Search Results (129)

Speed is not only the primary objective of racehorse breeding but also a crucial indicator for evaluating racehorse performance. This study investigates a newly developed racehorse breed in China. Through whole-genome resequencing, we selected 60 offspring obtained from the crossbreeding of Thoroughbred horses and Xilingol horses for this study. This breed is tentatively named “Grassland-Thoroughbred”, and the samples were divided into two groups based on racing ability: 30 racehorses and 30 non-racehorses. Based on whole-genome sequencing data, the study achieved an average sequencing depth of 25.63×. The analysis revealed strong selection pressure on chromosomes (Chr) 1 and 3. Selection signals were detected using methods such as the nucleotide diversity ratio (π ratio), integrated haplotype score (iHS), fixation index (Fst), and cross-population extended haplotype homozygosity (XP-EHH). Regions ranked in the top 5% by at least three methods were designated as candidate regions. This approach detected 215 candidate genes. Additionally, the Fst method was employed to detect Indels, and the top 1% regions detected were considered candidate regions, covering 661 candidate genes. Functional enrichment analysis of the candidate genes suggests that pathways related to immune regulation, neural signal transmission, muscle contraction, and energy metabolism may significantly influence differences in performance. Among these identified genes, PPARGC1A, FOXO1, SGCD, FOXP2, PRKG1, SLC25A15, CKMT2, and TRAP1 play crucial roles in muscle function, metabolism, sensory perception, and neurobiology, indicating their key significance in shaping racehorse phenotypes. This study not only enhances understanding of the molecular mechanisms underlying racehorse speed but also provides essential theoretical and practical references for the molecular breeding of Grassland-Thoroughbreds. Full article

The core objective of racehorse breeding is to enhance the speed and endurance of the horses. The Grassland-Thoroughbred is an emerging horse breed developed in northern China in recent years, characterized by excellent speed performance, enduring stamina, and strong environmental adaptability. However, research on the genetic characteristics within this breed and the genes associated with athletic performance remains relatively limited. We conducted whole-genome resequencing of Grassland-Thoroughbred F1, F2, F3, and the crossbred population (CY) and obtained a total of 4056.23 Gb of high-quality data after quality control. The single nucleotide polymorphisms (SNPs) were primarily distributed in intergenic regions, followed by intronic regions. Principal component analysis (PCA) and STRUCTURE revealed clear distinctions among the generations, with a notable overlap between CY and F3. Using the SNP dataset, we analyzed the number and length distribution patterns of runs of homozygosity (ROHs) in the genomes of different generational groups of Grassland-Thoroughbreds. Short ROHs ranging from 0.5 to 2 Mb were the most abundant, with the following distribution: F1 (85.15%) > F2 (82.92%) > CY (78.75%) > F3 (77.51%). Medium-length ROHs (2–8 Mb) and long ROHs (>8 Mb) together exhibited a similar but opposite trend. The average length of ROHs was 1.57 Mb. The inbreeding coefficients (F_ROH) among different generational groups of Grassland-Thoroughbreds were as follows: F1 (0.0942) < F2 (0.1197) < CY (0.1435) < F3 (0.1497). Through ROH island analysis, 10 high-frequency ROH regions were identified and annotated with 120 genes. Genomic regions and candidate genes associated with athletic traits—ACAD8, OPCML, PRDX2, NTM, NDUFB7, SCL25A15, FOXO1, and SLC4A10—were identified. These genes may play important roles in regulating muscle performance, mitochondrial energy supply, and learning and memory processes in horses and are closely associated with the athletic ability of the Grassland-Thoroughbred population. This study is the first to systematically characterize the genomic diversity and inbreeding dynamics of the Grassland-Thoroughbred during the breeding process. It identifies candidate genes that may influence athletic performance, thereby providing an important molecular foundation and theoretical basis for the genetic improvement and performance-based selection of this emerging breed. Full article

Jabal Akhdar goats, native to Oman’s high-altitude Jabal Akhdar mountain range, are recognized for their high growth rate, remarkable twinning rate, and adaptability to harsh environmental conditions. This study assesses the genetic structure, inbreeding levels, effective population size (N_e), and linkage disequilibrium (LD) of Jabal Akhdar goats while identifying genomic regions under positive selection that may contribute to their environmental adaptation. The SNP genotypes from 72 Jabal Akhdar goats and two desert breeds from Egypt (153 Barki and 60 Saidi) revealed a clear genetic distinction between both groups. Within the Jabal Akhdar goats, genetic differentiation was also identified among the three sampled villages, indicating a village-specific genetic structure. The Jabal Akhdar breed exhibited a moderate level of inbreeding (F_ROH = 0.16), greater than that of the Barki and Saidi breeds. Additionally, Jabal Akhdar goats displayed greater LD and lower N_e levels compared to the Egyptian breeds. Analysis of runs of homozygosity (ROH) and extended haplotype homozygosity-based statistics (iHS and Rsb) identified 93 genomic regions exhibiting signatures of positive selection (80 from ROH, 5 from iHS, and 8 from Rsb). These regions harbor genes associated with traits essential for environmental adaptability, including hypoxia tolerance (SUCNR1, ANGPTL1, MITF, MTUS2), muscle development and function (MBNL1, ACTC1, CAPN5), fertility (GNRHR, CCNA1, SPAG1), UV radiation resistance (UVRAG, BRCA1), bone development (SOST, MEOX1), and lipid metabolism for energy utilization (DGAT2, G6PC, SUCLG2). The results of this study provide valuable insights for identifying causative variants and haplotypes underlying the Jabal Akhdar goat’s superior adaptability. These findings can guide breeders in designing conservation strategies and improving the productivity of this unique indigenous breed. Full article

Objectives: The study investigates runs of homozygosity (ROH) and heterozygosity (ROHet), and their patterns in nine sheep breeds (772 animals in total) maintained in Poland (native and conserved), corresponding to their genetic diversity, inbreeding levels, and selection signatures. Methods: Genotypes were obtained using the Illumina OvineSNP50 BeadChip and quality-filtered SNPs were used to detect ROH and ROHet segments with the detectRUNS R package, following stringent parameters for segment length, SNP density, and genotype quality. Results: Significant variation in ROH characteristics was observed across breeds. Short ROH segments were predominant in all breeds, indicating historical inbreeding events. In contrast, longer ROH segments signified recent inbreeding, particularly in Swiniarka (SW) and Polish Merino of Colored Variety (MPC). The ROH-based genomic inbreeding coefficient (F_ROH) varied across breeds, with SW exhibiting the highest levels, suggesting reduced genetic diversity. ROHet analysis revealed that Uhruska (UHR) had the highest heterozygous segments span, while Black-headed (BH) sheep exhibited the lowest ROHet extent. ROH islands identified across breeds revealed regions under selection, associated with traits such as reproductive performance, wool quality, and body condition. Genes located within these islands (e.g., U6, SPP1, ABCG2) were linked to economically significant traits including milk production, growth, and carcass quality. Conclusions: The presented results highlight the genetic adaptations shaped by selection pressures, while also providing insights into the genetic architecture of sheep breeds maintained in Poland. Full article

Objectives: Evaluate the genetic diversity and productive traits of crossbred cattle in the Caribbean region of Colombia, through analyses derived from the assessment of the genome-wide single-nucleotide polymorphism (SNP). Methods: A total of 590 individuals and 66,098 SNPs were analyzed by principal components analysis (PCA) and detection of runs of homozygosity (ROH). The population was composed of 531 heifers marked as crossbreed and a group of 59 heifers marked as purebred Gyr. Additionally, allele frequencies were calculated for commercially important traits (CSN2, CSN3, LGB, DGAT1, GH1, CAPN1_316, CAPN1_350, CAPN1_4751, CAST_282, CAST_2870, and CAST_2959). Results: Global differences in PCA were 7.35%, and principal components explained 1.94% and 5.41% of the variation. Five ROH islands were identified in crossbred animals on chromosomes 2, 5, 7, 8, and 12. The majority of observed ROH classes were shorter than 2 Mb, 54% in crossbreed cattle and 47% in Gyr cattle. Individual inbreeding was 5.2% in crossbreed and 12% in Gyr cattle. Both groups had similar allelic and genotypic frequencies for most of the evaluated commercial traits. Only a wide variation was observed in the genes related to growth hormone (GH1) and Calpastatin (CAST_2870 and CAST_22959). Crossbreed heifers had desired allele frequencies for better milk production and quality in the genes CSN2, LGB, DGAT1, and GH1, as well as in the genes CAST_2870 and CAST_2959. Conclusions: Crossbreed cattle in the Colombian Caribbean region possess high genetic diversity and desirable allele frequencies to implement breeding and intense selection programs aimed at improving production yields. Full article

Runs of homozygosity (ROHs) are continuous homozygous segments of genomes that can be used to infer the historical development of the population. ROH studies allow us to analyze the genetic structure of a population and identify signs of selection. The present study searched for ROH regions in the Faverolle chicken breed. DNA samples from modern individuals and museum Faverolle specimens were obtained and sent for whole-genome sequencing (WGS) with 30× coverage. The results were aligned to the reference genome and subjected to additional filtering. ROH segments were then analyzed using PLINK 1.9. As a result, 10 regions on GGA1, 2, 3, 4, and 13 were identified. A total of 19 genes associated with fat deposition and lipid metabolism (GBE1, CACNA2D1, STON1, PPP1R21, RPL21L1, ATP6V0E1, CREBRF, NKX2-2, COMMD1), fertility (LHCGR, GTF2A1L, SAMD5), muscle development and body weight (VGLL3, CACNA2D1, FOXN2, ERGIC1, RPL26L1), the shape and relative size of the skeleton (FAT4), and autophagy and apoptosis (BNIP1) were found. Developmental protein genes (PAX1, NKX2-2, NKX2-4, NKX2-5) formed a separate cluster. Probably, selection for the preservation of high flavor characteristics contributed to the consolidation of these ROH regions. The present research enhances our knowledge on the Faverolle breed’s genome and pinpoints their ROH segments that are also specific «selection traces». Full article

Sickle cell disease (SCD) is a group of recessive diseases caused by the β^S sickling mutation of HBB in homozygosity or in compound heterozygosity with other pathogenic HBB mutations. Patients with severe SCD typically experience painful vaso-occlusive crises and other pain-related phenomena, including acute chest syndrome, priapism, dactylitis, avascular necrosis, and splenic sequestration and infarction. High variability of pain-related phenomena per SCD genotype indicates genetic disease modifiers (GDMs) as pathology determinants and, thus, as critical to prognosis, treatment choice, and therapy development. Articles likely holding genetic information for SCD pain phenomena were identified in PubMed and SCOPUS for article quality assessment and extraction of corresponding GDMs and observations indicative of development areas in our understanding of SCD GDMs. This process led to the initial selection of 183 articles matching the search terms, which, after two-step selection, resulted in the inclusion of 100 articles for content analysis and of significant findings for GDMs from 37 articles. Published data point to gender effects and to 51 GDM SNVs, deletions, and regions, including globin genes and significant overrepresentation of gene ontology pathways related, e.g., to oxidative stress, hypoxia, and regulation of blood pressure. Analyzed articles further pointed to additional candidate GDMs affecting SCD VOC and pain phenomena and to potential confounding factors for GWAS analyses. We found that despite the critical importance of VOC and pain phenomena for SCD pathology, corresponding clinically relevant genetic insights are held back by a shortage of large-scale, systematic multi-ethnic efforts, as undertaken by the INHERENT Network. Full article

The availability of genome sequences and single-nucleotide polymorphism (SNP) chips allows us to investigate the various genomic characteristics of species by exploring genetic diversity to aid genetic selection. The SNP chip is a cost-effective genotyping platform essential for molecular breeding of livestock. In this study, we developed a liquid SNP capture chip suitable for five Hubei (China) indigenous beef cattle breeds based on whole-genome sequencing datasets. The panel consisted of 42,686 SNPs (~40 K). These SNPs were evenly distributed on each bovine chromosome, with the majority of SNPs having minor allele frequencies >0.05 and located within intergenic regions. The performance evaluation of this SNP chip panel was proceeded by genotyping 200 individuals, revealing that this panel has a high SNP call rate of 99.48%. The SNP chip panel was further used to examine the population structure of a beef cattle population with 205 individuals and demonstrated the ability to differentiate between foreign and indigenous cattle breeds. The SNP chip was also used to determine the runs of homozygosity (ROH) within a local Hubei beef cattle population of 195 individuals. We identified 2547 ROH and several genes associated with economically important traits in the study population. Our findings demonstrate that this chip not only contributes to the understanding of the genetic characteristics of local beef cattle breeds but also provides valuable genetic information for future breeding programs, thereby improving their production efficiency and economic value. Full article

Hunan Province, located in Central-South China, has a hot and humid climate, which has shaped the unique characteristics of its cattle. In this study, we analyzed the genomic diversity of 110 indigenous Hunan cattle using whole-genome sequencing and found that they have a mixed ancestry of indicine and taurine. By grouping the cattle based on their collection regions (western, central, southeastern, and southern Hunan), we used an unsupervised three-component Gaussian model to classify the runs of homozygosity (ROH) and calculated the genomic inbreeding coefficient based on runs of homozygosity (FROH) to assess inbreeding levels. The results showed that western Hunan cattle had the highest level of hybridization, while southern Hunan cattle had the lowest. Through selective sweep analysis, we identified candidate genes and pathways related to environmental adaptation and homeostasis. Notably, the SLC5A2 gene showed strong selection signals across all four regions and exhibited a distinct haplotype compared to other referenced cattle breeds. Additionally, we detected introgression from wild species into Hunan domestic cattle and analyzed their Y-chromosome haplotypes. Full article

Background: Genetic diversity in closed populations, such as pedigree dogs, is of concern for maintaining the health and vitality of the population in the face of evolving challenges. Measures of genetic diversity rely upon estimates of homozygosity without consideration of whether the homozygosity is desirable or undesirable or if heterozygosity has a functional impact. Pedigree coefficients of inbreeding have been the classical approach yet they are inadequate unless based upon the entire population. Methods: Homozygosity measures based upon pedigree analyses (n = 11,898), SNP array data (n = 244), and whole genome sequencing (n = 23) were compared in the Bearded Collie, as well as a comparison of SNP array data to a pedigree cohort (n = 5042) and a mixed-breed cohort (n = 1171). Results: Molecular measures based upon DNA are more informative on an individual’s homozygosity levels than pedigree analyses, although SNP coefficients of inbreeding overestimate the level of inbreeding based on the nature of SNP array methodology. Whole genome sequence (WGS) analyses revealed that the heterozygosity observed is generally in variants having neutral or low impact, which would indicate that the variability may not contribute substantially to functional diversity in the population. The majority of high-impact variants were observed in the shortest runs of homozygosity (ROH) reflecting ancestral breeding and domestication practices. As expected, mixed-breed dogs displayed higher measures of genomic diversity than either Bearded Collies or other pedigree dogs as a whole using the current paradigm algorithm models to calculate homozygosity. Conclusions: Using typical DNA-based measures reflect only a single individual and not the population thereby failing to account for regions of homozygosity that reflect ancestral breeding, domestication history, breed-defining regions, or regions positively selected for health traits. Incorporating measures of genetic diversity into dog breeding schemes is meritorious. However, until measures of diversity can distinguish between breed-defining homozygosity and homozygosity associated with positive health alleles, the measures to use as selection tools need refinement before their widespread implementation. Full article

The European rabbit exists in the wild and has several highly bred domesticated forms. There are well-separated wild European rabbit populations, and intensive breeding has resulted in various forms and utilizations. In this work, we aimed to carry out an extended WGS-based population genomics study on several wild European rabbit populations and selected breeds. Utilizing multiple methods, we showed that although domestic and wild populations were clearly separated, there was evidence of admixture between them in France and Hungary. The populations showed various levels of inbreeding, with one of the Hungarian subpopulations having excess runs of homozygosity. We identified numerous variants fixed in either domestic or wild animals, two of which were found to be fixed at different alleles in the two populations. Some putatively selected regions did not overlap with any known genes in the rabbit genome, suggesting some importance to these intergenic sites. The enrichment of selected regions in certain types of transcription factor binding sites suggests a possible role for these regulatory elements during domestication. In addition, the new high-coverage rabbit whole-genome sequences may provide helpful material for further population genetics analyses. Full article

Background: This study investigates the demographic, genetic, and socioeconomic impact of the 1742–1743 plague epidemic on Córdoba, a key region within the Viceroyalty of Peru. The research focuses on the epidemic’s influence along the Royal Road (Camino Real), the main route connecting Buenos Aires and Lima, addressing a historically overlooked period with a multidimensional approach. Methods: Historical records of deaths, baptisms, and marriages from the Córdoba Archbishopric Archive were analyzed using techniques from historical demography and bioanthropology. Variables such as endogamy, exogamy, average marital distance (AMD), and consanguinity coefficients were evaluated. Results: The findings reveal a significant increase in endogamy (75–82%) and a peak exogamy index of 375 during the 1740–1744 cohort. The AMD rose to 705 km during the epidemic, indicating a shift toward marriages involving individuals from more distant regions. The total consanguinity coefficient (Ft) reached 0.00056, with the non-random component (Fn) driving this increase, suggesting heightened genetic isolation. Conclusions: The 1742–1743 plague epidemic intensified genetic isolation and consanguinity, potentially increasing homozygosity and the prevalence of recessive conditions. These changes highlight the epidemic’s long-term impact on Córdoba’s genetic diversity and demographic patterns within the colonial context. Full article

Background: Lamb health is crucial for producers; however, the percentage of lambs that die before weaning is still 15–20%. One factor that can contribute to lamb deaths is congenital diseases. A novel semi-lethal disease has been identified in newborn Polypay lambs and termed dozer lamb syndrome. This study aims to determine if there is a genetic predisposition to dozer lamb syndrome. These lambs are weak and unable to lift their heads, suckle, and swallow, resulting in nasal reflux. Methods: Genetic analyses, including a genome-wide association, runs of homozygosity, and fine mapping to determine haploblock within regions of interest, were utilized in determining genetic predispositions to dozer lamb syndrome. Results: The genome-wide association study identified a region of chromosome 15 with three significant SNPs (p-values of 6.81 × 10⁻⁶, 5.71 × 10⁻⁶, and 8.52 × 10⁻⁶). Genetic analysis identified a run of homozygosity on the same region of chromosome 15 with an odds ratio of 236.7. Fine mapping of this region identified three haploblocks associated with the dozer lamb syndrome (p-value = 2.41 × 10⁻⁵). Conclusions: The most significant and promising gene in this region is CELF1, which is known to play an important role in muscle development. Abnormal CELF1 abundance and cellular location are reported to result in abnormal muscle development. Identification of genetic aberrations associated with dozer lamb syndrome provides a tool for decreasing or eliminating the genotype and, thus, the associated phenotype(s) from Polypay sheep. Full article

Background/Objectives: The failure of physiological left-right (LR) patterning, a critical embryological process responsible for establishing the asymmetric positioning of internal organs, leads to a spectrum of congenital abnormalities characterized by laterality defects, collectively known as “heterotaxy”. MMP21 biallelic variants have recently been associated with heterotaxy syndrome and congenital heart defects (CHD). However, the genotype–phenotype correlations and the underlying pathogenic mechanisms remain poorly understood. Methods: Patients harboring biallelic MMP21 missense variants who underwent diagnostic genetic testing for CHD or heterotaxy were recruited at the Institute for Maternal and Child Health—I.R.C.C.S. “Burlo Garofolo”. Additionally, a literature review on MMP21 missense variants was conducted, and clinical data from reported patients, along with molecular data from in silico and modeling tools, were collected. Results: A total of 18 MMP21 missense variants were reported in 26 patients, with the majority exhibiting CHD (94%) and variable extra-cardiac manifestations (64%). In our cohort, through Whole-Exome Sequencing (WES) analysis, the missense p.(Met301Ile) variant was identified in two unrelated patients, who both presented with heterotaxy syndrome. Conclusions: Our comprehensive analysis of MMP21 missense variants supports the pathogenic role of the p.(Met301Ile) variant and provides significant insights into the disease pathogenesis. Specifically, missense variants are distributed throughout the gene without clustering in specific regions, and phenotype comparisons between patients carrying missense variants in compound heterozygosity or homozygosity do not reveal significant differences. These findings may suggest a potential loss-of-function mechanism for MMP21 missense variants, especially those located in the catalytic domain, and highlight their critical role in the pathogenesis of heterotaxy syndrome. Full article

Background: Runs of homozygosity (ROHs) and heterozygosity (ROHets) serve for the identification of genomic regions as candidates of selection, local adaptation, and population history. Methods: The present study aimed to comprehensively explore the ROH and ROHet patterns and hotspots in Greek native dairy goats, Eghoria and Skopelos, genotyped with the Illumina Goat SNP50 BeadChip. SNP and functional enrichment analyses were conducted to further characterize hotspots and the candidate genes located within these genomic regions. Genetic relationships between and within breeds and inbreeding coefficients were also evaluated. Results: Clear genetic differentiation and diversified management practices were depicted between the two native populations. The ROH and ROHet average genome coverage for Skopelos (65.35 and 35 Mb) and Eghoria (47.64 and 43 Mb) indicated differences in mainland and insular goats, with Skopelos showing more long ROH fragments, reflecting its geographic isolation and small population size. An ROH hotspot (CHR12: 43.59–44.61 Mb) detected in the Skopelos population has been also reported across European goats and co-localizes with a selection signal detected in the Egyptian Barki goats and sheep adapted to hot–arid conditions. A novel ROH hotspot (CHR18: 60.12–61.81 Mb), shared among the Greek breeds, harbors candidate genes enriched in biosynthesis, metabolism, and immune response. Two well-conserved ROHet islands were detected in Greek goats on chromosomes 1 and 18, with genes participating in development and embryogenesis. The Eghoria population showed the highest number of ROHet islands, potentially reflecting its adaptability to diverse environments. Conclusions: These findings offer new insights into the environmental adaptation and artificial selection in Greek goats and could be utilized in future breeding strategies for sustainable goat farming. Full article