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Discussion on Research Summary: Cause of PSSM identified?
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Moderator:
DrO
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Posted on Tuesday, Apr 15, 2008 - 7:39 am:
Despite much research in the past 10 years there are many ongoing questions about the nature of the various tying up synDrOmes that effect horses. Defining the nature of the disease is the most important step in defining a disease and in the case of a genetic problem the first step toward eradication. Concerning PSSM this may be that important step. In this report a point mutation in the genome encoding for a enzyme that aids in glycogen synthesis has been found. This mutation speeds up the glycogen formation but it is not clear from this review that the glycogen is abnormal, a previously described feature of PSSM. I think I will wait just for some conformation of my understanding of this summary before putting this in the article. Anyone get this journal?
DrO
Genomics. 2008 Mar 19;
Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis.
McCue ME, Valberg SJ, Miller MB, Wade C, Dimauro S, Akman HO, Mickelson JR.
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA.
Polysaccharide storage myopathy (PSSM) is a novel glycogenosis in horses characterized by abnormal glycogen accumulation in skeletal muscle and muscle damage with exertion. It is unlike glycogen storage diseases resulting from known defects in glycogenolysis, glycolysis, and glycogen synthesis that have been described in humans and domestic animals. A genome-wide association identified GYS1, encoding skeletal muscle glycogen synthase (GS), as a candidate gene for PSSM. DNA sequence analysis revealed a mutation resulting in an arginine-to-histidine substitution in a highly conserved region of GS. Functional analysis demonstrated an elevated GS activity in PSSM horses, and haplotype analysis and allele age estimation demonstrated that this mutation is identical by descent among horse breeds. This is the first report of a gain-of-function mutation in GYS1 resulting in a glycogenosis.
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