TNNT3 and congenital myopathy with cores: Whilst the rate of gene discovery is slowing, one growth area in congenital myopathy genetics has been the identification of recessive congenital myopathies associated with pathogenic variants in genes previously associated only with dominant disease, namelyCACNA1S,SCN4A,TNNT3, andTTN. Cases of congenital myopathy presentingin utero (sometimes as early as the first trimester with foetal akinesia and associated abnormalities, including multiple joint contractures, and arthrogryposis) are also increasingly recognised3.