Myophosphorylase deficiency (glycogen storage disease Type V) in Charolais cattle

Abstract

Extract

Myophosphorylase deficiency (glycogen storage disease Type V) has been diagnosed in Charolais calves in New Zealand. It is manifested as exercise intolerance and recumbency, usually at several weeks of age, due to an inability to mobilise glucose, as glucose phosphate, from glycogen. Affected calves may rise and walk after a rest to again become affected on further exercise. There is rhabdomyolysis and after repeated or severe attacks the calf may remain recumbent and need to be euthanised. The mutant phosphorylase gene has been described. We have established a PCR-RFLP test based on a published method, and have confirmed the diagnosis in affected calves and heterozygous status of sires, dams and other related individuals belonging to an extended family. In addition, several other non-related heterozygotes have been identified in that and another herd. There appears to have been importations of the gene from both England and America.