Blog – EquiSeq

P4 Allele of MYOZ3

Introduction This blog post explores the P4 allele (S42L) of the equine MYOZ3 gene, which encodes myozenin 3. Portions of this blog post serve as additional sources of information to supplement the MYOZ3 Gene Page. We present data to support the hypothesis that the P4 allele of MYOZ3 (S42L) is damaging. The substitution of leucine…

P2 Allele of MYOT

Introduction This blog post explores the P2 allele (S232P) of the equine MYOT gene, which encodes myotilin. Portions of this blog post serve as additional sources of information to supplement the MYOT Gene Page. We present data to support the hypothesis that the P2 allele of MYOT (S232P) is damaging. The substitution of proline (heterocyclic)…

Genes First!

EquiSeq has released a major revision to the software that powers our website and database. We now present genetic test results starting with the affected gene. Here is an example of the appearance of the new horse profile pages. Figure 1. A horse profile page returning results from EquiSeq. This horse has tested positive for the…

Study of horse genomes explores genetic burden

A team of researchers at the University of Minnesota and the University of California, Davis, have published a landmark study of the predicted genetic burden in horses, based on the analysis of whole genome sequence data from 605 horses (1). They conclude that the genetic load in horses is 1.4 – 2.6 times that of the human population. The authors discuss the unique advantages of the study of horse to understand human phenotypes, especially those associated with athletic performance.

Horse owners have asked us to explain this paper, as it mentions the genetic variants that are in EquiSeq’s panel of DNA tests. Here we review the methods and major findings of this paper. We include background information typically absent from the primary literature in order to make the paper more accessible to non-specialists.

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…

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…

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…

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),…

Peer Review Fails to Identify Errors in Inconclusive Study of Genetic Variants of Equine Muscle Genes

This blog post is a discussion of a paper published by Williams et al. in a recent issue of Equine Veterinary Journal [1]. The paper aims to identify genetic variants that might be responsible for Myofibrillar Myopathy (MFM) in Warmbloods. The authors use a candidate gene approach, searching for variants of eight of the nine genes known…

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…