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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…

In human patients, mutations in the gene encoding filamin C (FLNC) are associated with Myofibrillar Myopathy 5 [1]. In a prior blog post, we reviewed the human mutations in FLNC associated with the disease state Myofibrillar Myopathy 5 (MFM5) and various cardiomyopathies. We also presented the specific changes associated with the equine P3 allele of…

Is PSSM2 genetic? By genetic, we mean that it is an inherited condition, transmitted from parents to offspring rather than resulting exclusively from environmental conditions, such as diet or exposure to toxins or pathogens. What do we mean by PSSM2? PSSM2 is an abbreviation for Polysaccharide Storage Myopathy type 2 [1]. It is a disease…

Myotilin is a muscle protein encoded by the MYOT gene. Myotilin is a structural protein of muscle that localizes to the Z discs. Myotilin contains two Immunoglobulin-like (Ig-like) domains similar to those of palladin, myopalladin, titin, and other proteins. The amino-terminal portion of myotilin contains a large number of serine residues and is not similar…

This was written in response to a post on the PSSM Forum on Facebook. Negative nitrogen balance is a normal process that is helpful under the right circumstances. It is not confined to PSSM horses. You have certainly experienced it yourself. There are some circumstances under which you cannot consume enough dietary protein to meet…

Polysaccharide Storage Myopathy type 2 (PSSM2) is a type of exercise intolerance seen in horses. Polysaccharide Storage Myopathy type 2 (PSSM2) is a disease state defined by symptoms of exercise intolerance, absence of the genetic variant GYS1-R309H (P1) that is associated with Polysaccharide Storage Myopathy type 1 (PSSM1) [1], and abnormalities observed in muscle biopsy.…

Polysaccharide Storage Myopathy type 1 (PSSM1) is a disease state in horses caused by an inherited defect in glycogen metabolism. Polysaccharide Storage Myopathy type 1 (PSSM1) is a form of exercise intolerance. Horses with Polysaccharide Storage Myopathy type 1 (PSSM1) exhibit exercise-induced symptoms including reluctance to move, pain, stiffness, tremors, and profuse sweating. Serum creatine…

Jax is n/P1, n/P2, n/Px. I got him when he was an unbroke 4 year old, and he was quirky that first year but then had over 2 great years of riding. He didn’t go highly symptomatic until he was 8 years old, but right as he turned 8 he crashed hard. Early symptoms included…

This was written in response to a post on the PSSM Forum on Facebook. Negative nitrogen balance is a normal process that is helpful under the right circumstances. It is not confined to PSSM horses. You have certainly experienced it yourself. There are some circumstances under which you cannot consume enough dietary protein to meet…