Probable FAD-dependent oxidoreductase; involved in the cellular oxidative stress response (PubMed:27745833). Required for normal sarcomere structure and muscle fiber integrity (By similarity). Binds 1 FAD per subunit. The disease is caused by variants affecting the gene represented in this entry. A mutation in PYROXD1 is the cause of autosomal recessive limb-girdle muscular dystrophy. The affected individual with a homozygous recessive PYROXD1 mutation showed progressive muscle weakness with an onset at the age of 9 years. Initial symptoms included excessive falling while running, with slowly progressive weakness. Difficulty navigating stairs by the age if 18, and loss of ambulation at the age of 37 years. Neurological examination showed proximal symmetrical muscle weakness and wasting, along with calf muscle pseudohypertrophy. Belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family. PYROXD1 subfamily.