DAG1 and neuromuscular disease caused by qualitative or quantitative defects of alpha-dystroglycan: Later, more systematic studies with random insertional mutagenesis using gene trapping in haploid HAP1 cells and selection with Lassa virus binding to the matriglycan on α-dystroglycan revealed several known (e.g., POMT1/2, B3GNT1) and unknown (e.g., SLC35A1, ST3GAL4, B3GALNT2) glycogenes involved in glycosylation of α-dystroglycan and underlying dystroglycanopathies (107).