Dr. Elizabeth Esdaile and a research team from the University of California Davis Veterinary Genetics
Laboratory screened 19 unregistered Shetland ponies from one ranch for a variety of white pattern
markers.

The researchers found inexplicable coat colors in 14 of the ponies, and began looking for other
dominant white variants. They found that all 14 were heterozygous for the W13 gene. Prior to this
discovery, W13 had only been found in two Quarter Horses-Peruvian Paso crosses and one Australian
miniature horse family.

All ponies with the W13 allele had all-white coats with pink skin phenotype, no matter which other
white spotting variants were present.

The scientists also tested hair samples of 25 miniature horses and five Shetland ponies, each of which
their owners called “white.” Two of the miniature horses were heterozygous for the W13 gene. There
were no homozygous ponies; researchers say that homozygosity is most likely lethal.

The scientists noted that the Shetland ponies that had the W13 allele were not registered, and none of
the registered Shetland ponies had the allele. The team suggested that the unregistered Shetlands may
have some Miniature Horse breeding in their past.

The researchers said these results highlight the presence of the W13 allele in both Shetland ponies and
the American Miniature Horse, and the importance of testing for the variant since inheriting two copies
of the gene is most likely lethal.

Read the study here.

Read more at HorseTalk.

The post Two Copies Of White Coat Allele May Be Lethal In Ponies appeared first on Horse Racing News | Paulick Report.

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Humans affected by vitiligo have multiple genes involved in the disease – up to 322 of them. Several of these genes have been shown to be involved in malignant melanoma susceptibility in humans.

Equine research has not shown what genes cause the disorder in horses. Dr. Thomas Druml and researchers from the University of Veterinary Medicine Vienna, the University of Sydney, the Swedish University of Agricultural Sciences, the Slovak University of Agriculture, and the University of Paris-Saclay used genetic data from 152 Lipizzaners and 104 solid-colored Norikers (an Austrian draft horse) to try to identify the genes involved in the disorder.

The scientists visually inspected study horses for vitiligo and found that 33 of the Lipizzaners (21.7 percent) had the condition. Upon investigation, they found several candidate genes on four chromosomes that seemed to play a role in vitiligo development in grey horses. Four of the genes are associated with the immune system and four play a role in tumor suppression and metastasis, which is how cancer cells spread.

The researchers also found that grey horses with a particular gene mutation (STX17) are more likely to develop melanoma. Melanoma occurs in 46.1 to 50 percent of grey Lipizzaners.

The scientists concluded that a relationship exists between the depigmentation phenotype and melanoma in grey horses. They recommend more gene-specific expression and replication studies be completed on different breeds.

Read the study here.

Read more at HorseTalk.

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A team of scientists from Kyoto University assessed the tractability of 167 Thoroughbred racehorses at a training center by having their handlers fill out a questionnaire. A genetic analysis was then run on each horse, focusing on a serotonin receptor gene that was associated with anxiety-related traits in other species. 

The researchers found a significant association between one variation of the serotonin receptor gene and lower tractability (less easily managed or controlled), specifically in fillies. The team concluded that the gene might play a role in a horse's trainability and its effect may be partially dependent on the horse's gender. 

Read more at EQUUS magazine.

The post Is There An Equine Gene For Gentleness?  appeared first on Horse Racing News | Paulick Report.

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Squamous cell carcinoma is the most common cancer in horses. Drs. Margo Crausaz, Thomas Launois, Kathryn Smith-Fleming, Annette McCoy, Kelly Knickelbein and Rebecca Bellone evaluated three cases of ocular cancer with DNA testing and confirmed that each horse had two copies of the variant gene: one from each parent. The risk allele frequency was highest in Connemara ponies. With this information, the scientists recommend Connemara ponies be DNA tested for the gene to assist in breeding selection and management in an effort to limit the possibility of inheriting a copy of the gene from both sire and dam.

Because Holsteiners and Belgian Warmbloods had lower allele frequencies, the research team recommend that additional warmbloods with cancer be evaluated to determine the importance of genotyping.

Read the study here.

Read more at HorseTalk.

The post Connemara Ponies At Greater Risk For Ocular Cancer, Study Shows appeared first on Horse Racing News | Paulick Report.

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The scientists were successful in removing the myostatin gene, which inhibits skeletal muscle mass development. This gene plays a significant role in gene-based distance aptitude of racehorses. Their gene editing techniques achieved 96.2 percent efficacy.

The team noted that additional research to determine an efficient manner of editing embryos was needed before this technique could be used to improve the athletic performance of horses. The team's long-term goal is to identify alleles that give a horse a natural sporting advantage and then incorporate them to allow other horses the same characteristics. They consider this technique a precision breeding strategy as it can deliver results to only one generation.

Read the full study here.

Read more at HorseTalk.

The post The Need For Speed: Genetic Editing Can Create Faster Horses appeared first on Horse Racing News | Paulick Report.

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