According to a Japanese study from 2007, Bethlem myopathy 1 affects about 1 in 200,000 people.<ref name="Okada2007">{{Cite journal |last=Okada |first=M. ''et|last2=Kawahara al''|first2=G. (|last3=Noguchi |first3=S. |last4=Sugie |first4=K. |last5=Murayama |first5=K. |last6=Nonaka |first6=I. |last7=Hayashi |first7=Y. K. |last8=Nishino |first8=I. |date=2007)-09-04 |title=Primary collagen VI deficiency is the second most common congenital muscular dystrophy in Japan |url=https://pubmed.ncbi.nlm.nih.gov/17785673/ Neurolog|journal=Neurology |volume=69: |issue=10 |pages=1035–1042 |doi=10.1212/01.wnl.0000271387.10404.4e |issn=1526-632X |pmid=17785673}}</ref> A 2009 study, concerning the prevalence of genetic muscle disease in [[Northern England]], estimated the prevalence of Bethlem myopathy 1 to be at 0.77:100,000.<ref>{{Cite journal|last1=Norwood|first1=Fiona L. M.|last2=Harling|first2=Chris|last3=Chinnery|first3=Patrick F.|last4=Eagle|first4=Michelle|last5=Bushby|first5=Kate|last6=Straub|first6=Volker|date=2009|title=Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population|journal=Brain: A Journal of Neurology|volume=132|issue=Pt 11|pages=3175–3186|doi=10.1093/brain/awp236|issn=1460-2156|pmc=4038491|pmid=19767415}}</ref> Together with Ullrich congenital muscular dystrophy 1, Bethlem myopathy 1 is believed to be underdiagnosed. Both conditions have been described in individuals from a variety of ethnic backgrounds.<ref>{{Cite book|last1=Lampe|first1=Anne Katrin|title=Collagen Type VI-Related Disorders|date=1993|url=http://www.ncbi.nlm.nih.gov/books/NBK1503/|work=GeneReviews®|editor-last=Adam|editor-first=Margaret P.|place=Seattle (WA)|publisher=University of Washington, Seattle|pmid=20301676|access-date=2020-10-19|last2=Flanigan|first2=Kevin M.|last3=Bushby|first3=Katharine Mary|last4=Hicks|first4=Debbie|chapter=Collagen VI-Related Dystrophies |editor2-last=Ardinger|editor2-first=Holly H.|editor3-last=Pagon|editor3-first=Roberta A.|editor4-last=Wallace|editor4-first=Stephanie E.}}</ref> Bethlem myopathy 2 affects less than 1 in 1,000,000 people.<ref name=":2" />