Symbol PYGM HUGO 9726 RefSeq NM_005609 | Entrez 5837 OMIM 608455 UniProt P11217 | |
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Myophosphorylase is the muscle isoform of the enzyme glycogen phosphorylase. This enzyme helps break down glycogen (a form of stored carbohydrate) into glucose-1-phosphate (not glucose), so that it can be utilized within the muscle cell.
Clinical significance
A deficiency is associated with Glycogen storage disease type V, also known as "McArdle's Syndrome".
A case study suggested that a deficiency in myophosphorylase may be linked with cognitive impairment. Besides muscle, this isoform is present in astrocytes, where it plays a key role in neural energy metabolism. A 55-year-old woman with McArdle disease has expressed cognitive impairment with bilateral dysfunction of prefrontal and frontal cortex. Further studies are needed to assess the validity of this claim.