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Rebecca R. Bellone - One of the best experts on this subject based on the ideXlab platform.

  • Risk factors for equine recurrent uveitis in a population of Appaloosa horses in western Canada
    Veterinary ophthalmology, 2020
    Co-Authors: Lynne S Sandmeyer, Rebecca R. Bellone, Nicole B Kingsley, Cheryl Walder, Sheila Archer, Marina L. Leis, Bianca S Bauer
    Abstract:

    Objective To characterize clinical manifestations, measure frequency, and evaluate risk factors for equine recurrent uveitis (ERU) in Appaloosa horses in western Canada. Animals 145 Appaloosa horses. Procedures Ophthalmic examinations were completed and eyes were classified as having no or mild clinical signs, or moderate, or severe damage from ERU. Clinical signs, age, sex, base coat color, and pattern were recorded. Whole blood and/or mane hair follicles were collected for DNA extraction, and all horses were tested for the leopard complex (LP) spotting pattern allele. Pedigree analysis was completed on affected and unaffected horses, and coefficients of coancestry (CC) and inbreeding (COI) were determined. Results Equine recurrent uveitis was confirmed in 20 (14%) horses. The mean age of affected horses was 12.3 years (±5.3; range 3-25). Age was a significant risk factor for ERU diagnosis (ORyear = 1.15) and classification (ORyear = 1.19). The fewspot coat pattern was significantly associated with increased risk for ERU compared to horses that were minimally patterned or true solids. The LP/LP genotype was at a significantly greater risk for ERU compared to lp/lp (OR = 19.4) and LP/lp (OR = 6.37). Classification of ERU was greater in the LP/LP genotype compared to LP/lp. Affected horses had an average CC of 0.066, and there was a significant difference in the distribution of CC for affected horses versus the control group (P = .021). One affected horse was the sire or grandsire of nine other affected. Conclusions Age, coat pattern, and genetics are major risk factors for the diagnosis and classification of ERU in the Appaloosa.

  • genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses
    Animal Genetics, 2014
    Co-Authors: Krista L. Fritz, Heather J. Kaese, Stephanie J. Valberg, Julie A. Hendrickson, Aaron Rendahl, Rebecca R. Bellone, K. M. Dynes, M. L. Wagner, M. Lucio, F. M. Cuomo
    Abstract:

    Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value <0.05): a SNP within intron 11 of the TRPM1 gene on ECA1, an ELA class I microsatellite located near the boundary of the ELA class III and class II regions and an ELA class II microsatellite located in intron 1 of the DRA gene. Association between these three genetic markers and the ERU phenotype was confirmed in a second population of 24 insidious ERU Appaloosa cases and 16 Appaloosa controls. The relative odds of being an ERU case for each allele of these three markers were estimated by fitting a logistic mixed model with each of the associated markers independently and with all three markers simultaneously. The risk model using these markers classified ~80% of ERU cases and 75% of controls in the second population as moderate or high risk, and low risk respectively. Future studies to refine the associations at ECA1 and ELA loci and identify functional variants could uncover alleles conferring susceptibility to ERU in Appaloosa horses.

  • Genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses.
    Animal genetics, 2014
    Co-Authors: Krista L. Fritz, Heather J. Kaese, Stephanie J. Valberg, Julie A. Hendrickson, Aaron Rendahl, Rebecca R. Bellone, K. M. Dynes, M. L. Wagner, M. Lucio, F. M. Cuomo
    Abstract:

    Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value

  • congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary Ophthalmology, 2012
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P << 0.0005) and CSNB status (χ2 = 11, P < 0.0005). Conclusions  The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.

  • Congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary ophthalmology, 2011
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P 

Lynne S Sandmeyer - One of the best experts on this subject based on the ideXlab platform.

  • Risk factors for equine recurrent uveitis in a population of Appaloosa horses in western Canada
    Veterinary ophthalmology, 2020
    Co-Authors: Lynne S Sandmeyer, Rebecca R. Bellone, Nicole B Kingsley, Cheryl Walder, Sheila Archer, Marina L. Leis, Bianca S Bauer
    Abstract:

    Objective To characterize clinical manifestations, measure frequency, and evaluate risk factors for equine recurrent uveitis (ERU) in Appaloosa horses in western Canada. Animals 145 Appaloosa horses. Procedures Ophthalmic examinations were completed and eyes were classified as having no or mild clinical signs, or moderate, or severe damage from ERU. Clinical signs, age, sex, base coat color, and pattern were recorded. Whole blood and/or mane hair follicles were collected for DNA extraction, and all horses were tested for the leopard complex (LP) spotting pattern allele. Pedigree analysis was completed on affected and unaffected horses, and coefficients of coancestry (CC) and inbreeding (COI) were determined. Results Equine recurrent uveitis was confirmed in 20 (14%) horses. The mean age of affected horses was 12.3 years (±5.3; range 3-25). Age was a significant risk factor for ERU diagnosis (ORyear = 1.15) and classification (ORyear = 1.19). The fewspot coat pattern was significantly associated with increased risk for ERU compared to horses that were minimally patterned or true solids. The LP/LP genotype was at a significantly greater risk for ERU compared to lp/lp (OR = 19.4) and LP/lp (OR = 6.37). Classification of ERU was greater in the LP/LP genotype compared to LP/lp. Affected horses had an average CC of 0.066, and there was a significant difference in the distribution of CC for affected horses versus the control group (P = .021). One affected horse was the sire or grandsire of nine other affected. Conclusions Age, coat pattern, and genetics are major risk factors for the diagnosis and classification of ERU in the Appaloosa.

  • Genetic investigation of equine recurrent uveitis in Appaloosa horses
    Animal genetics, 2019
    Co-Authors: H. Rockwell, Lynne S Sandmeyer, Bianca S Bauer, Sheila Archer, Maura Mack, Thomas R. Famula, A. Dwyer, Mary E. Lassaline, Samantha K. Beeson, Molly E. Mccue
    Abstract:

    Equine recurrent uveitis (ERU) is characterized by intraocular inflammation that often leads to blindness in horses. Appaloosas are more likely than any other breed to develop insidious ERU, distinguished by low-grade chronic intraocular inflammation, suggesting a genetic predisposition. Appaloosas are known for their white coat spotting patterns caused by the leopard complex spotting allele (LP) and the modifier PATN1. A marker linked to LP on ECA1 and markers near MHC on ECA20 were previously associated with increased ERU risk. This study aims to further investigate these loci and identify additional genetic risk factors. A GWAS was performed using the Illumina Equine SNP70 BeadChip in 91 horses. Additive mixed model approaches were used to correct for relatedness. Although they do not reach a strict Bonferroni genome-wide significance threshold, two SNPs on ECA1 and one SNP each on ECA12 and ECA29 were among the highest ranking SNPs and thus warranted further analysis (P = 1.20 × 10-5 , P = 5.91 × 10-6 , P = 4.91 × 10-5 , P = 6.46 × 10-5 ). In a second cohort (n = 98), only an association with the LP allele on ECA1 was replicated (P = 5.33 × 10-5 ). Modeling disease risk with LP, age and additional depigmentation factors (PATN1 genotype and extent of roaning) supports an additive role for LP and suggests an additive role for PATN1. Genotyping for LP and PATN1 may help predict ERU risk (AUC = 0.83). The functional role of LP and PATN1 in ERU development requires further investigation. Testing samples across breeds with leopard complex spotting patterns and a denser set of markers is warranted to further refine the genetic components of ERU.

  • equine recurrent uveitis in western canadian prairie provinces a retrospective study 2002 2015
    The Canadian veterinary journal = La revue veterinaire canadienne, 2017
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Cindy Feng, Bruce H Grahn
    Abstract:

    The objectives of this study were to determine the demographics of horses with equine recurrent uveitis (ERU) presenting to the Western College of Veterinary Medicine and to describe and compare the prognosis of ERU in the Appaloosa with that in other breeds. Horses diagnosed with ERU by a veterinary ophthalmologist between 2002 and 2015 were included. Eye lesions were classified as mild, moderate, or severe based on clinical manifestations. Breed, age, severity, blindness, and final outcome were evaluated. Thirty-two horses fit the inclusion criteria; 62.5% were Appaloosas. Mean age at presentation was 12.13 ± 4.6 years. Equine recurrent uveitis was bilateral in 93.6% of horses and was severe in 59.4% of eyes at presentation. Bilateral blindness was present in 59.4% of horses at last follow-up. Of 27 horses available for follow-up, 63% were euthanized due to ERU. No significant differences in age, severity, blindness, or rate of euthanasia were noted between Appaloosas and other breeds. The Appaloosa is at increased risk for ERU, which is a devastating ocular disease.

  • congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary Ophthalmology, 2012
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P << 0.0005) and CSNB status (χ2 = 11, P < 0.0005). Conclusions  The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.

  • Congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary ophthalmology, 2011
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P 

Bruce H Grahn - One of the best experts on this subject based on the ideXlab platform.

  • equine recurrent uveitis in western canadian prairie provinces a retrospective study 2002 2015
    The Canadian veterinary journal = La revue veterinaire canadienne, 2017
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Cindy Feng, Bruce H Grahn
    Abstract:

    The objectives of this study were to determine the demographics of horses with equine recurrent uveitis (ERU) presenting to the Western College of Veterinary Medicine and to describe and compare the prognosis of ERU in the Appaloosa with that in other breeds. Horses diagnosed with ERU by a veterinary ophthalmologist between 2002 and 2015 were included. Eye lesions were classified as mild, moderate, or severe based on clinical manifestations. Breed, age, severity, blindness, and final outcome were evaluated. Thirty-two horses fit the inclusion criteria; 62.5% were Appaloosas. Mean age at presentation was 12.13 ± 4.6 years. Equine recurrent uveitis was bilateral in 93.6% of horses and was severe in 59.4% of eyes at presentation. Bilateral blindness was present in 59.4% of horses at last follow-up. Of 27 horses available for follow-up, 63% were euthanized due to ERU. No significant differences in age, severity, blindness, or rate of euthanasia were noted between Appaloosas and other breeds. The Appaloosa is at increased risk for ERU, which is a devastating ocular disease.

  • congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary Ophthalmology, 2012
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P << 0.0005) and CSNB status (χ2 = 11, P < 0.0005). Conclusions  The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.

  • Congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary ophthalmology, 2011
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P 

  • differential gene expression of trpm1 the potential cause of congenital stationary night blindness and coat spotting patterns lp in the Appaloosa horse equus caballus
    Genetics, 2008
    Co-Authors: Rebecca R. Bellone, Lynne S Sandmeyer, Sheila Archer, George W. Forsyth, Samantha A Brooks, Barbara A Murphy, Ernest Bailey, Bruce H Grahn
    Abstract:

    The Appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RT–PCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) expression in the retina of homozygous Appaloosa horses was 0.05% the level found in non-Appaloosa horses (R = 0.0005). This constitutes a >1800-fold change (FC) decrease in TRPM1 gene expression in the retina (FC = −1870.637, P = 0.001) of CSNB-affected (LP/LP) horses. TRPM1 was also downregulated in LP/LP pigmented skin (R = 0.005, FC = −193.963, P = 0.001) and in LP/LP unpigmented skin (R = 0.003, FC = −288.686, P = 0.001) and was downregulated to a lesser extent in LP/lp unpigmented skin (R = 0.027, FC = −36.583, P = 0.001). TRP proteins are thought to have a role in controlling intracellular Ca2+ concentration. Decreased expression of TRPM1 in the eye and the skin may alter bipolar cell signaling as well as melanocyte function, thus causing both CSNB and LP in horses.

  • clinical and electroretinographic characteristics of congenital stationary night blindness in the Appaloosa and the association with the leopard complex
    Veterinary Ophthalmology, 2007
    Co-Authors: Lynne S Sandmeyer, Sheila Archer, Carrie B Breaux, Bruce H Grahn
    Abstract:

    Objective  To determine the prevalence of congenital stationary night blindness (CSNB) in Appaloosa horses in western Canada, investigate the association with the leopard complex of white spotting patterns, and further characterize the clinical and electroretinographic aspects of CSNB in the Appaloosa. Animals studied  Three groups of 10 Appaloosas were studied based on coat patterns suggestive of LpLp, Lplp, and lplp genotype. Procedures  Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, measurement of corneal diameter, streak retinoscopy, scotopic and photopic full-field and flicker ERGs and oscillatory potentials (OPs) were completed bilaterally. Results  All horses in the LpLp group were affected by CSNB, while none in the Lplp or lplp groups was affected. The LpLp and Lplp groups had significantly smaller vertical and horizontal corneal diameters than the lplp group had. Median refractive error was zero for all groups. Scotopic ERGs in the LpLp (CSNB-affected) group were consistent with previous descriptions. The CSNB-affected horses had significantly longer photopic a-wave implicit times, greater a-wave amplitudes, and lower b-wave amplitudes than the Lplp and lplp (normal) groups did. No differences were present in photopic flicker amplitude or implicit times. Scotopic flickers in the CSNB-affected horses were markedly reduced in amplitude and abnormal in appearance. No differences were noted in OP implicit times; however, amplitudes of some OPs were reduced in CSNB-affected horses. There were no differences in scotopic and photopic or flicker ERGs or OPs between the normal groups. Conclusions  CSNB was present in one-third of horses studied and there was a significant association between CSNB and the inheritance of two Lp alleles. ERG abnormalities support the hypothesis that CSNB is caused by a defect in neural transmission through the rod pathway involving the inner nuclear layer.

Sheila Archer - One of the best experts on this subject based on the ideXlab platform.

  • Risk factors for equine recurrent uveitis in a population of Appaloosa horses in western Canada
    Veterinary ophthalmology, 2020
    Co-Authors: Lynne S Sandmeyer, Rebecca R. Bellone, Nicole B Kingsley, Cheryl Walder, Sheila Archer, Marina L. Leis, Bianca S Bauer
    Abstract:

    Objective To characterize clinical manifestations, measure frequency, and evaluate risk factors for equine recurrent uveitis (ERU) in Appaloosa horses in western Canada. Animals 145 Appaloosa horses. Procedures Ophthalmic examinations were completed and eyes were classified as having no or mild clinical signs, or moderate, or severe damage from ERU. Clinical signs, age, sex, base coat color, and pattern were recorded. Whole blood and/or mane hair follicles were collected for DNA extraction, and all horses were tested for the leopard complex (LP) spotting pattern allele. Pedigree analysis was completed on affected and unaffected horses, and coefficients of coancestry (CC) and inbreeding (COI) were determined. Results Equine recurrent uveitis was confirmed in 20 (14%) horses. The mean age of affected horses was 12.3 years (±5.3; range 3-25). Age was a significant risk factor for ERU diagnosis (ORyear = 1.15) and classification (ORyear = 1.19). The fewspot coat pattern was significantly associated with increased risk for ERU compared to horses that were minimally patterned or true solids. The LP/LP genotype was at a significantly greater risk for ERU compared to lp/lp (OR = 19.4) and LP/lp (OR = 6.37). Classification of ERU was greater in the LP/LP genotype compared to LP/lp. Affected horses had an average CC of 0.066, and there was a significant difference in the distribution of CC for affected horses versus the control group (P = .021). One affected horse was the sire or grandsire of nine other affected. Conclusions Age, coat pattern, and genetics are major risk factors for the diagnosis and classification of ERU in the Appaloosa.

  • Genetic investigation of equine recurrent uveitis in Appaloosa horses
    Animal genetics, 2019
    Co-Authors: H. Rockwell, Lynne S Sandmeyer, Bianca S Bauer, Sheila Archer, Maura Mack, Thomas R. Famula, A. Dwyer, Mary E. Lassaline, Samantha K. Beeson, Molly E. Mccue
    Abstract:

    Equine recurrent uveitis (ERU) is characterized by intraocular inflammation that often leads to blindness in horses. Appaloosas are more likely than any other breed to develop insidious ERU, distinguished by low-grade chronic intraocular inflammation, suggesting a genetic predisposition. Appaloosas are known for their white coat spotting patterns caused by the leopard complex spotting allele (LP) and the modifier PATN1. A marker linked to LP on ECA1 and markers near MHC on ECA20 were previously associated with increased ERU risk. This study aims to further investigate these loci and identify additional genetic risk factors. A GWAS was performed using the Illumina Equine SNP70 BeadChip in 91 horses. Additive mixed model approaches were used to correct for relatedness. Although they do not reach a strict Bonferroni genome-wide significance threshold, two SNPs on ECA1 and one SNP each on ECA12 and ECA29 were among the highest ranking SNPs and thus warranted further analysis (P = 1.20 × 10-5 , P = 5.91 × 10-6 , P = 4.91 × 10-5 , P = 6.46 × 10-5 ). In a second cohort (n = 98), only an association with the LP allele on ECA1 was replicated (P = 5.33 × 10-5 ). Modeling disease risk with LP, age and additional depigmentation factors (PATN1 genotype and extent of roaning) supports an additive role for LP and suggests an additive role for PATN1. Genotyping for LP and PATN1 may help predict ERU risk (AUC = 0.83). The functional role of LP and PATN1 in ERU development requires further investigation. Testing samples across breeds with leopard complex spotting patterns and a denser set of markers is warranted to further refine the genetic components of ERU.

  • congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary Ophthalmology, 2012
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P << 0.0005) and CSNB status (χ2 = 11, P < 0.0005). Conclusions  The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.

  • Congenital stationary night blindness is associated with the leopard complex in the miniature horse
    Veterinary ophthalmology, 2011
    Co-Authors: Lynne S Sandmeyer, Bianca S Bauer, Rebecca R. Bellone, Sheila Archer, Janelle Nelson, George W. Forsyth, Bruce H Grahn
    Abstract:

    Objective  To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied  Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures  Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results  All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P 

  • differential gene expression of trpm1 the potential cause of congenital stationary night blindness and coat spotting patterns lp in the Appaloosa horse equus caballus
    Genetics, 2008
    Co-Authors: Rebecca R. Bellone, Lynne S Sandmeyer, Sheila Archer, George W. Forsyth, Samantha A Brooks, Barbara A Murphy, Ernest Bailey, Bruce H Grahn
    Abstract:

    The Appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RT–PCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) expression in the retina of homozygous Appaloosa horses was 0.05% the level found in non-Appaloosa horses (R = 0.0005). This constitutes a >1800-fold change (FC) decrease in TRPM1 gene expression in the retina (FC = −1870.637, P = 0.001) of CSNB-affected (LP/LP) horses. TRPM1 was also downregulated in LP/LP pigmented skin (R = 0.005, FC = −193.963, P = 0.001) and in LP/LP unpigmented skin (R = 0.003, FC = −288.686, P = 0.001) and was downregulated to a lesser extent in LP/lp unpigmented skin (R = 0.027, FC = −36.583, P = 0.001). TRP proteins are thought to have a role in controlling intracellular Ca2+ concentration. Decreased expression of TRPM1 in the eye and the skin may alter bipolar cell signaling as well as melanocyte function, thus causing both CSNB and LP in horses.

F. M. Cuomo - One of the best experts on this subject based on the ideXlab platform.

  • genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses
    Animal Genetics, 2014
    Co-Authors: Krista L. Fritz, Heather J. Kaese, Stephanie J. Valberg, Julie A. Hendrickson, Aaron Rendahl, Rebecca R. Bellone, K. M. Dynes, M. L. Wagner, M. Lucio, F. M. Cuomo
    Abstract:

    Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value <0.05): a SNP within intron 11 of the TRPM1 gene on ECA1, an ELA class I microsatellite located near the boundary of the ELA class III and class II regions and an ELA class II microsatellite located in intron 1 of the DRA gene. Association between these three genetic markers and the ERU phenotype was confirmed in a second population of 24 insidious ERU Appaloosa cases and 16 Appaloosa controls. The relative odds of being an ERU case for each allele of these three markers were estimated by fitting a logistic mixed model with each of the associated markers independently and with all three markers simultaneously. The risk model using these markers classified ~80% of ERU cases and 75% of controls in the second population as moderate or high risk, and low risk respectively. Future studies to refine the associations at ECA1 and ELA loci and identify functional variants could uncover alleles conferring susceptibility to ERU in Appaloosa horses.

  • Genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses.
    Animal genetics, 2014
    Co-Authors: Krista L. Fritz, Heather J. Kaese, Stephanie J. Valberg, Julie A. Hendrickson, Aaron Rendahl, Rebecca R. Bellone, K. M. Dynes, M. L. Wagner, M. Lucio, F. M. Cuomo
    Abstract:

    Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value