Congenital Titinopathy: Comprehensive characterization and pathogenic insights

Area of Science:

• Genetics
• Neuromuscular Disorders
• Molecular Biology

Background:

• Congenital titinopathy is an emerging neuromuscular disorder with significant diagnostic challenges.
• Understanding the clinical spectrum and underlying genetic basis is crucial for patient management.

Purpose of the Study:

• To provide a comprehensive clinical characterization of congenital titinopathy.
• To facilitate the diagnosis and management of this disorder.
• To gain insights into the pathogenesis of congenital titinopathy.

Main Methods:

• Massively parallel sequencing identified pathogenic TTN mutations in 30 patients from 27 families.
• Detailed analysis of clinical, histopathological, and imaging features was performed.
• Western blot analysis assessed titin protein size.

Main Results:

• Patients presented with early hypotonia/contractures, scoliosis, and respiratory insufficiency; limb weakness was slowly progressive.
• Cardiac involvement occurred in 46% of patients, with dilated cardiomyopathy in relatives.
• Histopathology revealed fiber size variation, internalized nuclei, and cores; MRI showed specific muscle involvement.

Conclusions:

• This study establishes a detailed clinical reference dataset for congenital titinopathy.
• Findings provide insights into disease pathogenesis, suggesting involvement of developmental titin isoforms.
• The data will greatly facilitate diagnostic confirmation and management of affected individuals.