Patients manifest a consistently severe phenotype characterised by a paucity of early symptoms followed by an accelerated progression to a severe form of UCMD, except for one patient with somatic mosaicism for this <i>COL6A1</i> intron 11 variant who manifests a milder phenotype consistent with Bethlem muscular dystrophy. The gene discussed is COL6A1; the disease is Ullrich congenital muscular dystrophy.