Features include always present findings: Elevated creatine kinase (muscle enzyme) (elevated circulating creatine kinase concentration), Rhabdomyolysis, Difficulty climbing stairs, and Hip contracture and others; and common findings: Fatty replacement of ventricular myocardial tissue, Kyphoscoliosis, Delayed gross motor development, and Ankle contracture and others. 20 total HPO annotations.

TNNT1 function has not been fully characterized.

Nemaline myopathy 5B, autosomal recessive, childhood-onset is associated with mutations in the TNNT1 gene on chromosome 19.

Genetic testing for TNNT1 is available. Testing is considered confirmatory for diagnosis.

Phenotype severity distribution: 7 always present features, 11 common features.