TNNT1 and congenital myopathy with cores: Nemaline myopathy is one of the most common forms of congenital myopathy, with a prevalence that differs between studies (overall <20% of all congenital myopathies).1, 2, 3 Seven genes related to this disease encode proteins involved in muscle contraction: ACTA1, NEB, TPM3, TPM2, CFL2, TNNT1, and LMOD3. 1, 4, 5KBTBD13, KLHL40, and KLHL41 genes have also been associated with nemaline myopathy but encode proteins contributing to transcriptional regulation and degradation.1