Drosophila basement membrane collagen col4a1 mutations cause severe myopathy

► The systemic HANAC phenotype is caused by glycine substitutions in human COL4A1. ► Studies of the mutant muscle are lacking and the pathomechanism remains unknown. ► We identified dominant point mutations in Drosophila col4a1 gene. ► These show intra- and extracellular disorganization in multiple muscle types.