Genetic testing in horses involves the analysis of DNA to identify specific genetic markers that can provide information about an individual horse’s traits, predispositions, and lineage. This process can reveal insights into inherited diseases, coat color variations, and performance-related attributes. Genetic testing is utilized in breeding programs to select for desirable traits and to avoid the propagation of genetic disorders. Common tests include those for diseases such as hyperkalemic periodic paralysis (HYPP) and severe combined immunodeficiency (SCID). This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and implications of genetic testing in equine science.
Brown C, Stefaniuk-Szmukier M, Decloedt A, Beijerink N, Hamilton NA, Velie BD.Congenital heart defects (CHDs) can have profound and potentially life-threatening consequences on horses' health and performance capability. While CHDs are rare in the general horse population, the Arabian breed is disproportionately overrepresented and thus is widely suspected to be genetically predisposed. This review discusses the most common CHDs in Arabian horses, including ventricular septal defect (VSD), tetralogy of Fallot (TOF), patent duct arteriosus (PDA), tricuspid valve atresia (TVA) and atrial septal defect (ASD). This review also explores how future research into the genetic fa...
De Coster T, Zhao Y, Tšuiko O, Demyda-Peyrás S, Van Soom A, Vermeesch JR, Smits K.In different species, embryonic aneuploidies and genome-wide errors are a major cause of developmental failure. The increasing number of equine embryos being produced worldwide provides the opportunity to characterize and rank or select embryos based on their genetic profile prior to transfer. Here, we explored the possibility of generic, genome-wide preimplantation genetic testing concurrently for aneuploidies (PGT-A) and monogenic (PGT-M) traits and diseases in the horse, meanwhile assessing the incidence and spectrum of chromosomal and genome-wide errors in in vitro-produced equine embryos....
Faccin M, Landsgaard KA, Milliron SM, Jennings AH, Keith Chaffin M, Giaretta PR, Rech RR.A 1.5-year-old American quarter horse gelding (case 1) and an 11-month-old American quarter horse filly (case 2) were presented for acute onset pelvic lameness and lethargy. Case 1 had nasal discharge, while case 2 developed rapid muscle atrophy. Both horses had elevated serum creatine kinase activity. The horses showed similar polyphasic histiocytic and lymphoplasmacytic myositis with necrosis, mineralization, and regeneration. Additionally, case 1 had Streptococcus equi subsp. equi-induced suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy...
Esdaile E, Knickelbein KE, Donnelly CG, Ferneding M, Motta MJ, Story BD, Avila F, Finno CJ, Gilger BC, Sandmeyer L, Thomasy S, Bellone RR.Congenital stationary night blindness (CSNB) is an ocular disorder characterized by nyctalopia. An autosomal recessive missense mutation in glutamate metabotropic receptor 6 (GRM6 c.533C>T, p.(Thr178Met)), called CSNB2, was previously identified in one Tennessee Walking Horse and predicted to reduce binding affinity of the neurotransmitter glutamate, impacting the retinal rod ON-bipolar cell signaling pathway. Thus, the first aim was to identify the allele frequency (AF) of CSNB2 in breeds with reported cases of CSNB and breeds closely related to the Tennessee Walking Horse. The second aim ...
McCue PM, Matthews PM, Prell MJ, Bellone RR, Allen H.Genetic testing is required for the registration of foals of most equine breeds. Objective: To describe two clinical cases of marked delayed embryonic development or delayed fertilisation in pregnancies generated by embryo transfer. Methods: Case report. Methods: Donor mares were inseminated with semen from one stallion during one oestrous cycle and semen from a different stallion on the subsequent oestrous cycle. Embryo(s) were collected 8 days after ovulation during the second oestrous cycle and transferred into synchronised recipient mares. Genetic testing was performed to determine paren...
Wobbe M, Reinhardt F, Reents R, Tetens J, Stock KF.Awareness of breeders of Warmblood Fragile Foal Syndrome (WFFS) increased after a widely discussed case in the USA in 2018. The hereditary connective tissue disorder, first described by a US research group in 2011 and for which a commercial genetic test exists since 2013, is caused by a point mutation in the PLOD1 gene, inherited autosomal recessively. Extension of molecular genetic testing and reporting of test results of organized horse breeders to their studbooks implies new opportunities for analyses. In Germany, data are centrally accessible through the integrated equine data base allowin...
Valberg SJ, Henry ML, Herrick KL, Velez-Irizarry D, Finno CJ, Petersen JL.Genetic tests for variants in MYOT (P2; rs1138656462), FLNC (P3a; rs1139799323 or P3b; rs1142918816) and MYOZ3 (P4; rs1142544043) genes are offered commercially to diagnose myofibrillar myopathy (MFM) and type 2 polysaccharide storage myopathy (PSSM2) in Quarter Horses (QH). Objective: To determine if PSSM2-QH has histopathological features of MFM. To compare genotype and allele frequencies of variants P2, P3, P4 between control-QH and PSSM2-QH diagnosed by histopathology. Methods: Retrospective cross-sectional. Methods: The study includes a total of 229 healthy control-QH, 163 PSSM2-QH GYS1 ...
Patterson Rosa L, Troop TW, Martin K, Vierra M, Foster G, Lundquist E, Brooks SA, Lafayette C.Hereditary Equine Regional Dermal Asthenia (HERDA) is an autosomal recessive condition present in the American Quarter Horse and other related breeds. Resulting from a mutation in the peptidyl-prolyl cis-trans isomerase B (PPIB) gene, HERDA is homologous to Ehlers-Danlos syndrome in humans. Characterized by fragile, hyperelastic, skin, HERDA affected horses often present first with slow-healing wounds usually on the dorsum, and resulting in atrophic scars, seromas, and ulcers. As there is no treatment for the condition affected horses are typically reported to be unrideable, and if persisten...
Finno CJ.Hoof wall separation disease (HWSD) is a genetic defect in Connemara ponies characterised by separation and cracking of the dorsal hoof wall. The disease can result in chronic inflammation, severe lameness and laminitis. Affected ponies typically show clinical signs within the first six months of life. The disease is inherited as an autosomal recessive trait. The genetic mutation is a frameshift mutation in the gene SERPINB11, (c.504_505insC). Carriers are completely normal, only ponies that are homozygous for the mutation will have clinical signs of the disease. Within the Connemara breed, ca...
Fontanel M, Todd E, Drabbe A, Ropka-Molik K, Stefaniuk-Szmukier M, Myćka G, Velie BD.Arabian horses are not only one of the most ancient breeds in the world, but they are also one of the most appreciated racehorse breeds today. The breed generates attention for their phenomenal endurance ability and their capability for gallop racing. Consequently, genetic testing to select the best individuals is attracting ever increasing interests from the Arabian industry. As such, the aim of this study was to further investigate associations between performance and variation at candidate genes suspected of having a key role in Arabian gallop racing performance. Generalized linear models w...
Bellone RR.Horses perform in a variety of disciplines that are visually demanding, and any disease impacting the eye has the potential to threaten vision and thus the utility of the horse. Advances in equine genetics have enabled the understanding of some inherited ocular disorders and ocular manifestations and are enabling cross-species comparisons. Genetic testing for multiple congenital ocular anomalies, congenital stationary night blindness, equine recurrent uveitis, and squamous cell carcinoma can identify horses with or at risk for disease and thus can assist in clinical management and breeding dec...
Tozaki T, Ohnuma A, Kikuchi M, Ishige T, Kakoi H, Hirota KI, Kusano K, Nagata SI.Gene doping, an activity which abuses and misuses gene therapy, is a major concern in sports and horseracing industries. Effective methods capable of detecting and monitoring gene doping are urgently needed. Although several PCR-based methods that detect transgenes have been developed, many of them focus only on a single transgene. However, numerous genes associated with athletic ability may be potential gene-doping material. Here, we developed a detection method that targets multiple transgenes. We targeted 12 genes that may be associated with athletic performance and designed two TaqMan prob...
Kolb DS, Klein C.Congenital hydrocephalus has been reported for a number of horse breeds, and for Friesian horses this condition has been associated with a nonsense mutation of B3GALNT2. We report the first case of congenital hydrocephalus associated with the said mutation in a Belgian draft horse. Genetic testing and consideration of the testing results in breeding programs are warranted. Hydrocéphalie congénitale chez un cheval de trait Belge associée à une mutation non-sens de B3GALNT2. L’hydrocéphalie congénitale a été signalée pour plusieurs races de chevaux et, pour les chevaux Frisons, cette ...
Cavalleri JM, Metzger J, Hellige M, Lampe V, Stuckenschneider K, Tipold A, Beineke A, Becker K, Distl O, Feige K.Cerebellar abiotrophy (CA) is a rare but significant disease in Arabian horses caused by progressive death of the Purkinje cells resulting in cerebellar ataxia characterized by a typical head tremor, jerky head movements and lack of menace response. The specific role of magnetic resonance imaging (MRI) to support clinical diagnosis has been discussed. However, as yet MR imaging has only been described in one equine CA case. The role of MR morphometry in this regard is currently unknown. Due to the hereditary nature of the disease, genetic testing can support the diagnosis of CA. Therefore, the...
Hauswirth R, Jude R, Haase B, Bellone RR, Archer S, Holl H, Brooks SA, Tozaki T, Penedo MC, Rieder S, Leeb T.Variants in the EDNRB, KIT, MITF, PAX3 and TRPM1 genes are known to cause white spotting phenotypes in horses, which can range from the common white markings up to completely white horses. In this study, we investigated these candidate genes in 169 horses with white spotting phenotypes not explained by the previously described variants. We identified a novel missense variant, PAX3:p.Pro32Arg, in Appaloosa horses with a splashed white phenotype in addition to their leopard complex spotting patterns. We also found three novel variants in the KIT gene. The splice site variant c.1346+1G>A occur...
Nikiforov TT, Rendle RB, Goelet P, Rogers YH, Kotewicz ML, Anderson S, Trainor GL, Knapp MR.A new method for typing single nucleotide polymorphisms in DNA is described. In this method, specific fragments of genomic DNA containing the polymorphic site(s) are first amplified by the polymerase chain reaction (PCR) using one regular and one phosphorothioate-modified primer. The double-stranded PCR product is rendered single-stranded by treatment with the enzyme T7 gene 6 exonuclease, and captured onto individual wells of a 96 well polystyrene plate by hybridization to an immobilized oligonucleotide primer. This primer is designed to hybridize to the single-stranded target DNA immediately...
The Journal of heredityJanuary 1, 1976
Volume 67, Issue 1 6-10 doi: 10.1093/oxfordjournals.jhered.a108667
Trommershausen-Smith A, Suzuki Y, Stormont C.The chestnut rule in equine coat-color genetics asserts that the inter se mating of chestnut horses never produces bay, black, brown or gray offspring. The gray rule asserts that a gray offspring must have at least one gray parent. Nine alleged exceptions to the chestnut rule, all involving bay offspring, and eight alleged exceptions to the gray rule, including four offspring that were also exceptions to the chestnut rule, were examined for parent-offspring genetic incompatibilities in as many as 17 genetic systems of blood-group markers. In all except one of the 17 cases it was possible to sh...
Priester WA, Glass AG, Waggoner NS.A mass survey of the distribution of congenital defects in various types of livestock was made possible by the processing by the Veterinary Medical Data Program (VMPD) of standard observations collected on 137, 717 patients seen at veterinary college clinics between Mar. 1964 and Jan. 1969. A total of 6455 animals with 1 or more congenital defects was found. The data were analysed according to species, institution and organ system. Pigs had the highest proportion of congenital defects, cats the lowest. Over all, the systems most frequently involved were the musculo-skeletal and urogenital. The...
Nikiforov TT, Rendle RB, Goelet P, Rogers YH, Kotewicz ML, Anderson S, Trainor GL, Knapp MR.A new method for typing single nucleotide polymorphisms in DNA is described. In this method, specific fragments of genomic DNA containing the polymorphic site(s) are first amplified by the polymerase chain reaction (PCR) using one regular and one phosphorothioate-modified primer. The double-stranded PCR product is rendered single-stranded by treatment with the enzyme T7 gene 6 exonuclease, and captured onto individual wells of a 96 well polystyrene plate by hybridization to an immobilized oligonucleotide primer. This primer is designed to hybridize to the single-stranded target DNA immediately...
Hauswirth R, Jude R, Haase B, Bellone RR, Archer S, Holl H, Brooks SA, Tozaki T, Penedo MC, Rieder S, Leeb T.Variants in the EDNRB, KIT, MITF, PAX3 and TRPM1 genes are known to cause white spotting phenotypes in horses, which can range from the common white markings up to completely white horses. In this study, we investigated these candidate genes in 169 horses with white spotting phenotypes not explained by the previously described variants. We identified a novel missense variant, PAX3:p.Pro32Arg, in Appaloosa horses with a splashed white phenotype in addition to their leopard complex spotting patterns. We also found three novel variants in the KIT gene. The splice site variant c.1346+1G>A occur...
Tozaki T, Ohnuma A, Kikuchi M, Ishige T, Kakoi H, Hirota KI, Kusano K, Nagata SI.Gene doping, an activity which abuses and misuses gene therapy, is a major concern in sports and horseracing industries. Effective methods capable of detecting and monitoring gene doping are urgently needed. Although several PCR-based methods that detect transgenes have been developed, many of them focus only on a single transgene. However, numerous genes associated with athletic ability may be potential gene-doping material. Here, we developed a detection method that targets multiple transgenes. We targeted 12 genes that may be associated with athletic performance and designed two TaqMan prob...
Priester WA, Glass AG, Waggoner NS.A mass survey of the distribution of congenital defects in various types of livestock was made possible by the processing by the Veterinary Medical Data Program (VMPD) of standard observations collected on 137, 717 patients seen at veterinary college clinics between Mar. 1964 and Jan. 1969. A total of 6455 animals with 1 or more congenital defects was found. The data were analysed according to species, institution and organ system. Pigs had the highest proportion of congenital defects, cats the lowest. Over all, the systems most frequently involved were the musculo-skeletal and urogenital. The...
Bellone RR.Horses perform in a variety of disciplines that are visually demanding, and any disease impacting the eye has the potential to threaten vision and thus the utility of the horse. Advances in equine genetics have enabled the understanding of some inherited ocular disorders and ocular manifestations and are enabling cross-species comparisons. Genetic testing for multiple congenital ocular anomalies, congenital stationary night blindness, equine recurrent uveitis, and squamous cell carcinoma can identify horses with or at risk for disease and thus can assist in clinical management and breeding dec...
Fontanel M, Todd E, Drabbe A, Ropka-Molik K, Stefaniuk-Szmukier M, Myćka G, Velie BD.Arabian horses are not only one of the most ancient breeds in the world, but they are also one of the most appreciated racehorse breeds today. The breed generates attention for their phenomenal endurance ability and their capability for gallop racing. Consequently, genetic testing to select the best individuals is attracting ever increasing interests from the Arabian industry. As such, the aim of this study was to further investigate associations between performance and variation at candidate genes suspected of having a key role in Arabian gallop racing performance. Generalized linear models w...
Valberg SJ, Henry ML, Herrick KL, Velez-Irizarry D, Finno CJ, Petersen JL.Genetic tests for variants in MYOT (P2; rs1138656462), FLNC (P3a; rs1139799323 or P3b; rs1142918816) and MYOZ3 (P4; rs1142544043) genes are offered commercially to diagnose myofibrillar myopathy (MFM) and type 2 polysaccharide storage myopathy (PSSM2) in Quarter Horses (QH). Objective: To determine if PSSM2-QH has histopathological features of MFM. To compare genotype and allele frequencies of variants P2, P3, P4 between control-QH and PSSM2-QH diagnosed by histopathology. Methods: Retrospective cross-sectional. Methods: The study includes a total of 229 healthy control-QH, 163 PSSM2-QH GYS1 ...
Kolb DS, Klein C.Congenital hydrocephalus has been reported for a number of horse breeds, and for Friesian horses this condition has been associated with a nonsense mutation of B3GALNT2. We report the first case of congenital hydrocephalus associated with the said mutation in a Belgian draft horse. Genetic testing and consideration of the testing results in breeding programs are warranted. Hydrocéphalie congénitale chez un cheval de trait Belge associée à une mutation non-sens de B3GALNT2. L’hydrocéphalie congénitale a été signalée pour plusieurs races de chevaux et, pour les chevaux Frisons, cette ...
Patterson Rosa L, Troop TW, Martin K, Vierra M, Foster G, Lundquist E, Brooks SA, Lafayette C.Hereditary Equine Regional Dermal Asthenia (HERDA) is an autosomal recessive condition present in the American Quarter Horse and other related breeds. Resulting from a mutation in the peptidyl-prolyl cis-trans isomerase B (PPIB) gene, HERDA is homologous to Ehlers-Danlos syndrome in humans. Characterized by fragile, hyperelastic, skin, HERDA affected horses often present first with slow-healing wounds usually on the dorsum, and resulting in atrophic scars, seromas, and ulcers. As there is no treatment for the condition affected horses are typically reported to be unrideable, and if persisten...
Finno CJ.Hoof wall separation disease (HWSD) is a genetic defect in Connemara ponies characterised by separation and cracking of the dorsal hoof wall. The disease can result in chronic inflammation, severe lameness and laminitis. Affected ponies typically show clinical signs within the first six months of life. The disease is inherited as an autosomal recessive trait. The genetic mutation is a frameshift mutation in the gene SERPINB11, (c.504_505insC). Carriers are completely normal, only ponies that are homozygous for the mutation will have clinical signs of the disease. Within the Connemara breed, ca...
Faccin M, Landsgaard KA, Milliron SM, Jennings AH, Keith Chaffin M, Giaretta PR, Rech RR.A 1.5-year-old American quarter horse gelding (case 1) and an 11-month-old American quarter horse filly (case 2) were presented for acute onset pelvic lameness and lethargy. Case 1 had nasal discharge, while case 2 developed rapid muscle atrophy. Both horses had elevated serum creatine kinase activity. The horses showed similar polyphasic histiocytic and lymphoplasmacytic myositis with necrosis, mineralization, and regeneration. Additionally, case 1 had Streptococcus equi subsp. equi-induced suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy...
Wobbe M, Reinhardt F, Reents R, Tetens J, Stock KF.Awareness of breeders of Warmblood Fragile Foal Syndrome (WFFS) increased after a widely discussed case in the USA in 2018. The hereditary connective tissue disorder, first described by a US research group in 2011 and for which a commercial genetic test exists since 2013, is caused by a point mutation in the PLOD1 gene, inherited autosomal recessively. Extension of molecular genetic testing and reporting of test results of organized horse breeders to their studbooks implies new opportunities for analyses. In Germany, data are centrally accessible through the integrated equine data base allowin...
Brown C, Stefaniuk-Szmukier M, Decloedt A, Beijerink N, Hamilton NA, Velie BD.Congenital heart defects (CHDs) can have profound and potentially life-threatening consequences on horses' health and performance capability. While CHDs are rare in the general horse population, the Arabian breed is disproportionately overrepresented and thus is widely suspected to be genetically predisposed. This review discusses the most common CHDs in Arabian horses, including ventricular septal defect (VSD), tetralogy of Fallot (TOF), patent duct arteriosus (PDA), tricuspid valve atresia (TVA) and atrial septal defect (ASD). This review also explores how future research into the genetic fa...
Cavalleri JM, Metzger J, Hellige M, Lampe V, Stuckenschneider K, Tipold A, Beineke A, Becker K, Distl O, Feige K.Cerebellar abiotrophy (CA) is a rare but significant disease in Arabian horses caused by progressive death of the Purkinje cells resulting in cerebellar ataxia characterized by a typical head tremor, jerky head movements and lack of menace response. The specific role of magnetic resonance imaging (MRI) to support clinical diagnosis has been discussed. However, as yet MR imaging has only been described in one equine CA case. The role of MR morphometry in this regard is currently unknown. Due to the hereditary nature of the disease, genetic testing can support the diagnosis of CA. Therefore, the...
McCue PM, Matthews PM, Prell MJ, Bellone RR, Allen H.Genetic testing is required for the registration of foals of most equine breeds. Objective: To describe two clinical cases of marked delayed embryonic development or delayed fertilisation in pregnancies generated by embryo transfer. Methods: Case report. Methods: Donor mares were inseminated with semen from one stallion during one oestrous cycle and semen from a different stallion on the subsequent oestrous cycle. Embryo(s) were collected 8 days after ovulation during the second oestrous cycle and transferred into synchronised recipient mares. Genetic testing was performed to determine paren...
The Journal of heredityJanuary 1, 1976
Volume 67, Issue 1 6-10 doi: 10.1093/oxfordjournals.jhered.a108667
Trommershausen-Smith A, Suzuki Y, Stormont C.The chestnut rule in equine coat-color genetics asserts that the inter se mating of chestnut horses never produces bay, black, brown or gray offspring. The gray rule asserts that a gray offspring must have at least one gray parent. Nine alleged exceptions to the chestnut rule, all involving bay offspring, and eight alleged exceptions to the gray rule, including four offspring that were also exceptions to the chestnut rule, were examined for parent-offspring genetic incompatibilities in as many as 17 genetic systems of blood-group markers. In all except one of the 17 cases it was possible to sh...
Esdaile E, Knickelbein KE, Donnelly CG, Ferneding M, Motta MJ, Story BD, Avila F, Finno CJ, Gilger BC, Sandmeyer L, Thomasy S, Bellone RR.Congenital stationary night blindness (CSNB) is an ocular disorder characterized by nyctalopia. An autosomal recessive missense mutation in glutamate metabotropic receptor 6 (GRM6 c.533C>T, p.(Thr178Met)), called CSNB2, was previously identified in one Tennessee Walking Horse and predicted to reduce binding affinity of the neurotransmitter glutamate, impacting the retinal rod ON-bipolar cell signaling pathway. Thus, the first aim was to identify the allele frequency (AF) of CSNB2 in breeds with reported cases of CSNB and breeds closely related to the Tennessee Walking Horse. The second aim ...
De Coster T, Zhao Y, Tšuiko O, Demyda-Peyrás S, Van Soom A, Vermeesch JR, Smits K.In different species, embryonic aneuploidies and genome-wide errors are a major cause of developmental failure. The increasing number of equine embryos being produced worldwide provides the opportunity to characterize and rank or select embryos based on their genetic profile prior to transfer. Here, we explored the possibility of generic, genome-wide preimplantation genetic testing concurrently for aneuploidies (PGT-A) and monogenic (PGT-M) traits and diseases in the horse, meanwhile assessing the incidence and spectrum of chromosomal and genome-wide errors in in vitro-produced equine embryos....
