Determination of Sublethal Mutation Causing Lavender Foal Syndrome in Arabian Horses From Croatia

Efendić, Maša; Mačešić, Nino; Samardžija, Marko; Vojta, Aleksandar; Korabi, Nidal; Capak, Hrvoje; Sušnić, Marija Abramović; Žaja, Ivona Žura; Pećin, Marko; Babić, Nikica Prvanović

doi:10.1016/j.jevs.2017.11.014

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…Results recently obtained by Bugno-Poniewierska et al [ 13 ] confirmed the absence of LFS in the studied group of purebred Arabian horses in Poland, indicating that the lethal allele was not introduced yet in some populations. To date, reports from South Africa, Croatia, and Egypt reported the incidence of LFS carriers [ 15 , 16 , 17 ]. Therefore, the occurrence of mutated alleles in horse population from the MENA regions is not inconceivable.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Cerebellar Abiotrophy (CA), Lavender Foal Syndrome (LFS), and Severe Combined Immunodeficiency (SCID) Variants in a Cohort of Three MENA Region Horse Breeds

Ayad

Almarzook

Besseboua

et al. 2021

Genes

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Genetic disorders in horses are mostly fatal or usually cause significant economic losses for breeders and owners. Here we studied a total of 177 Arabian, Barb and Arab-Barb horses from the Middle East and North Africa (MENA) using Sanger Sequencing and PCR-ACRS (polymerase chain reaction—artificially created restriction site) approaches to examine the genetic disorders in the studied horse breeds. We identified the genetic variations related to Cerebellar Abiotrophy (CA), Severe Combined Immunodeficiency (SCID) occurrence, and the studied population was free of the mutant allele determined Lavender Foal Syndrome (LFS). Overall, presented data showed that 15 of the studied horses are carriers of two genetic disorders; the investigated horse population showed that five Arabian horses were heterozygous for the CA-associated SNP (rs397160943). The SCID-deletion TCTCA within PRKDC was detected in ten horses (nine Arabian horses and one Arab-Barb horse). This investigation shows the importance of testing these breeds for genetic disorders to avoid further spread of deleterious variants

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Section: Resultsmentioning

confidence: 99%

Investigation of Cerebellar Abiotrophy (CA), Lavender Foal Syndrome (LFS), and Severe Combined Immunodeficiency (SCID) Variants in a Cohort of Three MENA Region Horse Breeds

Ayad

Almarzook

Besseboua

et al. 2021

Genes

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“…Here, the overall frequency of LFS carriers was 16%, which was higher than the 11.7% observed in a population of 378 stallions in South Africa, 8 the US Egyptian (10.3%) and non-Egyptian Arabian horses (1.8%), 1 and Croatian population (9.62%). 9 This could be due to Arabian breeding strategies in Egypt. The LFS condition in Egypt was previously reported on an Arabian farm, where four out of eight suspected horses were harbouring the mutant variant.…”

Section: Discussionmentioning

confidence: 99%

“…In South Africa, the frequency of LFS was 11.7% during one foaling season in 2009/2010 8 . In Croatia, the percentage of LFS carriers was approximately 9.62% 9 . On the other hand, Poland 10 and Turkey 11 were free from LFS alleles.…”

Section: Introductionmentioning

confidence: 97%

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Evidence for origin of lavender foal syndrome among Egyptian Arabian horses in Egypt

Ela

Araby

Saleh

et al. 2022

Equine Veterinary Journal

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Background Lavender foal syndrome (LFS) is a fatal hereditary condition that is inherited in an autosomal recessive pattern. This detrimental mutation is more common in Arabian foals of Egyptian origin than foals from other bloodlines. Heterozygous horses are carriers of the LFS trait and appear normal, while recessive homozygous foals died shortly after birth due to serious complications. In Egypt, in 2014, an Egyptian foal died after manifestations of neurological signs and abnormal coat colour as LFS signs. Therefore, it is important to identify LFS carriers in the population of Arabian horses in Egypt and to encourage improvement of the Arabian horse industry in Egypt by constructing a breeding system based on genetic background in order to avoid mating between carriers and reduce financial losses from deaths of affected foals. Objectives To establish a PCR‐based test for detecting the MYO5A gene mutation causing LFS in the registered Arabian horse population in Egypt prior to breeding. Study design Cross sectional survey (n = 170) plus targeted sampling (n = 30). Methods A total of 200 samples were collected from an Arabian farm in Egypt and some of them were traced for LFS based on the farm records. The LFS genotypes were identified using the PCR‐RFLP technique, fragment analysis followed by sequence analysis. Results The overall mutated allele and genotype frequencies (N/L) were 0.08 and 16%, respectively. Conclusion The observed frequency of heterozygotes suggests foals affected with LFS will be produced among Arabian horses in Egypt. Therefore, screening of the entire population for this mutation should be undertaken in the breeding program.

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“…Due to the overdominance effect, the frequency of the discussed alleles can become unexpectedly high in the population. Examples have been published describing lethal alleles at a carrier frequency >10% just by drift in various livestock species ( Charlier et al, 2016 ; Efendić et al, 2018 ; Derks et al, 2019a ). Hence, an unusual high frequency of deleterious variants does not constitute an advantage in heterozygotes per se.…”

Section: Population Genetics and Management Of Alleles Under Balancing Selectionmentioning

confidence: 99%

Review: Balancing Selection for Deleterious Alleles in Livestock

Derks

Steensma

2021

Front. Genet.

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Harmful alleles can be under balancing selection due to an interplay of artificial selection for the variant in heterozygotes and purifying selection against the variant in homozygotes. These pleiotropic variants can remain at moderate to high frequency expressing an advantage for favorable traits in heterozygotes, while harmful in homozygotes. The impact on the population and selection strength depends on the consequence of the variant both in heterozygotes and homozygotes. The deleterious phenotype expressed in homozygotes can range from early lethality to a slightly lower fitness in the population. In this review, we explore a range of causative variants under balancing selection including loss-of-function variation (i.e., frameshift, stop-gained variants) and regulatory variation (affecting gene expression). We report that harmful alleles often affect orthologous genes in different species, often influencing analogous traits. The recent discoveries are mainly driven by the increasing genomic and phenotypic resources in livestock populations. However, the low frequency and sometimes subtle effects in homozygotes prevent accurate mapping of such pleiotropic variants, which requires novel strategies to discover. After discovery, the selection strategy for deleterious variants under balancing selection is under debate, as variants can contribute to the heterosis effect in crossbred animals in various livestock species, compensating for the loss in purebred animals. Nevertheless, gene-assisted selection is a useful tool to decrease the frequency of the harmful allele in the population, if desired. Together, this review marks various deleterious variants under balancing selection and describing the functional consequences at the molecular, phenotypic, and population level, providing a resource for further study.

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Determination of Sublethal Mutation Causing Lavender Foal Syndrome in Arabian Horses From Croatia

Cited by 5 publications

References 15 publications

Investigation of Cerebellar Abiotrophy (CA), Lavender Foal Syndrome (LFS), and Severe Combined Immunodeficiency (SCID) Variants in a Cohort of Three MENA Region Horse Breeds

Investigation of Cerebellar Abiotrophy (CA), Lavender Foal Syndrome (LFS), and Severe Combined Immunodeficiency (SCID) Variants in a Cohort of Three MENA Region Horse Breeds

Evidence for origin of lavender foal syndrome among Egyptian Arabian horses in Egypt

Review: Balancing Selection for Deleterious Alleles in Livestock

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