National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Timothy syndrome


Other Names:
Long QT syndrome 8; LQT8; Long QT syndrome with syndactyly
Categories:
Timothy syndrome is a disorder that affects the heart, digits (toes and fingers), and nervous system (brain and nerves). It is a type of long QT syndrome. Long QT syndrome refers to a prolonged QT interval measurement seen on the electrocardiogram. Symptoms of Timothy syndrome include fusion of the skin between fingers or toes (syndactyly), distinctive facial features, and congenital heart defects. Additional symptoms may include developmental delay, intellectual disability, and autism spectrum disorders.[1][2]

There are two forms of Timothy syndrome, classified based on signs and symptoms. Type 1, known as classic type, includes all of the symptoms described above. Type 2, or atypical type, causes a more severe form of long QT syndrome and does not appear to include syndactyly. Both types are caused by mutations in the CACNA1C gene and are inherited in an autosomal dominant manner.[1][2] Treatment is focused on managing cardiac symptoms. This might include medications such as beta-blockers, placement of defibrillators, and pacemakers.[3]
Last updated: 6/21/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
5%-29% of people have these symptoms
Bronchitis 0012387
Cardiomegaly
Enlarged heart
Increased heart size
[ more ] 		0001640
Generalized hypotonia
Decreased muscle tone
Low muscle tone
[ more ] 		0001290
Hypocalcemia
Low blood calcium levels
0002901
Hypoglycemia
Low blood sugar
0001943
Hypothyroidism
Underactive thyroid
0000821
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Patent ductus arteriosus 0001643
Patent foramen ovale 0001655
Pneumonia 0002090
Seizure 0001250
Tetralogy of Fallot 0001636
Ventricular septal defect
Hole in heart wall separating two lower heart chambers
0001629
Percent of people who have these symptoms is not available through HPO
Autism 0000717
Autosomal dominant inheritance 0000006
Bradycardia
Slow heartbeats
0001662
Cutaneous syndactyly 0012725
Depressed nasal bridge
Depressed bridge of nose
Flat bridge of nose
Flat nasal bridge
Flat, nasal bridge
Flattened nasal bridge
Low nasal bridge
Low nasal root
[ more ] 		0005280
Global developmental delay 0001263
Microdontia
Decreased width of tooth
0000691
Prolonged QT interval 0001657
Recurrent infections
Frequent infections
Frequent, severe infections
Increased frequency of infection
infections, recurrent
Predisposition to infections
Susceptibility to infection
[ more ] 		0002719
Round face
Circular face
Round facial appearance
Round facial shape
[ more ] 		0000311
Sudden death 0001699
Syndactyly
Webbed fingers or toes
0001159
Thin upper lip vermilion
Thin upper lip
0000219
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • Orphanet lists European clinical trials, research studies, and patient registries enrolling people with this condition. 
  • The Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research. Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query".

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Timothy syndrome. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Timothy syndrome. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

Videos/Presentations

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Timothy Syndrome. Genetics Home Reference. 2008; http://ghr.nlm.nih.gov/condition=timothysyndrome. Accessed 6/21/2016.
  2. Carlo Napolitano, MD, PhD, Igor Splawski, PhD, Katherine W Timothy, BS, Raffaella Bloise, MD, Silvia G Priori, MD, PhD.. Timothy syndrome. GeneReviews. July 16, 2015; http://www.ncbi.nlm.nih.gov/books/NBK1403.
  3. Katherine W. Timothy. Timothy Syndrome. NORD. 2005; http://rarediseases.org/rare-diseases/timothy-syndrome/. Accessed 6/21/2016.