Evaluation of genetic diversity and management of disease in Border Collie dogs

Abstract

Maintaining genetic diversity in dog breeds is an important consideration for the management of inherited diseases. We evaluated genetic diversity in Border Collies using molecular and genealogical methods, and examined changes to genetic diversity when carriers for Trapped Neutrophil Syndrome (TNS) and Neuronal Ceroid Lipofuscinosis (NCL) are removed from the genotyped population. Genotype data for 255 Border Collies and a pedigree database of 83,996 Border Collies were used for analysis. Molecular estimates revealed a mean multi-locus heterozygosity (MLH) of 0.311 (SD 0.027), 20.79% of the genome consisted of runs of homozygosity (ROH ) > 1 Mb, effective population size (Ne) was 84.7, and mean inbreeding (F) was 0.052 (SD 0.083). For 227 genotyped Border Collies that had available pedigree information (GenoPed), molecular and pedigree estimates of diversity were compared. A reference population (dogs born between 2005 and 2015, inclusive; N = 13,523; RefPop) and their ancestors (N = 12,478) were used to evaluate the diversity of the population that are contributing to the current generation. The reference population had a Ne of 123.5, a mean F of 0.095 (SD 0.082), 2276 founders (f), 205.5 effective founders (fe), 28 effective ancestors (fa) and 10.65 (SD 2.82) founder genomes (Ng). Removing TNS and NCL carriers from the genotyped population had a small impact on diversity measures (ROH > 1 Mb, MLH, heterozygosity), however, there was a loss of > 10% minor allele frequency for 89 SNPs around the TNS mutation (maximum loss of 12.7%), and a loss of > 5% for 5 SNPs around the NCL mutation (maximum 5.18%). A common ancestor was identified for 38 TNS-affected dogs and 64 TNS carriers, and a different common ancestor was identified for 33 NCL-affected dogs and 28 carriers, with some overlap of prominent individuals between both pedigrees. Overall, Border Collies have a high level of genetic diversity compared to other breeds.

Genome-wide run of homozygosity analysis reveals candidate genomic regions associated with environmental adaptations of Tibetan native chickens

“…The observed heterozygosity (Ho) and the expected heterozygosity (He) were estimated based on allele frequency of all eligible SNPs, SNPs with minor allele frequency (MAF) ≥0.01 and SNPs with MAF ≥ 0.05, respectively, using ‘-hardy’ option in PLINK. Multiple-locus heterozygosity (MLH) was also calculated for each bird with formula [ 51 ], where O is the number of observed homozygotes, and N is the number of non-missing autosomal SNPs. The O and N were calculated using ‘-het’ option in PLINK.…”

Principais doenças genéticas em cães da raça Border Collie: uma revisão

“…No desenvolvimento de uma raça são selecionadas características desejáveis como aparência física, aptidão e temperamento, no entanto essas dificilmente são adquiridas sem que genes iguais se encontrem, logo propiciando um aumento de doenças genéticas (Soh et al, 2021).…”

“…No entanto se o filhote possuir os dois genes recessivos, terá uma probabilidade maior de desenvolver a doença. Por isso, é de extrema importância testar todos os cães para as diversas doenças existentes antes de acasalar (Ács et al, 2020;Soh et al, 2021).…”

“…Assim, deve-se fazer a reprodução de cães livres, ou seja, que são homozigotos dominantes com cães heterozigotos ou homozigotos recessivos, principalmente se forem promissores. Não é necessário retirar bons cães da reprodução, pois pode ocorrer o aumento da consanguinidade pelo fato de não se reproduzirem cães que carregam o gene da doença e, por consequência, selecionarem cães com parentesco para adquirir as características, assim ocorrendo também o aumento da incidência de doenças genéticas (Dool, 2002;Soh et al, 2021).…”

“…Os testes genéticos não são caros e podem ser realizados no Brasil para doenças como CEA, MDR1, glaucoma e DM, com resultados em cerca de 10 dias. Por tal razão, não há motivos para adquirir um filhote que não tenha exame ou cruzar cães que não tenham realizado o estudo genético (Ács et al, 2020;Soh et al, 2021).…”