What is PSSM?

Polysaccharide Storage Myopathy (PSSM) is a form of equine exercise intolerance characterized by episodes of tying up. Horses with this condition have a particular set of clinical signs, including displays of pain, refusal to move forward, trouble standing for the farrier, and standing “parked out” as if to urinate. All of these are signs of…

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Genetic Linkage of P8 and K1

How can you figure out the chances of different genotypes when breeding horses? Monohybrid Cross It’s easy for one gene. Let’s say that there is a stallion that has one copy of one of the genetic variants associated with PSSM2, the P2 variant (MYOT-S232P). This stallion is heterozygous (n/P2), meaning that he has one normal…

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The K1 Genetic Variant Affects COL6A3, a Gene Encoding a Collagen

Contents Introduction The K1 genetic variant that has been part of EquiSeq’s Myopathy Panel since October 2019 is a missense allele of COL6A3, a gene encoding a collagen [1]. Collagens are a family of proteins that are the main structural components of the connective tissue. Collagens also guide bone formation and play an important role in…

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The P8 Genetic Variant Affects PYROXD1, a Gene Required for Oxidative Defense

Contents Introduction The P8 genetic variant that has been part of EquiSeq’s Myopathy Panel since October 2019 is a missense allele of PYROXD1, a gene required for oxidative defense [1]. Mutations of the human PYROXD1 gene are associated with Myofibrillar Myopathy 8 in humans [1]. The P8 allele of equine PYROXD1 changes an aspartic acid (D) to a histidine (H),…

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Genetic Basis of Exercise Intolerance in Arabians

Paul Szauter, PhD, Chief Scientific Officer of EquiSeq, gave a presentation titled “Genetic Basis of Exercise Intolerance in Arabians” at the Al Khamsa Annual Meeting and Convention in Fayetteville, Arkansas on October 13, 2019. EquiSeq is a company based in Albuquerque, New Mexico, that develops and sells genetic tests for horses. Exercise intolerance is known…

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Mechanism of muscle damage in filaminopathy

Several recent studies address the mechanism of muscle damage in filaminopathy. Filaminopathy is a term that describes muscle disorders resulting from mutations in the FLNC gene, which encodes filamen C. Two different clinical disease states are included in filaminopathy: Myofibrillar Myopathy 5 (MFM5) and Distal Myopathy 4 (DM4). Studies on the mechanism of muscle damage in filaminopathy…

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Genetic Linkage of P2 and P4

How can you figure out the chances of different genotypes when breeding horses? Monohybrid Cross It’s easy for one gene. Let’s say that there is a stallion that has one copy of one of the genetic variants associated with PSSM2, the P2 variant (MYOT-S232P). This stallion is heterozygous (n/P2), meaning that he has one normal…

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Filamin C (FLNC)

Filamins are a family of actin-binding proteins. In humans and other mammals, there are three filamins: filamin A, filamin B, and filamin C. Filamins A and B are widely expressed, while filamin C expression appears limited to skeletal and cardiac muscle. The figure below (adapted from [1]) shows the domain structure of filamin C. Filamins…

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