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Disease Profile

Timothy syndrome

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

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US Estimated

Europe Estimated

Age of onset

Neonatal

ICD-10

I45.8

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Long QT syndrome 8; LQT8; Long QT syndrome with syndactyly

Categories

Congenital and Genetic Diseases; Heart Diseases

Summary

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]

Symptoms

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.

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

Diagnosis

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.

    Organizations

    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

      Learn more

      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

              References

              1. Timothy Syndrome. Genetics Home Reference. 2008; https://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; https://www.ncbi.nlm.nih.gov/books/NBK1403.
              3. Katherine W. Timothy. Timothy Syndrome. NORD. 2005; https://rarediseases.org/rare-diseases/timothy-syndrome/. Accessed 6/21/2016.