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TNNI2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TNNI2 gene

The TNNI2 gene provides instructions for making a form of the troponin I protein, which is essential for the contraction of skeletal muscles.

Normal Function

The TNNI2 gene provides instructions for making one form of a protein called troponin I. The troponin I protein produced from the TNNI2 gene is found in skeletal muscles, which are the muscles used for movement. Troponin I is one of three proteins that make up the troponin complex in muscle cells. The troponin complex, along with calcium, helps regulate muscle tensing (contraction).

The troponin complex is part of a structure called the sarcomere, which is the basic unit of muscle contraction. Sarcomeres contain thick and thin filaments. The overlapping thick and thin filaments attach (bind) to each other and release, which allows the filaments to move relative to one another so that muscles can contract.

When calcium levels are low, the troponin complex blocks the binding between the thick and thin filaments that is needed for muscle contraction. An increase in calcium levels causes structural changes in the troponin complex, which exposes the binding sites and allows the thick and thin filaments to interact, leading to muscle contraction.

Health Conditions Related to Genetic Changes

Sheldon-Hall syndrome

At least eight TNNI2 gene mutations have been identified in people with Sheldon-Hall syndrome. This disorder affects muscle and skeletal development before birth and is characterized by joint deformities (contractures) that restrict movement in the hands and feet. Researchers suggest that the TNNI2 gene mutations that cause Sheldon-Hall syndrome may prevent the troponin complex from blocking thick and thin filament binding to control muscle contractions, resulting in the contractures and other muscle and skeletal abnormalities associated with Sheldon-Hall syndrome.

Other Names for This Gene

  • AMCD2B
  • DA2B
  • FSSV
  • fsTnI
  • troponin I fast twitch 2
  • troponin I type 2 (skeletal, fast)
  • troponin I, fast skeletal muscle
  • troponin I, fast skeletal muscle isoform 1
  • troponin I, fast skeletal muscle isoform 2
  • troponin I, fast-twitch isoform
  • troponin I, fast-twitch skeletal muscle isoform
  • troponin I, skeletal, fast

Frequently Asked Questions

Diagnosis of Sheldon-Hall syndrome is typically based on the characteristic physical findings of joint contractures at birth. Genetic testing for mutations in the TNNI2 gene is essential to confirm the diagnosis and distinguish it from other conditions with similar symptoms. This testing usually involves analyzing a blood sample for specific gene changes.
Sheldon-Hall syndrome caused by TNNI2 mutations is inherited in an autosomal dominant pattern. This means if you carry one copy of the mutated gene, each of your children has a 50% chance of inheriting the mutation and potentially developing the syndrome. Genetic counseling can help you understand these risks and discuss family planning.
Sheldon-Hall syndrome caused by TNNI2 gene mutations primarily presents with multiple joint contractures, meaning joints are fixed in bent or straightened positions, restricting movement. These are often noticeable at birth, affecting the hands and feet, and sometimes larger joints. Other signs can include muscle weakness and skeletal abnormalities.
Management of Sheldon-Hall syndrome focuses on improving joint mobility and function. This often includes physical therapy, occupational therapy, and stretching exercises to help loosen contractures. Serial casting or splinting may be used to gradually correct joint positions. In some cases, surgical interventions might be considered to release severe contractures.
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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