Exonisation of an intronic L1 element in the dystrophin gene associated with X-linked muscular dystrophy in a Border Collie dog.

X-linked recessive dystrophinopathies are the most common muscular dystrophies (MDs) in humans and dogs. To date, 20 breed-specific MD-associated variants are described in the canine dystrophin gene (DMD), including one associated with dystrophin-deficient MD in the Border Collie mixed breed. Here, we report the diagnosis and follow-up of mild dystrophin-deficient MD in a 5-month-old male Border Collie, associated with a novel DMD variant. Diagnosis was based on neurological examination and laboratory evaluations including creatine kinase activity, electromyography and muscle biopsies with immunofluorescent staining. Inspection of the Sashimi plots of the RNA-seq data from the affected muscle biopsy led to the discovery of a 162-bp L1 pseudoexon in DMD intron 63, introducing a frameshift and a premature stop codon (NM_001003343.1: c.9271_9272insN[162] p.(Ala3091fs*21)). Reduced DMD mRNA levels were detected for both the non-pseudoexon (50× less) and pseudoexon (3× less) containing transcripts in the affected muscle, compared with the level of the non-pseudoexon containing transcript in a control muscle, resulting in very low dystrophin protein levels and the upregulation of utrophin. Because the variant was only found in the affected dog, not in the healthy mother and grandmother, or in 108 unrelated Border Collies from the Belgian population (46 males and 62 females), it was considered a de novo variant. Although the prognosis for dystrophinopathy is generally regarded as poor, the dog stabilised at the age of 6 months and is still clinically stable at the age of 2 years.

The c.126C>A(p.(Cys42Ter)) SLC7A10 nonsense variant is a candidate causative variant for paradoxical pseudomyotonia in English Cocker and Springer Spaniels.

Paradoxical pseudomyotonia has previously been described in the English Cocker Spaniel (ECS) and English Springer Spaniel (ESS) breeds, without the identification of potentially causative variants. This disease is characterised by episodes of exercise-induced generalised myotonic-like muscle stiffness, phenotypically similar to congenital pseudomyotonia in cattle, and paramyotonia congenita and Brody disease in people. Four additional affected ESS dogs with paradoxical pseudomyotonia are described in this report, together with the identification of the autosomal recessive c.126C>A(p.(Cys42Ter)) SLC7A10 nonsense variant as candidate disease-causing variant in both ECS and ESS. The variant has an estimated prevalence of 2.5% in both breeds in the British study samples, but was not identified in the Belgian study samples. Genetic testing-based breeding should be a useful tool to eliminate this disease in the future, although an effective treatment option is available for severely affected dogs.

qPCR assays with dual-labeled probes for genotyping honey bee variants associated with varroa resistance.

BACKGROUND: The varroa mite is one of the main causes of honey bee mortality. An important mechanism by which honey bees increase their resistance against this mite is the expression of suppressed mite reproduction. This trait describes the physiological inability of mites to produce viable offspring and was found associated with eight genomic variants in previous research. RESULTS: This paper presents the development and validation of high-throughput qPCR assays with dual-labeled probes for discriminating these eight single-nucleotide variants. Amplicon sequences used for assay validation revealed additional variants in the primer/probe binding sites in four out of the eight assays. As for two of these the additional variants interfered with the genotyping outcome supplementary primers and/or probes were developed. Inclusion of these primers and probes in the assay mixes allowed for the correct genotyping of all eight variants of interest within our bee population. CONCLUSION: These outcomes underline the importance of checking for interfering variants in designing qPCR assays. Ultimately, the availability of this assay allows genotyping for the suppressed mite reproduction trait and paves the way for marker assisted selection in breeding programs.

Antibiotic affects the gut microbiota composition and expression of genes related to lipid metabolism and myofiber types in skeletal muscle of piglets.

BACKGROUND: Early-life antibiotic administration is known to affect gut microbiota and host adiposity, but the effects of antibiotic exposure on skeletal muscle properties remain unknown. The present study evaluated the changes in skeletal muscle properties including myofiber characteristics and composition, as well as intramuscular fat (IMF) content in skeletal muscle of piglets when exposed to a tylosin-containing diet. RESULTS: A total of 18 piglets (28 days of age) were randomly allocated into two groups: control basal diet (Control) and Control + 100 mg tylosin phosphate/kg of feed (Antibiotic). The trial lasted for 39 days. High-throughput amplicon sequencing revealed that no significant difference in initial gut microbiota composition was existed between Control and Antibiotic groups. Antibiotic administration increased body weight and growth rate and decreased feed to gain ratio of pigs (P < 0.05). The carcass lean and fat volumes of pigs were increased by the tylosin administration (P < 0.05). Antibiotic treatment increased myofiber density and the expression of genes related to type I and type IIb myofibers in longissimus muscle (P < 0.05). The IMF content in longissimus muscle was increased by antibiotic exposure (P < 0.05). Antibiotic administration increased expression of genes related to fatty acid uptake and de novo synthesis, and decreased expression of genes related to triglyceride hydrolysis (P < 0.05). Tylosin administration affected taxonomic distribution and beta diversity of the caecal and colonic microbiota of piglets. CONCLUSION: These results confirm that the growth performance, myofiber composition and muscle lipid metabolism are affected by antibiotic administration, which may be associated with an altered gut microbiota, suggesting that the gut microbiota could be served as a potential target for modulating skeletal muscle properties of host.

Methylation of selected CpG islands involved in the transcription of myeloperoxidase and superoxide dismutase 2 in neutrophils of periparturient and mid-lactation cows.

It is generally accepted that intracellular killing of microorganisms by production of reactive oxygen species (ROS) in the phagosome of the neutrophil is an important arm of innate defense. High-producing dairy cows are prone to periparturient metabolic and infectious diseases. Both myeloperoxidase (MPO) activity and ROS production decrease the day of parturition. Several studies have demonstrated changes in the expression of genes involved in, for example, metabolism and defense in the circulating neutrophil during peripartum. In this study, we wanted to further characterize the periparturient neutrophil in terms of its oxidative killing capacity by analyzing the oxidative burst at 3 levels. First, the ROS phenotype was evaluated using chemiluminescence. The cows (sampled within 24 h after parturition and at 135 d in milk) showed a significantly slower production of ROS at parturition. Both primiparous (n = 13) and multiparous (n = 12) cows were included in this study, but parity did not affect the kinetics of ROS production. Second, the expression of 11 genes involved in ROS production was measured in the same cows: cytochrome b-245 α and ß chain (CYBA, CYBB; coding for membrane-bound constituents of NADPH oxidase); neutrophil cytosolic factors 1, 2, and 4 (NCF1, NCF2, and NCF4); Rac family small GTPase 1 and 2 (RAC1 and RAC2; coding for regulatory proteins of NADPH oxidase); superoxide dismutase 2 (SOD2); catalase (CAT); myeloperoxidase (MPO; coding for enzymes involved in metabolizing downstream ROS); and spleen-associated tyrosine kinase (SYK; involved in signaling). During peripartum, a shift in expression in the oxidative killing pathway was observed, characterized by a downregulation of MPO and a simultaneous upregulation of the genes coding for NADPH oxidase. Third, as total DNA methylation is known to change during pregnancy, we investigated whether the observed differences were due to different methylation patterns. Promotor regions initiate transcription of particular genes; therefore, we analyzed the methylation status in annotated CpG islands of MPO and SOD2, 2 genes with a significant difference in expression between both lactation stages. The differences in methylation of these CpG islands were nonsignificant. High-throughput techniques may be necessary to obtain more detailed information on the total DNA methylation dynamics in bovine neutrophils and increase our understanding of how gene expression is controlled in neutrophils.

Blocking connexin channels improves embryo development of vitrified bovine blastocysts.

Connexins (Cxs) are required for normal embryo development and implantation. They form gap junctions (GJs) connecting the cytoplasm of adjacent cells and hemichannels (HCs), which are normally closed but open in response to stress conditions. Excessive HC opening is detrimental for cell function and may lead to cell death. We found that hatching of in vitro-produced bovine embryos, matured in serum-containing conditions, was significantly improved when vitrification/warming was done in the presence of Gap26 that targets GJA1 (Cx43) and GJA4 (Cx37). Further work showed that HCs from blastocysts produced after oocyte maturation in the presence of serum were open shortly after vitrification/warming, and this was prevented by Gap26. Gap26, applied for the exposure times used, inhibited Cx43 and Cx37 HCs while it did not have an effect on GJs. Interestingly, Gap26 had no effect on blastocyst degeneration or cell death. We conclude that blocking HCs protects embryos during vitrification and warming by a functional effect not linked to cell death.

Intrauterine growth restriction in neonatal piglets affects small intestinal mucosal permeability and mRNA expression of redox-sensitive genes.

Neonates with intrauterine growth restriction (IUGR) show lower efficiency of nutrient utilization compared to normal birth weight (NBW) newborns. This study was conducted using neonatal piglets as a model to test the hypothesis that IUGR affects the intestinal barrier function, intestinal structure, and antioxidant system development during the suckling period. The small intestinal mucosae were obtained from IUGR and NBW littermates in the suckling period (d 0, 3, 8, and 19 postnatal). The epithelial barrier function was assessed by FITC-dextran 4 (FD4) and horseradish peroxidase (HRP) fluxes across the epithelium, histomorphologic measurements, and expression of tight-junction proteins. Redox status represented by the glutathione disulfide/glutathione ratio and malondialdehyde concentrations was determined, whereas mRNA expressions of some redox-sensitive proteins were quantified. Results showed that IUGR piglets exhibited a 2-fold higher intestinal permeability in the proximal small intestine on d 0 (P < 0.05), and this difference between IUGR and NBW piglets was widened to 3 and 4 times for FD4 and HRP, respectively (P < 0.05), on d 3. In accordance, expression of occludin was down-regulated at the transcriptional level in IUGR piglets at d 0 and 19 (P < 0.01). Furthermore, the transcription of heme oxygenase 1, catalase, and thioredoxin reductase genes was down-regulated in IUGR piglets, mainly on postnatal d 0 and 19 (P < 0.01). It appears that IUGR subjects have a lower capacity to mount an antioxidant response in the early postnatal period. Collectively, these results add to our understanding of the mechanisms responsible for intestinal dysfunction in IUGR neonates.

Suboptimal culture conditions induce more deviations in gene expression in male than female bovine blastocysts.

BACKGROUND: Since the development of in vitro embryo production in cattle, different supplements have been added to culture media to support embryo development, with serum being the most popular. However, the addition of serum during embryo culture can induce high birthweights and low viability in calves (Large Offspring Syndrome). Analysis of global gene expression in bovine embryos produced under different conditions can provide valuable information to optimize culture media for in vitro embryo production. RESULTS: We used RNA sequencing to examine the effect of in vitro embryo production, in either serum-containing or serum-free media, on the global gene expression pattern of individual bovine blastocysts. Compared to in vivo derived embryos, embryos produced in serum-containing medium had five times more differentially expressed genes than embryos produced in serum-free conditions (1109 vs. 207). Importantly, in vitro production in the presence of serum appeared to have a different impact on the embryos according to their sex, with male embryos having three times more genes differentially expressed than their female counterparts (1283 vs. 456). On the contrary, male and female embryos produced in serum-free conditions showed the same number (191 vs. 192) of genes expressed differentially; however, only 44 of those genes were common in both comparisons. The pathways affected by in vitro production differed depending on the type of supplementation. For example, embryos produced in serum-containing conditions had a lower expression of genes related to metabolism while embryos produced in serum-free conditions showed aberrations in genes involved in lipid metabolism. CONCLUSIONS: Serum supplementation had a major impact on the gene expression pattern of embryos, with male embryos being the most affected. The transcriptome of embryos produced in serum-free conditions showed a greater resemblance to that of in vivo derived embryos, although genes involved in lipid metabolism were altered. Male embryos appeared to be most affected by suboptimal in vitro culture, i.e. in the presence of serum.

The Equine Embryo Influences Immune-Related Gene Expression in the Oviduct.

Although the equine oviduct clearly affects early embryo development and the selective transport of equine embryos through the oviduct indicates a reciprocal interaction, the influence of the embryo on gene expression in the oviduct remains to be determined in the horse. The aim of this study was to examine this by means of RNA sequencing. Four days after ovulation, epithelial cells ipsilateral and contralateral to the ovulation side from five cyclic and five pregnant mares were collected from the oviduct. RNA was extracted, samples were sequenced, and data analysis was performed to determine differentially expressed genes (DEGs) (P value ≤0.05 and absolute fold change ≥2) and to provide functional interpretation. A total of 10 743 transcripts were identified and 253 genes were found to be upregulated and 108 to be downregulated in the pregnant ipsilateral oviduct when compared to the cyclic ipsilateral oviduct. Comparison of the ipsilateral and the contralateral oviduct indicated 164 DEGs in pregnant mares and 77 DEGs in cyclic mares. Enriched functional categories were detected only in the comparison of pregnant and cyclic ipsilateral oviducts and showed that the equine embryo affects the expression of immune response-related genes in the oviduct, with marked upregulation of interferon-associated genes. This research represents the foundation for further assessment of the role of specific genes in the early embryo-maternal dialogue of the horse.

High oxygen tension increases global methylation in bovine 4-cell embryos and blastocysts but does not affect general retrotransposon expression.

Retrotransposons are transposable elements that insert extra copies of themselves throughout the genome via an RNA intermediate using a 'copy and paste' mechanism. They account for more than 44% of the bovine genome and have been reported to be functional, especially during preimplantation embryo development. In the present study, we tested whether high oxygen tension (20% O2) influences global DNA methylation analysed by immunofluorescence staining of developing bovine embryos and whether this has an effect on the expression of some selected retrotransposon families. High oxygen tension significantly increased global DNA methylation in 4-cell embryos and blastocysts. A significant expression difference was observed for ERV1-1-I_BT in female blastocysts, but no significant changes were observed for the other retrotransposon families tested. Therefore, the study indicates that global DNA methylation is not necessarily correlated with retrotransposon expression in bovine preimplantation embryos.

Differential expression of CXCR1 and commonly used reference genes in bovine milk somatic cells following experimental intramammary challenge.

BACKGROUND: Chemokine (C-X-C motif) receptor 1 (CXCR1 or IL-8RA) plays an important role in the bovine mammary gland immunity. Previous research indicated polymorphism c.980A > G in the CXCR1 gene to influence milk neutrophils and mastitis resistance. In the present study, four c.980AG heifers and four c.980GG heifers were experimentally infected with Staphylococcus chromogenes. RNA was isolated from milk somatic cells one hour before and 12 hours after the experimental intramammary challenge. Expression of CXCR1 and eight candidate reference genes (ACTB, B2M, H2A, HPRT1, RPS15A, SDHA, UBC and YWHAZ) was measured by reverse transcription quantitative real-time PCR (RT-qPCR). Differences in relative CXCR1 expression between c.980AG heifers and c.980GG heifers were studied and the effect of the experimental intramammary challenge on relative expression of CXCR1 and the candidate reference genes was analyzed. RESULTS: Relative expression of CXCR1 was not associated with polymorphism c.980A > G but was significantly upregulated following the experimental intramammary challenge. Additionally, differential expression was detected for B2M, H2A, HPRT1, SDHA and YWHAZ. CONCLUSIONS: This study reinforces the importance of CXCR1 in mammary gland immunity and demonstrates the potential effect of experimental intramammary challenge on expression of candidate reference genes in milk somatic cells.

Maternal immunity enhances systemic recall immune responses upon oral immunization of piglets with F4 fimbriae.

F4 enterotoxigenic Escherichia coli (ETEC) cause diarrhoea and mortality in piglets leading to severe economic losses. Oral immunization of piglets with F4 fimbriae induces a protective intestinal immune response evidenced by an F4-specific serum and intestinal IgA response. However, successful oral immunization of pigs with F4 fimbriae in the presence of maternal immunity has not been demonstrated yet. In the present study we aimed to evaluate the effect of maternal immunity on the induction of a systemic immune response upon oral immunization of piglets. Whereas F4-specific IgG and IgA could be induced by oral immunization of pigs without maternal antibodies and by intramuscular immunization of pigs with maternal antibodies, no such response was seen in the orally immunized animals with maternal antibodies. Since maternal antibodies can mask an antibody response, we also looked by ELIspot assays for circulating F4-specific antibody secreting cells (ASCs). Enumerating the F4-specific ASCs within the circulating peripheral blood mononuclear cells, and the number of F4-specific IgA ASCs within the circulating IgA(+) B-cells revealed an F4-specific immune response in the orally immunized animals with maternal antibodies. Interestingly, results suggest a more robust IgA booster response by oral immunization of pigs with than without maternal antibodies. These results demonstrate that oral immunization of piglets with F4-specific maternal antibodies is feasible and that these maternal antibodies seem to enhance the secondary systemic immune response. Furthermore, our ELIspot assay on enriched IgA(+) B-cells could be used as a screening procedure to optimize mucosal immunization protocols in pigs with maternal immunity.

Porcine EEF1A1 and EEF1A2 genes: genomic structure, polymorphism, mapping and expression.

Eukaryotic translation elongation factor 1 alpha (EEF1A) plays a key role in protein synthesis. In higher vertebrates EEF1A occurs in two isoforms, EEF1A1 and EEF1A2, encoded by distinct genes. The purpose of this study was to compare the two porcine genes as for the genomic sequence, gene organization and mRNA expression in different tissues, as well as to search for polymorphism and chromosomal assignment. Standard methods of DNA and mRNA analysis were used. We determined the complete genomic sequence of the porcine EEF1A1 and EEF1A2 genes. The two genes differ in the lengths of transcription units (3102 and 8588 bp, respectively), but have similar genomic organization and their coding sequences are highly similar (78% identity of coding sequences and 92.4% identity of amino acid sequences). Several polymorphisms in the two genes were detected. EEF1A1 and EEF1A2 were mapped to SSC1p11.1 and SSC17q23.3, respectively. mRNA of EEF1A1 was expressed in all studied tissues (the highest expression was in 44-day fetal muscle and low expression in adult liver and brain), while EEF1A2 was expressed only in skeletal-muscle, tongue, heart, diaphragm and brain tissues. EEF1A2 was not expressed in fetal muscle tissue (44 days). In this paper results are provided on genomic sequences, genomic organization, polymorphism, chromosomal assignment and spatial and temporal expressions of the porcine EEF1A1 and EEF1A2 genes. Novel polymorphisms were described in both genes. Porcine EEF1A2 was studied for the first time.

Optimisation of the bovine whole in vitro embryo system as a sentinel for toxicity screening: a cadmium challenge.

Developmental toxicity testing could greatly benefit from the availability of an in vitro alternative model based on the use of animal embryos that have better human-like physiology than the currently-used alternative models. These current models are insufficient, as extrapolation of the results can be challenging. Therefore, an in vitro bovine embryo culture system was used to expose individual morulae to test substances, and to study developmental characteristics up to the blastocyst stage. Cadmium was chosen as the reference toxicant to investigate the sensitivity of the bovine morulae to various concentrations and exposure times. Oocytes from slaughterhouse-obtained bovine ovaries, were maturated, fertilised and cultured up until the morula stage. Morulae were exposed to different cadmium concentrations for 18 or 70 hours, and developmental competence, embryo quality and the expression of cadmium exposure-related genes were evaluated. Cadmium exposure hampered embryonic developmental competence and quality. Compared with the 18-hour exposure, the 70-hour exposure induced a 20-fold higher toxic response with regard to developmental competence and a more 'cadmium-typical' transcript expression. The bovine morula might be a promising tool for toxicity testing as, following exposure, the embryos reacted in a sensitive and 'cadmium-typical' manner to our reference toxicant.

Variation in 12 porcine genes involved in the carbohydrate moiety assembly of glycosphingolipids does not account for differential binding of F4 Escherichia coli and their fimbriae.

BACKGROUND: Glycosphingolipids (GSLs) are important membrane components composed of a carbohydrate structure attached to a hydrophobic ceramide. They can serve as specific membrane receptors for microbes and microbial products, such as F4 Escherichia coli (F4 ETEC) and isolated F4 fimbriae. The aim of this study was to investigate the hypothesis that variation in genes involved in the assembly of the F4 binding carbohydrate moiety of GSLs (i.e. ARSA, B4GALT6, GAL3ST1, GALC, GBA, GLA, GLB1, GLB1L, NEU1, NEU2, UGCG, UGT8) could account for differential binding of F4 ETEC and their fimbriae. RESULTS: RT-PCR could not reveal any differential expression of the 12 genes in the jejunum of F4 receptor-positive (F4R(+)) and F4 receptor-negative (F4R(-)) pigs. Sequencing the complete open reading frame of the 11 expressed genes (NEU2 was not expressed) identified 72 mutations. Although some of them might have a structural effect, none of them could be associated with a F4R phenotype. CONCLUSION: We conclude that no regulatory or structural variation in any of the investigated genes is responsible for the genetic susceptibility of pigs towards F4 ETEC.

Associations between CXCR1 polymorphisms and pathogen-specific incidence rate of clinical mastitis, test-day somatic cell count, and test-day milk yield.

The CXCR1 gene plays an important role in the innate immunity of the bovine mammary gland. Associations between single nucleotide polymorphisms (SNP) CXCR1c.735C>G and c.980A>G and udder health have been identified before in small populations. A fluorescent multiprobe PCR assay was designed specifically and validated to genotype both SNP simultaneously in a reliable and cost-effective manner. In total, 3,106 cows from 50 commercial Flemish dairy herds were genotyped using this assay. Associations between genotype and detailed phenotypic data, including pathogen-specific incidence rate of clinical mastitis (IRCM), test-day somatic cell count, and test-day milk yield (MY) were analyzed. Staphylococcus aureus IRCM tended to associate with SNP c.735C>G. Cows with genotype c.735GG had lower Staph. aureus IRCM compared with cows with genotype c.735CC (rate ratio = 0.35, 95% confidence interval = 0.14­0.90). Additionally, a parity-specific association between Staph. aureus IRCM and SNP c.980A>G was detected. Heifers with genotype c.980GG had a lower Staph. aureus IRCM compared with heifers with genotype c.980AG (rate ratio = 0.15, 95% confidence interval = 0.04­0.56). Differences were less pronounced in multiparous cows. Associations between CXCR1 genotype and somatic cell count were not detected. However, MY was associated with SNP c.735C>G. Cows with genotype c.735GG out-produced cows with genotype c.735CC by 0.8 kg of milk/d. Results provide a basis for further research on the relation between CXCR1 polymorphism and pathogen-specific mastitis resistance and MY.

Identification of a microscopically selected microorganism in milk samples.

Identification of unwanted microbial contaminants microscopically observed in food products is challenging due to their low abundance in a complex matrix, quite often containing other microorganisms. Therefore, a selective identification method was developed using laser capture microdissection in combination with direct-captured cell PCR. This procedure was validated with Geobacillus stearothermophilus and further used to identify microbial contaminants present in some industrial milk samples. The microscopically observed contaminants were identified as mainly Methylobacterium species.

Evaluation of enzymatic protocols to optimize efficiency of bovine adipose tissue-derived mesenchymal stromal cell isolation.

Sustainable food provision for a continuously growing human population is one of the major challenges for the next decades. Cultured meat represents one of the alternatives which is currently extensively explored. Yet, the most appropriate cell type, capable of long-term proliferation and myogenic differentiation, remains to be identified. Bovine mesenchymal stromal cells (MSCs) are considered as a promising cell source. Within the context of cultured meat production, it is mandatory to maximize cell yield per tissue source. Although many enzymatic methods to isolate MSCs from adipose tissue (AT) have been described, cell yield has never been compared. In this study, we evaluate 32 isolation conditions including four enzyme mixtures (Collagenase type I, Collagenase type I + Trypsin, LiberaseTM and Collagenase type IV) at varying concentrations and incubation times, regarding their efficiency to isolate MSCs from bovine subcutaneous AT. The highest cell yield in combination with a low population doubling time was obtained using LiberaseTM at a concentration of 0.1% for 3 h. MSC identity of the cells was confirmed by tri-lineage differentiation potential and cell surface marker expression. Subsequently, isolated cells were myogenically differentiated using 5-aza-2'-deoxycytidine and galectin-1. mRNA levels of the myogenic regulatory factors (MRF) myogenic factor 5 (MYF5), myogenic differentiation 1 (MYOD1), MYF6, and myogenin (MYOG) were increased, while less paired box 3 (PAX3) mRNA expression was observed when compared to undifferentiated MSCs. The presence of desmin (DES), tropomyosin (TM), and myosin heavy chain (MyHC) in myogenically differentiated bovine AT-MSCs was confirmed using immunofluorescence stainings. When considering MSCs from bovine AT as potential cell source to produce cultured meat, it is recommended to use 0.1% LiberaseTM for 3 h to ensure a high cell yield.

Spinocerebellar ataxia in the Bouvier des Ardennes breed is caused by a KCNJ10 missense variant.

BACKGROUND: In Belgian Malinois, a KCNJ10 variant causes progressive spinocerebellar degeneration. HYPOTHESIS/OBJECTIVES: Describe the clinical, diagnostic, pathological and genetic features of spinocerebellar degeneration in the Bouvier des Ardennes breed. ANIMALS: Five affected Bouvier des Ardennes puppies with spinocerebellar ataxia (SCA), 8 healthy related dogs, and 63 healthy unrelated Bouvier des Ardennes. METHODS: Sequential case study. RESULTS: Clinical signs started at 6 weeks of age in 1 puppy with severe signs of cerebellar disease, and at 7 to 10 weeks of age in the 4 remaining puppies with milder signs of spinocerebellar disease. The first puppy displayed severe intention tremors and rapidly progressive generalized hypermetric ataxia, whereas the 4 others developed a milder progressive SCA. Euthanasia after progression to nonambulatory status was performed by 8 weeks of age in the first puppy, and before 11 months of age in the 4 remaining puppies. Histopathology revealed cerebellar spongy degeneration and a focal symmetrical demyelinating myelopathy. All cases were homozygous for KCNJ10 XM_545752.6:c.986T>C(p.(Leu329Pro)), which is pathogenic for SCA with (or without) myokymia, seizures or both (SAMS) and spongy degeneration and cerebellar ataxia (SDCA) 1 in Belgian Malinois dogs. All sampled parents were heterozygous and none of the healthy dogs were homozygous for this recessive variant. This variant has an allele frequency of 15% in the 63 healthy dogs studied. CONCLUSIONS AND CLINICAL IMPORTANCE: Inherited spinocerebellar degeneration also affects the Bouvier des Ardennes breed and is caused by a KCNJ10 variant. It can present with a spectrum of severity grades, ranging from severe cerebellar to milder spinocerebellar signs.

Phenotypic and genetic aspects of hereditary ataxia in dogs.

Hereditary ataxias are a large group of neurodegenerative diseases that have cerebellar or spinocerebellar dysfunction as core feature, occurring as an isolated sign or as part of a syndrome. Based on neuropathology, this group of diseases has so far been classified into cerebellar cortical degenerations, spinocerebellar degenerations, cerebellar ataxias without substantial neurodegeneration, canine multiple system degeneration, and episodic ataxia. Several new hereditary ataxia syndromes are described, but most of these diseases have similar clinical signs and unspecific diagnostic findings, wherefore achieving a definitive diagnosis in these dogs is challenging. Eighteen new genetic variants associated with these diseases have been discovered in the last decade, allowing clinicians to reach a definitive diagnosis for most of these conditions, and allowing breeding schemes to adapt to prevent breeding of affected puppies. This review summarizes the current knowledge about hereditary ataxias in dogs, and proposes to add a "multifocal degenerations with predominant (spino)cerebellar component" category regrouping canine multiple system degeneration, new hereditary ataxia syndromes that do not fit in 1 of the previous categories, as well as specific neuroaxonal dystrophies and lysosomal storage diseases that cause major (spino)cerebellar dysfunction.