Gapmer and Mixmer Antisense Oligonucleotides to Selectively Suppress the Mutant Allele in COL6A Genes in Dominant Ullrich Congenital Muscular Dystrophy.

Allele-specific gene silencing with antisense oligonucleotides (ASOs) or small interfering RNA (siRNA) is a promising strategy for disorders driven by dominant gain-of-function effects. We here present two antisense approaches, gapmer and mixmer ASOs, to mitigate the dominant-negative mechanism underlying Ullrich congenital muscular dystrophy (UCMD) caused by recurrent COL6A3 mutations. We outline the details of methods that our lab has used. The methods comprise the rational ASO design (classical gapmers and mixmers to enhance allele selectivity), in vitro evaluation of allele-specific mRNA knockdown, and protein-level functional assessment. Patient-derived dermal fibroblasts harboring COL6A3 c.6210+1G>A or c.6135_6152del were used as cellular models.