained: Genome-wide chromosome microarray testing
• Pathology Tests Explained: Whole Genome or Whole Exome Testing for Childhood Syndromes

Please speak to your medical team to learn more about the available diagnostic pathways for TCF20-related disorder.

There is currently no curative treatment for TCF20-related disorder. Treatment is targeted at managing symptoms (symptomatic management) and involves a multidisciplinary care team. Management strategies may include speech and language therapy, physiotherapy, occupational therapy and feeding therapy.³ Individuals may also be assessed and monitored for gastrointestinal issues, scoliosis (curved spine), issues with vision, and seizures.^2,3

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

Healthcare professionals involved in the treatment of TCF20-related disorder may include general practitioners (GP), paediatricians, geneticists, neurologists, gastroenterologists, ophthalmologists, craniofacial surgeons, speech therapists, occupational therapists, physiotherapists, and behavioural therapists.³ The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

We are not aware of any clinical care guidelines for TCF20-related disorder in Australia. If you know of any relevant care guidelines, please let us know via the Contribute page.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance and activities.

We are not aware of any rare disease organisations for TCF20-related disorder in Australia. If you are aware of any rare disease organisation supporting people living with TCF20-related disorder , please let us know via the Contribute page.  If you are interested in starting an Australian organisation, please see Engaged, Ethical and Effective: A Guide for Rare Disease Organisation Leaders in Australia.

Genetics Alliance Australia (GAA) and Syndromes Without A Name (SWAN) Australia may be able to provide some support for families and individuals affected by an undiagnosed or rare genetic condition for which there is no disease specific organisation in Australia.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

TCF20-related disorder varies between individuals, and each person’s experience is unique.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on TCF20-related disorder can be found at:

• Centre for Genetics Education: Facts about health conditions caused by changes in the TCF20 gene.

• Curation results by ClinGen activity – Developmental delay with variable intellectual impairment and behavioral abnormalities
• Online Mendelian Inheritance in Man, OMIM^®: #618430 – Developmental delay with variable intellectual impairment and behavioral abnormalities; DDVIBA

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.