POMT2 and qualitative or quantitative defects of protein involved in O-glycosylation of alpha-dystroglycan: Secondary dystroglycanopathies are more frequent and are caused by recessive mutations in at least six known or putative glycosyltransferases: FKRP, fukutin (FCMD), protein O-mannosyl transferase 1 (POMT1), protein O-mannosyl transferase 2 (POMT2), protein O-mannosyl β-1,2-N-acetylglucosaminyltransferase (POMGnT1), and LARGE [51,52].