Polymorphisms in canine immunoglobulin heavy chain gene cluster: a double-edged sword for diabetes mellitus in the dog.

Insulin deficiency diabetes (IDD) in dogs is an endocrine disease similar to human type 1 diabetes. There are breeds more commonly affected, such as Yorkshire Terrier and Samoyed, suggesting an underlying genetic component. However, the genetic basis for canine diabetes mellitus (DM) is not fully established. We conducted both whole-genome scans for selection signatures and GWASs to compare the genomes of 136 dogs belonging to 29 breeds previously described at low or high risk for developing DM. Candidate variants were tested in dogs with a diagnosis of IDD and controls attending the Complutense Veterinary Teaching Hospital. The only genomic region under selection (CFA8:72 700 000-74 600 000; CanFam3.1) retrieved by our analyses is included in the immunoglobulin heavy chain gene cluster, which has already been related to human human type 1 diabetes susceptibility. This region contains two non-synonymous variants, rs852072969 and rs851728071, showing significant associations with high or low risk for IDD, respectively. The first variant, rs852072969, alters a protein poorly characterised in the dog. In contrast, rs851728071 was predicted to block the synthesis of an immunoglobulin variable (V) domain in breeds at low risk for DM. Although a large and diverse V gene repertoire is thought to offer a fitness advantage, we suggest that rs851728071 prevents the formation of an auto-reactive immunoglobulin V domain probably involved in the pathophysiology of IDD and, thus, decreases the risk for the disease. These results should be interpreted with caution until the functional roles of the proposed variants have been proved in larger studies.

Aggressive behavior in cattle is associated with a polymorphism in the MAOA gene promoter.

Molecular mechanisms underlying aggressive behavior are primitive and similar among the subphylum Vertebrata. In humans, a primary goal in the study of aggression is to determine the neurobehavioral molecular factors triggering violence. Although several species have been used to study agonistic responses, researchers are limited by the difficulty of artificially inducing aggression in animals not selected for it. Conversely, the Lidia cattle breed has been selected since the eighteenth century to display agonistic responses based on traits such as aggressiveness, ferocity and mobility, all of them showing significant heritability values. This intensive selection may have driven shifts in specific allele frequencies. In a previous analysis across the autosomes, we revealed long-term selection regions including genes involved in behavioral development. In the present study, we focus on mapping recent signatures of selection associated with aggressiveness at chromosome X, by comparing Lidia cattle samples with two non-specialized Spanish breeds showing tamed behavior. The most significant markers peaked around the monoamine oxidase A (MAOA) gene, and thus the associations of three functionally important regions located near the promoter of this gene were further investigated. A polymorphism consisting of a variable number of tandem repeats of the nucleotide 'C' (BTX:105,462,494) and displaying lower number of repetitions in the Lidia breed when compared with the tamed breeds was detected. In silico analyses predicted that the g.105,462,494delsinsC variant may code for the Sp1 binding motif, one of the major transcription factors controlling the core promoter and expression of the MAOA gene in humans.

Explicit evidence for a missense mutation in exon 4 of SLC45A2 gene causing the pearl coat dilution in horses.

Four loci seem responsible for the dilution of the basic coat colours in horse: Dun (D), Silver Dapple (Z), Champagne (CH) and Cream (C). Apart from the current phenotypes ascribed to these loci, pearl has been described as yet another diluted coat colour in this species. To date, this coat colour seems to segregate only in the Iberian breeds Purebred Spanish horse and Lusitano and has also been described in breeds of Iberian origin, such as Quarter Horses and Paint Horse, where it is referred to as the 'Barlink Factor'. This phenotype segregates in an autosomal recessive manner and resembles some of the coat colours produced by the champagne CHCH and cream CCr alleles, sometimes being difficult to distinguish among them. The interaction between compound heterozygous for the pearl Cprl and cream CCr alleles makes SLC45A2 the most plausible candidate gene for the pearl phenotype in horses. Our results provide documented evidence for the missense variation in exon 4 [SLC45A2:c.985G>A; SLC45A2:p.(Ala329Thr)] as the causative mutation for the pearl coat colour. In addition, it is most likely involved as well in the cremello, perlino and smoky cream like phenotypes associated with the compound CCr and Cprl heterozygous genotypes (known as cream pearl in the Purebred Spanish horse breed). The characterization of the pearl mutation allows breeders to identify carriers of the Cprl allele and to select this specific coat colour according to personal preferences, market demands or studbook requirements as well as to verify segregation within particular pedigrees.

Detection of selection signatures for agonistic behaviour in cattle.

The identification of genomic regions including signatures of selection produced by domestication and its subsequent artificial selection processes allows the understanding of the evolution of bovine breeds. Although several studies describe the genomic variability among meat or milk production cattle breeds, there are limited studies orientated towards bovine behavioural features. This study is focused on mapping genomic signatures of selection which may provide insights of differentiation between neutral and selected polymorphisms. Their effects are studied in the Lidia cattle traditionally selected for agonistic behaviour compared with Spanish breeds showing tamed behaviour. Two different approaches, BayeScan and SelEstim, were applied using genotypic 50K SNP BeadChip data. Both procedures detected two genomic regions bearing genes previously related to behavioural traits. The frequencies of the selected allele in these two regions in Lidia breed were opposite to those found in the tamed breeds. In these genomic regions, several putative genes associated with enriched metabolic pathways related to the behavioural development were identified, as neurochondrin gene (NCDN) or glutamate ionotropic receptor kainate type subunit 3 (GRIK3) both located at BTA3 or leucine-rich repeat and Ig domain containing 2 (LINGO2) and phospholipase A2-activating protein (PLAA) at BTA8.

Genomic diversity and population structure of Mexican and Spanish bovine Lidia breed.

The Lidia bovine breed is distinguished for its low genetic exchangeability given its selection on aggressive behavior, its management uniqueness and its subdivided structure. In this study, we present a comprehensive genome-wide analysis of genetic diversity, population structure and admixture of 468 animals from Mexican and Spanish Lidia breed populations and 64 samples belonging to 10 Spanish native and American-creole breeds using 37 148 single nucleotide polymorphisms. We found similar average inbreeding values in the Lidia breed, with different distributions within groups; variability of inbreeding values among Spanish lineages was significant and no differences were found among the Mexican sub-populations. Together, the high FIS of the lineages and the behavior of the runs of homozygosity are consequences of the lineage's small effective population sizes, contributing to their inbreeding increase. Population admixture analysis discarded any influence on the genetic structure of the Lidia populations from the Spanish native and American-creole breeds. In addition, both Lidia populations depicted different genetic origins, with the exception of some Mexican individuals whose origins traced back to recent Spanish importations.

Genetic diversity of the Mexican Lidia bovine breed and its divergence from the Spanish population.

Lidia bovine breed exists since the XIV century in the Iberian Peninsula. These animals were initially produced for meat but some, showing an aggressive behaviour which difficulted their management, were used to participate in popular traditional and social events. A specialization of the breed giving rise to the original Lidia population is documented in Spain since mid-XVIII century. Following the same tradition than in the Spanish population, Mexico used aggressive animals at the beginning of the XX century until two families of breeders started importing Lidia breed bovines from Spain with the aim of specializing their production. Each family (Llaguno and González) followed different breeding managements, and currently, most of the Lidia Mexican population derives from the Llaguno line. Although genetic structure and diversity of the Spanish population have been studied (using autosomal microsatellite markers, Y chromosome DNA markers and mitochondrial DNA sequences), the Mexican population is not analysed. The aim of the study was to assess both the genetic structure and diversity of the Mexican Lidia breed and its relationship with the original Spanish population using the same molecular tools. A total of 306 animals belonging to 20 breeders issued from both existing Mexican families were genotyped, and the genetic information was compared to the previously existing Spanish information. Slightly higher levels of genetic diversity in Mexican population were found when comparing to the Spanish population, and the variability among populations accounted for differences within them showing mean values of 0.18 and 0.12, respectively. Animals from the Mexican breeders, belonging to each of the two families, clustered together, and there was little evidence of admixture with the Spanish population. The analysis of Y chromosome diversity showed a high frequency of the H6 haplotype in the Mexican population, whereas this haplotype is rare in the Spanish, which is only found in the Miura (100%) and Casta Navarra (38%) lineages. Mitochondrial DNA revealed similar haplotypic pattern in both Spanish and Mexican populations, which is in accordance with most of the Mediterranean bovine breeds. In conclusion, as the Mexican Lidia population had initially a small number of founders and its current population has been reared isolated from their Spanish ancestors since a long time, these bottleneck effects and a combination of mixed cattle origin are the factors that might erase any trace of the Spanish origin of this population.

The legacy of Columbus in American horse populations assessed by microsatellite markers.

Criollo horse populations descend from horses brought from the Iberian Peninsula over the period of colonization (15th to 17th century). They are spread throughout the Americas and have potentially undergone genetic hybridization with other breeds in the recent past. In this study, 25 autosomal microsatellites were genotyped in 50 horse breeds representing Criollo populations from 12 American countries (27 breeds), breeds from the Iberian Peninsula (19), one breed each from France and Morocco and two cosmopolitan horse breeds (Thoroughbred and Arabian). The genetic relationships among breeds identified five clusters: Celtic; Iberian; North American with Thoroughbred influence; most Colombian breeds; and nearly all other Criollo breeds. The group of "all other Criollo breeds" had the closest genetic relationship with breeds originating from the Iberian Peninsula, specifically with the Celtic group. For the whole set of Criollo breeds analysed, the estimated genetic contribution from other breeds was approximately 50%, 30% and 20% for the Celtic, Iberian and Arab-Thoroughbred groups, respectively. The spatial distribution of genetic diversity indicates that hotspots of genetic diversity are observed in populations from Colombia, Ecuador, Brazil, Paraguay and western United States, possibly indicating points of arrival and dispersion of Criollo horses in the American continent. These results indicate that Criollo breeds share a common ancestry, but that each breed has its own identity.

Candidate gene analysis of osteochondrosis in Spanish Purebred horses.

Equine osteochondrosis (OC) is a frequent developmental orthopaedic disease with high economic impact on the equine industry and may lead to premature retirement of the animal as a result of chronic pain and lameness. The genetic background of OC includes different genes affecting several locations; however, these genetic associations have been tested in only one or few populations, lacking the validation in others. The aim of this study was to identify the genetic determinants of OC in the Spanish Purebred horse breed. For that purpose, we used a candidate gene approach to study the association between loci previously implicated in the onset and development of OC in other breeds and different OC locations using radiographic data from 144 individuals belonging to the Spanish Purebred horse breed. Of the 48 polymorphisms analysed, three single nucleotide polymorphisms (SNPs) located in the FAF1, FCN3 and COL1A2 genes were found to be associated with different locations of OC lesions. These data contribute insights into the complex gene networks underlying the multifactorial disease OC, and the associated SNPs could be used in a marker-assisted selection strategy to improve horse health, welfare and competitive lifespan.

Polymorphisms in twelve candidate genes are associated with growth, muscle lipid profile and meat quality traits in eleven European cattle breeds.

Current customers' demands focus on the nutritional and sensory quality of cattle meat. Candidate gene approach allows identification of genetic polymorphisms that have a measurable effect on traits of interest. The aim of this work is to identify new molecular markers for beef production through an association study using 27 candidate genes and 314 purebred bulls from 11 European cattle breeds. Twelve genes were found associated with different lipid and meat quality traits, and among these stand out the considerable effect of CAST on fatness score, CGGBP1 on growth traits, HSPB1 on the percentage of lauric acid (12:0) and phospholipid docosahexaenoic acid (DHA 22:6 n - 3), RORA on the ratio of light absorption (K) to light scattering (S) (K/S), and TNFA on lightness (L*). Most of these traits are related to post-mortem muscle biochemical changes, which are key factors controlling meat quality and consumers' acceptance. Also, the variations produced on muscle fatty acid profiles, such as those of AANAT, CRH, CSN3, HSPB1, and TNFA, give insights into the genetic networks controlling these complex traits and the possibility of future improvement of meat nutritional quality.

Worldwide frequency distribution of the 'Gait keeper' mutation in the DMRT3 gene.

For centuries, domestic horses have represented an important means of transport and served as working and companion animals. Although their role in transportation is less important today, many horse breeds are still subject to intense selection based on their pattern of locomotion. A striking example of such a selected trait is the ability of a horse to perform additional gaits other than the common walk, trot and gallop. Those could be four-beat ambling gaits, which are particularly smooth and comfortable for the rider, or pace, used mainly in racing. Gaited horse breeds occur around the globe, suggesting that gaitedness is an old trait, selected for in many breeds. A recent study discovered that a nonsense mutation in DMRT3 has a major impact on gaitedness in horses and is present at a high frequency in gaited breeds and in horses bred for harness racing. Here, we report a study of the worldwide distribution of this mutation. We genotyped 4396 horses representing 141 horse breeds for the DMRT3 stop mutation. More than half (2749) of these horses also were genotyped for a SNP situated 32 kb upstream of the DMRT3 nonsense mutation because these two SNPs are in very strong linkage disequilibrium. We show that the DMRT3 mutation is present in 68 of the 141 genotyped horse breeds at a frequency ranging from 1% to 100%. We also show that the mutation is not limited to a geographical area, but is found worldwide. The breeds with a high frequency of the stop mutation (>50%) are either classified as gaited or bred for harness racing.

Immunohistochemical vascular factor expression in canine inflammatory mammary carcinoma.

Human inflammatory breast carcinoma (IBC) and canine inflammatory mammary carcinoma (IMC) are considered the most malignant types of breast cancer. IMC has similar characteristics to IBC; hence, IMC has been suggested as a model to study the human disease. To compare the angiogenic and angioinvasive features of IMC with non-IMC, 3 canine mammary tumor xenograft models in female SCID mice were developed: IMC, comedocarcinoma, and osteosarcoma. Histopathological and immunohistochemical characterization of both primary canine tumors and xenografts using cellular markers pancytokeratin, cytokeratin 14, vimentin, and α-smooth muscle actin and vascular factors (VEGF-A, VEGF-D, VEGFR-3, and COX-2) was performed. Tumor cell proliferation index was measured by the Ki-67 marker. The xenograft models reproduced histological features found in the primary canine tumor and preserved the original immunophenotype. IMC xenografts showed a high invasive character with tumor emboli in the dermis, edema, and occasional observations of ulceration. In addition, compared with osteosarcoma and comedocarcinoma, the IMC model showed the highest vascular factor expression associated with a high proliferation index. Likewise, IMC xenografts showed higher COX-2 expression associated with VEGF-D and VEGFR-3, as well as a higher presence of dermal lymphatic tumor emboli, suggesting COX-2 participation in IMC lymphangiogenesis. These results provide additional evidence to consider vascular factors, their receptors, and COX-2 as therapeutic targets for IBC.

Genes involved in muscle lipid composition in 15 European Bos taurus breeds.

Consumers demand healthy and palatable meat, both factors being affected by fat composition. However, red meat has relatively high concentration of saturated fatty acids and low concentration of the beneficial polyunsaturated fatty acids. To select animals prone to produce particular fat types, it is necessary to identify the genes influencing muscle lipid composition. This paper describes an association study in which a large panel of candidate genes involved in adipogenesis, lipid metabolism and energy homoeostasis was tested for effects on fat composition in 15 European cattle breeds. Sixteen genes were found to have significant effects on different lipid traits, and among these, CFL1 and MYOZ1 were found to have large effects on the ratio of 18:2/18:3, CRI1 on the amount of neutral adrenic acid (22:4 n-6), MMP1 on docosahexaenoic acid (22:6 n-3) and conjugated linoleic acid, PLTP on the ratio of n-6:n-3 and IGF2R on flavour. Several genes - ALDH2, CHRNE, CRHR2, DGAT1, IGFBP3, NEB, SOCS2, SUSP1, TCF12 and FOXO1 - also were found to be associated with both lipid and organoleptic traits although with smaller effect. The results presented here help in understanding the genetic and biochemical background underlying variations in fatty acid composition and flavour in beef.

A deletion in the bovine myostatin gene causes the double-muscled phenotype in cattle.

An exceptional muscle development commonly referred to as 'double-muscled' (Fig. 1) has been seen in several cattle breeds and has attracted considerable attention from beef producers. Double-muscled animals are characterized by an increase in muscle mass of about 20%, due to general skeletal-muscle hyperplasia-that is, an increase in the number of muscle fibers rather than in their individual diameter. Although the hereditary nature of the double-muscled condition was recognized early on, the precise mode of inheritance has remained controversial; monogenic (domainant and recessive), oligogenic and polygenic models have been proposed. In the Belgian Blue cattle breed (BBCB), segregation analysis performed both in experimental crosses and in the outbred population suggested an autosomal recessive inheritance. This was confirmed when the muscular hypertrophy (mh) locus was mapped 3.1 cM from microsatellite TGLA44 on the centromeric end of bovine chromosome 2 (ref. 5). We used a positional candidate approach to demonstrate that a mutation in bovine MSTN, which encodes myostatin, a member of the TGF beta superfamily, is responsible for the double-muscled phenotype. We report an 11-bp deletion in the coding sequence for the bioactive carboxy-terminal domain of the protein causing the muscular hypertrophy observed in Belgian Blue cattle.

Genetic characterization of Latin-American Creole cattle using microsatellite markers.

Genetic diversity in and relationships among 26 Creole cattle breeds from 10 American countries were assessed using 19 microsatellites. Heterozygosities, F-statistics estimates, genetic distances, multivariate analyses and assignment tests were performed. The levels of within-breed diversity detected in Creole cattle were considerable and higher than those previously reported for European breeds, but similar to those found in other Latin American breeds. Differences among breeds accounted for 8.4% of the total genetic variability. Most breeds clustered separately when the number of pre-defined populations was 21 (the most probable K value), with the exception of some closely related breeds that shared the same cluster and others that were admixed. Despite the high genetic diversity detected, significant inbreeding was also observed within some breeds, and heterozygote excess was detected in others. These results indicate that Creoles represent important reservoirs of cattle genetic diversity and that appropriate conservation measures should be implemented for these native breeds in order to minimize inbreeding and uncontrolled crossbreeding.

Cell adhesion molecules E-cadherin and CADM1 are differently expressed in canine inflammatory mammary cancer.

Human inflammatory breast cancer (IBC) and canine inflammatory mammary cancer (IMC) are the most aggressive and lethal types of mammary tumors with specific characteristics such as exacerbated angiogenesis, lymphangiogenesis and lymphangiotropism. E-cadherin expression is another specific feature of IBC not previously studied in canine IMC. In this study, the expression of E-cadherin and CADM1 (Cell Adhesion molecule 1) and their possible role as key molecules involved in the pathogenesis of IMC were immunohistochemically analyzed in 19 canine IMC and 15 grade III non-IMC cases. E-cadherin and CADM1 expression was higher in IMC cases (p = 0.002, p = 0.008, respectively). In the IMC group, E-cadherin cytoplasmic immunolabeling was more frequent (p = 0.035) and it was associated to the expression of the angiogenic and lymphangiogenic factors COX-2 (p = 0.009), VEGF-A (p = 0.031) and VEGF-D (p = 0.008). The differential mRNA expression between IMC and non-IMC was studied by microarray analysis in 6 cases. E-cadherin gene (CDH1) was not up-regulated in IMC cases at a transcriptional level; interestingly CADM1 was 7-fold upregulated. The differential expression of E-cadherin protein in IMC suggests a possible role of E-cadherin in the characteristic exacerbated angiogenesis and lymphangiogenesis and further support IMC as a natural model for the study of human IBC. Future studies in IBC and IMC including a broad panel of adhesion molecules are necessary to elucidate their role in the metastatic process and angiogenesis.

Y chromosome genetic diversity in the Lidia bovine breed: a highly fragmented population.

To assess the paternal gene pool in the Lidia bovine breed (or fighting bull), a total of 603 animals belonging to 81 herds classified in 33 lineages were genotyped for six Y chromosome microsatellites, one single nucleotide polymorphism and one indel. A total of 10 haplotypes were determined with a high level of frequency variation between them, ranging from 0.2 to 74%. All the haplotypes identified belong to two previously defined major haplogroups (Y1 and Y2). Two major paternal influences were identified, corresponding to the two most common haplotypes (H1Y1 and H3Y2) with frequencies of 74 and 18%, respectively. The detection of the INRA189-104 allele evidenced an African influence in the Lidia bovine breed. Low levels of haplotype diversity have been achieved and only eight lineages showed more than one haplotype. Analysis of molecular variance showed a high level of interlineage variance (F(ST) = 86%). Network results evidenced two main clusters made for those haplotypes belonging to Y1 and Y2 haplogroups, respectively. The findings support a high level of genetic structure together with a low level of genetic diversity in the Lidia bovine breed.

Relationships between Podolic cattle breeds assessed by single nucleotide polymorphisms (SNPs) genotyping.

Italian Maremmana, Turkish Grey and Hungarian Grey breeds belong to the same Podolic group of cattle, have a similar conformation and recently experienced a similar demographic reduction. The aim of this study was to assess the relationship among the analysed Podolic breeds and to verify whether their genetic state reflects their history. To do so, approximately 100 single nucleotide polymorphisms (SNPs) were genotyped on individuals belonging to these breeds and compared to genotypes of individuals of two Italian beef breeds, Marchigiana and Piemontese, which underwent different selection and migration histories. Population genetic parameters such as allelic frequencies and heterozygosity values were assessed, genetic distances calculated and assignment test performed to evaluate the possibility of recent admixture between the populations. The data show that the physical similarity among the Podolic breeds examined, and particularly between Hungarian Grey and Maremmana cattle that experienced admixture in the recent past, is mainly morphological. The assignment of individuals from genotype data was achieved using Bayesian inference, confirming that the set of chosen SNPs is able to distinguish among the breeds and that the breeds are genetically distinct. Individuals of Turkish Grey breed were clearly assigned to their breed of origin for all clustering alternatives, showing that this breed can be differentiated from the others on the basis of the allelic frequencies. Remarkably, in the Turkish Grey there were differences observed between the population of Enez district, where in situ conservation studies are practised, and that of Bandirma district of Balikesir, where ex situ conservation studies are practised out of the original raising area. In conclusion, this study demonstrates that molecular data could be used to reveal an unbiased view of past events and provide the basis for a rational exploitation of livestock, suggesting appropriate cross-breeding plans based on genetic distance or breeding strategies that include the population structure.

Assessing SNP markers for assigning individuals to cattle populations.

The effectiveness of single nucleotide polymorphisms (SNPs) for the assignment of cattle to their source breeds was investigated by analysing a panel of 90 SNPs assayed on 24 European breeds. Breed assignment was performed by comparing the Bayesian and frequentist methods implemented in the STRUCTURE 2.2 and GENECLASS 2 software programs. The use of SNPs for the reallocation of known individuals to their breeds of origin and the assignment of unknown individuals was tested. In the reallocation tests, the methods implemented in STRUCTURE 2.2 performed better than those in GENECLASS 2, with 96% vs. 85% correct assignments respectively. In contrast, the methods implemented in GENECLASS 2 showed a greater correct assignment rate in allocating animals treated as unknowns to a reference dataset (62% vs. 51% and 80% vs. 65% in field tests 1 and 2 respectively). These results demonstrate that SNPs are suitable for the assignment of individuals to reference breeds. The results also indicate that STRUCTURE 2.2 and GENECLASS 2 can be complementary tools to assess breed integrity and assignment. Our findings also stress the importance of a high-quality reference dataset in allocation studies.

Discovery, characterization and validation of single nucleotide polymorphisms within 206 bovine genes that may be considered as candidate genes for beef production and quality.

A large number of putative single nucleotide polymorphisms (SNPs) have been identified from the bovine genome-sequencing project. However, few of these have been validated and many will turn out to be sequencing artefacts or have low minor allele frequencies. In addition, there is little information available on SNPs within coding regions, which are likely to be responsible for phenotypic variation. Therefore, additional SNP discovery is necessary to identify and validate polymorphisms both in specific genes and genome-wide. Sequence-tagged sites within 286 genes were resequenced from a panel of animals representing a wide range of European cattle breeds. For 80 genes, no polymorphisms were identified, and 672 putative SNPs were identified within 206 genes. Fifteen European cattle breeds (436 individuals plus available parents) were genotyped with these putative SNPs, and 389 SNPs were confirmed to have minor allele frequencies above 10%. The genes containing SNPs were localized on chromosomes by radiation hybrid mapping and on the bovine genome sequence by Blast. Flanking microsatellite loci were identified, to facilitate the alignment of the genes containing the SNPs in relation to mapped quantitative trait loci. Of the 672 putative SNPs discovered in this work, only 11 were found among the validated SNPs and 100 were found among the approximately 2.3 million putative SNPs currently in dbSNP. The genes studied in this work could be considered as candidates for traits associated with beef production and the SNPs reported will help to assess the role of the genes in the genetic control of muscle development and meat quality. The allele frequency data presented allows the general utility of the SNPs to be assessed.

Genetic differentiation in pointing dog breeds inferred from microsatellites and mitochondrial DNA sequence.

Recent studies presenting genetic analysis of dog breeds do not focus specifically on genetic relationships among pointing dog breeds, although hunting was among the first traits of interest when dogs were domesticated. This report compares histories with genetic relationships among five modern breeds of pointing dogs (English Setter, English Pointer, Epagneul Breton, Deutsch Drahthaar and German Shorthaired Pointer) collected in Spain using mitochondrial, autosomal and Y-chromosome information. We identified 236 alleles in autosomal microsatellites, four Y-chromosome haplotypes and 18 mitochondrial haplotypes. Average F(ST) values were 11.2, 14.4 and 13.1 for autosomal, Y-chromosome microsatellite markers and mtDNA sequence respectively, reflecting relatively high genetic differentiation among breeds. The high gene diversity observed in the pointing breeds (61.7-68.2) suggests contributions from genetically different individuals, but that these individuals originated from the same ancestors. The modern English Setter, thought to have arisen from the Old Spanish Pointer, was the first breed to cluster independently when using autosomal markers and seems to share a common maternal origin with the English Pointer and German Shorthaired Pointer, either via common domestic breed females in the British Isles or through the Old Spanish Pointer females taken to the British Isles in the 14th and 16th centuries. Analysis of mitochondrial DNA sequence indicates the isolation of the Epagneul Breton, which has been formally documented, and shows Deutsch Drahthaar as the result of crossing the German Shorthaired Pointer with other breeds. Our molecular data are consistent with historical documents.