A novel missense variant in endothelin-2 (EDN2) causes a growth and respiratory lethal syndrome in bovine

The high level of fragmentation of the Spanish Lidia cattle breed, divided into lineages called ‘castas’ and into herds within lineages based on reproductive isolation, increases the risk of homozygosity and the outbreak of recessive genetic defects. Since 2004, an increasing number of calves have been identified in a Lidia herd with signs of severe growth retardation, respiratory alterations and juvenile lethality, which constitutes a novel inherited syndrome in cattle and was subsequently termed growth and respiratory lethal syndrome. We performed a genome‐wide association study on a cohort of 13 affected calves and 24 putative non‐carrier parents, mapping the disease to a wide 6 cM region on bovine chromosome 3 (p < 10⁻⁷). Whole genome re‐sequencing of three affected calves and three putative non‐carrier parents identified a novel missense variant (c.149G>A|p.Cys50Tyr) in exon 2 of the endothelin 2 (EDN2) gene. Bioinformatic analyses of p.Cys50Tyr effects predicted them to be damaging for both the structure and the function of the edn2 protein, and to create a new site of splicing that may also affect the pattern of pre‐mRNA splicing and exon definition. Sanger sequencing of this variant on the rest of the sample set confirmed the segregation pattern obtained with whole genome re‐sequencing. The identification of the causative variant and the development of a diagnostic genetic test enable the efficient design of matings to keep the effective population size as high as possible, as well as providing insights into the first EDN2‐associated hereditary disease in cattle or other species.

Genomic Characterization of a Set of Iberian Peninsula Bovine Local Breeds at Risk of Extinction: Morenas Gallegas

Simple Summary

Genetic characterization of breeds at risk of extinction is crucial in order to develop efficient conservation plans. In this study, for the first time to our knowledge, a set of bovine breeds summarized as Morenas Gallegas (Cachena, Caldelá, Frieiresa, Limiá, and Vianesa), located in the Northwest of Spain, were studied by using genomics tools. Our aim was to analyze their genetic diversity and their genetic relationships with a set of local and cosmopolitan European bovine breeds. The results evidence the specific genetic signature of the Morenas Gallegas bovine breeds. Cachena was the only breed located in the same cluster as the Spanish bovine breeds analyzed, while Caldelá, Frieiresa, Limiá, and Vianesa were clearly separated. The genetic diversity of the set of Morenas Gallegas breeds is intermediate or high, but Frieiresa breed showed the higher value of inbreeding coefficient and requires special attention in the next years. Vianesa shows two different lineages, with an evident Frieiresa component and without it. Our results are the proof of the valuable genetic reservoir that Morenas Gallegas bovine breeds is due to their uniqueness in comparison with other Spanish bovine breeds.

Abstract

A set of five local bovine breeds in danger of extinction named Cachena, Caldelá, Limiá, Frieiresa, and Vianesa and included in the group of Morenas Gallegas are located in the Autonomous Community of Galicia at the Northwest of Spain. Local authorities launched a conservation plan at the end of the 21th century in order to preserve this important genetic reservoir. However, Morenas Gallegas bovine breeds never have been analyzed with genomic tools and this information may be crucial to develop conservation plans. The aim of the study was to analyze their genetic diversity and genetic relationships with a set of local and cosmopolitan European bovine breeds using single nucleotide polymorphisms. Our results show own genetic signatures for the Morenas Gallegas breeds which form a separate cluster when compared to the Spanish breeds analyzed, with the exception of the Cachena breed. The genetic diversity levels of the Morenas Gallegas were intermediate or high, and low inbreeding coefficients can be found except for the Frieiresa breed (11%). Vianesa breed evidenced two lineages depending on the Frieiresa component influence. The Morenas Gallegas bovine breeds group represent an important Spanish bovine genetic reservoir and despite their classification within a single generic group, the five breeds show their own genetic uniqueness.