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TTN gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TTN gene

The TTN gene provides instructions for making titin, a giant protein essential for the structure, flexibility, and contraction of skeletal and cardiac muscles.

Normal Function

The TTN gene provides instructions for making a very large protein called titin. This protein plays an important role in skeletal muscles, which the body uses for movement, and in heart (cardiac) muscle. Within muscle cells, titin is an essential component of structures called sarcomeres, the basic units of muscle contraction.

Titin has several functions within sarcomeres:

  • Provides structure, flexibility, and stability to cell structures.
  • Interacts with other muscle proteins, including actin and myosin, to keep components in place during contraction and relaxation.
  • Contains a spring-like region that allows muscles to stretch.
  • Plays a role in chemical signaling and in assembling new sarcomeres.

Health Conditions Related to Genetic Changes

Centronuclear myopathy

Several variants in the TTN gene have been found to cause centronuclear myopathy, characterized by skeletal muscle weakness. These variants typically result in the production of an abnormal protein with reduced or altered activity, or prevent the production of titin entirely. A shortage of normal titin leads to sarcomere dysfunction, preventing muscle cells from contracting and relaxing normally.

Early-onset myopathy with fatal cardiomyopathy

Variants in the TTN gene have been identified in people with early-onset myopathy with fatal cardiomyopathy (EOMFC). These genetic changes occur near the end of the gene and lead to an abnormally short version of the titin protein. This disrupts sarcomere function, preventing skeletal and cardiac muscle from working normally, leading to skeletal muscle weakness and dilated cardiomyopathy.

Nonsyndromic dilated cardiomyopathy

TTN gene variants account for approximately 15 to 20 percent of all cases of nonsyndromic dilated cardiomyopathy, a condition that weakens and enlarges the heart. These variants lead to the production of an abnormal titin protein, particularly in cardiac muscle, which impairs sarcomere function and disrupts chemical signaling, reducing the heart's ability to contract.

Hereditary myopathy with early respiratory failure

Variants in the TTN gene, specifically in exon 344, cause hereditary myopathy with early respiratory failure (HMERF). These changes alter the FN3 119 domain of the titin protein and are thought to impair the protein's folding into its normal 3-dimensional shape, leading to muscle damage in skeletal and respiratory muscles.

Tibial muscular dystrophy

Variants in the TTN gene have been identified in people with tibial muscular dystrophy, which primarily affects the muscles at the front of the lower leg. These variants alter the ability of titin to interact with other proteins within sarcomeres, likely impairing muscle fiber maintenance or contraction.

Other disorders

Early-onset forms of titin-related muscle disorders are often grouped as congenital titinopathy. Features may include reduced fetal movement, low muscle tone (hypotonia), joint deformities (contractures), and muscle weakness in the neck, arms, or legs. Scoliosis and difficulty breathing are also common. Researchers suspect that the specific isoform of titin affected by the gene variant helps determine the set of features in affected individuals.

Other Names for This Gene

  • CMH9
  • CMPD4
  • CONNECTIN
  • EOMFC
  • LGMD2J
  • MYLK5
  • TITIN_HUMAN
  • TMD

Frequently Asked Questions

nswer: Symptoms can vary depending on the specific condition. For centronuclear myopathy, skeletal muscle weakness is the primary feature. In early-onset myopathy with fatal cardiomyopathy (EOMFC), severe skeletal muscle weakness and dilated cardiomyopathy (enlarged heart) are present from early life. For nonsyndromic dilated cardiomyopathy, symptoms like shortness of breath, fatigue, and swelling can appear at various ages due to the heart's reduced pumping ability.
nswer: Treatment is primarily supportive and aims to manage symptoms. For muscle weakness, physical therapy, occupational therapy, and assistive devices may be recommended. For cardiomyopathy, medications to improve heart function, manage fluid retention, or regulate heart rhythm are common. In some severe cases, pacemakers, defibrillators, or heart transplantation may be considered. Regular monitoring by a cardiologist and neurologist is essential.
nswer: The inheritance pattern for TTN gene mutations can vary, but many are inherited in an autosomal dominant manner. This means that if one parent has a pathogenic TTN mutation, there is a 50% chance with each pregnancy that their child will inherit the mutation and potentially develop the associated condition. Genetic counseling can provide a personalized risk assessment based on the specific mutation and family history.
nswer: Diagnosis typically involves genetic testing, often performed after clinical evaluation for symptoms of muscle weakness or heart disease. Identifying a TTN mutation confirms the genetic cause of the condition. For family members, genetic counseling is crucial to understand the inheritance pattern and the risk of developing the condition or being a carrier, as TTN-related conditions can be inherited.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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