RXYLT1 and congenital muscular dystrophy: Walker-Warburg syndrome is a rare form of congenital muscular dystrophy (prevalence approximately 1:60,500) [14] with currently 18 known causative genes (POMT1, POMT2, POMGNT1, FKTN, FKRP, LARGE1, ISPD, POMGNT2, GMPPB, DAG1, TMEM5, B3GALNT2, POMK, B3GNT1, DOLK, DPM1, DPM2, DPM3) [15].