Whereas the atrophy or hypotrophy of type I fibres is a common feature in CM [2], the marked smallness of type II fibres observed in MYL1‐congenital myopathy rarely occurs in genetic myopathies, specifically in MYH2‐related ones [25, 35, 39, 40]. The gene discussed is MYL1; the disease is congenital myopathy with cores.