Pathogenic and likely pathogenic variants in theCOL6A,COL6A1,COL6A2, andCOL6A3genes have been associated with the Ullrich congenital muscular dystrophy and Bethlem myopathy phenotypes, and they have autosomal dominant and autosomal recessive inheritance patterns.34, 35The variability of clinical significance and complexity of molecular diagnosis in Ullrich's congenital muscular dystrophies is thought to be due to incomplete penetration and autosomal dominant or autosomal recessive mutations.36Briñas et al reported that de novo dominant mutations were seen in 61% of their patients. Here, COL6A1 is linked to Bethlem myopathy.