Toxoplasma gondii seroprevalence varies by cat breed

Toxoplasma gondii is a widespread zoonotic parasite that is relevant for veterinary and public health. The domestic cat, the definitive host species with the largest worldwide population, has become evolutionarily and epidemiologically the most important host of T. gondii. The outcome of T. gondii infection is influenced by congenital and acquired host characteristics. We detected differences in T. gondii seroprevalence by cat breed in our previous studies. The aims of this study were to estimate T. gondii seroprevalence in selected domestic cat breeds, and to evaluate whether being of a certain breed is associated with T. gondii seropositivity, when the age and lifestyle of the cat are taken into account. The studied breeds were the Birman, British Shorthair, Burmese, Korat, Norwegian Forest Cat, Ocicat, Persian, and Siamese. Plasma samples were analyzed for the presence of immunoglobulin G antibodies against T. gondii with a commercial direct agglutination test at dilution 1: 40. The samples were accompanied by owner-completed questionnaires that provided background data on the cats. Overall, 41.12% of the 1121 cats tested seropositive, and the seroprevalence increased with age. The Burmese had the lowest seroprevalence (18.82%) and the Persian had the highest (60.00%). According to the final multivariable logistic regression model, the odds to test seropositive were four to seven times higher in Birmans, Ocicats, Norwegian Forest Cats, and Persians when compared with the Burmese, while older age and receiving raw meat were also risk factors for T. gondii seropositivity. This study showed that T. gondii seroprevalence varies by cat breed and identified being of certain breeds, older age, and receiving raw meat as risk factors for seropositivity.Peer reviewe

Nonsense variant in COL7A1 causes recessive dystrophic epidermolysis bullosa in Central Asian Shepherd dogs

A rare hereditary mechanobullous disorder called epidermolysis bullosa (EB) causes blistering in the skin and the mucosal membranes. To date, nineteen EB-related genes have been discovered in human and other species. We describe here a novel EB variant in dogs. Two newborn littermates of Central Asian Shepherd dogs with severe signs of skin blistering were brought to a veterinary clinic and euthanized due to poor prognosis. In post-mortem examination, the puppies were shown to have findings in the skin and the mucosal membranes characteristic of EB. A whole-genome sequencing of one of the affected puppies was performed to identify the genetic cause. The resequencing data were filtered under a recessive model against variants from 31 other dog genomes, revealing a homozygous case-specific nonsense variant in one of the known EB-causing genes, COL7A1 (c.4579C> T, p.R1527*). The variant results in a premature stop codon and likely absence of the functional protein in the basement membrane of the skin in the affected dogs. This was confirmed by immunohistochemistry using a COL7A1 antibody. Additional screening of the variant indicated full penetrance and breed specificity at similar to 28% carrier frequency. In summary, this study reveals a novel COL7A1 variant causing recessive dystrophic EB and provides a genetic test for the eradication of the disease from the breed.Peer reviewe

ANLN truncation causes a familial fatal acute respiratory distress syndrome in Dalmatian dogs

Acute respiratory distress syndrome (ARDS) is the leading cause of death in critical care medicine. The syndrome is typified by an exaggerated inflammatory response within the lungs. ARDS has been reported in many species, including dogs. We have previously reported a fatal familial juvenile respiratory disease accompanied by occasional unilateral renal aplasia and hydrocephalus, in Dalmatian dogs. The condition with a suggested recessive mode of inheritance resembles acute exacerbation of usual interstitial pneumonia in man. We combined SNP-based homozygosity mapping of two ARDS-affected Dalmatian dogs and whole genome sequencing of one affected dog to identify a case-specific homozygous nonsense variant, c.31C>T; p.R11* in the ANLN gene. Subsequent analysis of the variant in a total cohort of 188 Dalmatians, including seven cases, indicated complete segregation of the variant with the disease and confirmed an autosomal recessive mode of inheritance. Low carrier frequency of 1.7% was observed in a population cohort. The early nonsense variant results in a nearly complete truncation of the ANLN protein and immunohistochemical analysis of the affected lung tissue demonstrated the lack of the membranous and cytoplasmic staining of ANLN protein in the metaplastic bronchial epithelium. The ANLN gene encodes an anillin actin binding protein with a suggested regulatory role in the integrity of intercellular junctions. Our study suggests that defective ANLN results in abnormal cellular organization of the bronchiolar epithelium, which in turn predisposes to acute respiratory distress. ANLN has been previously linked to a dominant focal segmental glomerulosclerosis in human without pulmonary defects. However, the lack of similar renal manifestations in the affected Dalmatians suggest a novel ANLN-related pulmonary function and disease association.Peer reviewe

Assembly and Analysis of Unmapped Genome Sequence Reads Reveal Novel Sequence and Variation in Dogs

Correction Volume: 8, Article Number: 11853 DOI: 10.1038/s41598-018-30169-3 Published:AUG 2 2018Dogs are excellent animal models for human disease. They have extensive veterinary histories, pedigrees, and a unique genetic system due to breeding practices. Despite these advantages, one factor limiting their usefulness is the canine genome reference (CGR) which was assembled using a single purebred Boxer. Although a common practice, this results in many high-quality reads remaining unmapped. To address this whole-genome sequence data from three breeds, Border Collie (n = 26), Bearded Collie (n = 7), and Entlebucher Sennenhund (n = 8), were analyzed to identify novel, non-CGR genomic contigs using the previously validated pseudo-de novo assembly pipeline. We identified 256,957 novel contigs and paired-end relationships together with BLAT scores provided 126,555 (49%) high-quality contigs with genomic coordinates containing 4.6 Mb of novel sequence absent from the CGR. These contigs close 12,503 known gaps, including 2.4 Mb containing partially missing sequences for 11.5% of Ensembl, 16.4% of RefSeq and 12.2% of canFam3.1+ CGR annotated genes and 1,748 unmapped contigs containing 2,366 novel gene variants. Examples for six disease-associated genes (SCARF2, RD3, COL9A3, FAM161A, RASGRP1 and DLX6) containing gaps or alternate splice variants missing from the CGR are also presented. These findings from non-reference breeds support the need for improvement of the current Boxer-only CGR to avoid missing important biological information. The inclusion of the missing gene sequences into the CGR will facilitate identification of putative disease mutations across diverse breeds and phenotypes.Peer reviewe

Canine MPV17 truncation without clinical manifestations

Mitochondrial DNA depletion syndromes (MDS) are often serious autosomal recessively inherited disorders characterized by tissue-specific mtDNA copy number reduction. Many genes, including MPV17, are associated with the hepatocerebral form of MDS. MPV17 encodes for a mitochondrial inner membrane protein with a poorly characterized function. Several MPV17 mutations have been reported in association with a heterogeneous group of early-onset manifestations, including liver disease and neurological problems. Mpv17-deficient mice present renal and hearing defects. We describe here a MPV17 truncation mutation in dogs. We found a 1-bp insertion in exon 4 of the MPV17 gene, resulting in a frameshift and early truncation of the encoded protein. The mutation halves MPV17 expression in the lymphocytes of the homozygous dogs and the truncated protein is not translated in transfected cells. The insertion mutation is recurrent and exists in many unrelated breeds, although is highly enriched in the Boxer breed. Unexpectedly, despite the truncation of MPV17, we could not find any common phenotypes in the genetically affected dogs. The lack of observable phenotype could be due to a late onset, mild symptoms or potential tissue-specific compensatory mechanisms. This study suggests species-specific differences in the manifestation of the MPV17 defects and establishes a novel large animal model to further study MPV17 function and role in mitochondrial biology.Peer reviewe

A hypomyelinating leukodystrophy in German Shepherd dogs

Background Shaking puppy syndrome is commonly attributed to abnormal myelination of the central nervous system. Hypothesis/Objectives To report the long-term clinical course and the imaging characteristics of hypomyelinating leukodystrophy in German Shepherd dogs. Animals and Methods Three related litters with 11 affected dogs. Results The 11 affected dogs experienced coarse, side-to-side tremors of the head and trunk, which interfered with normal goal-oriented movements and disappeared at rest. Signs were noticed shortly after birth. Nine dogs were euthanized, 3 dogs underwent pathological examination, and 2 littermates were raised by their breeder. Tremors improved gradually until 6 to 7 months of age. Adult dogs walked with severe residual pelvic limb ataxia. One dog developed epilepsy with tonic-clonic seizures at 15 months of age. Conventional magnetic resonance imaging (MRI) disclosed homogenous hyperintense signal of the entire subcortical white matter in 3 affected 7-week-old dogs and a hypointense signal in a presumably unaffected littermate. Subcortical white matter appeared isointense to gray matter at 15 and 27 weeks of age on repeated MRI. Abnormal white matter signal with failure to display normal gray-white matter contrast persisted into adulthood. Cerebellar arbor vitae was not visible at any time point. Clinical signs, MRI findings, and pathological examinations were indicative of a hypomyelinating leukodystrophy. All parents of the affected litters shared a common ancestor and relatedness of the puppies suggested an autosomal recessive mode of inheritance. Conclusion We describe a novel hypomyelinating leukodystrophy in German Shepherd dogs with a suspected inherited origin.Peer reviewe

Exome sequencing reveals independent SGCD deletions causing limb girdle muscular dystrophy in Boston terriers

Background: Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of inherited autosomal myopathies that preferentially affect voluntary muscles of the shoulders and hips. LGMD has been clinically described in several breeds of dogs, but the responsible mutations are unknown. The clinical presentation in dogs is characterized by marked muscle weakness and atrophy in the shoulder and hips during puppyhood. Methods: Following clinical evaluation, the identification of the dystrophic histological phenotype on muscle histology, and demonstration of the absence of sarcoglycan-sarcospan complex by immunostaining, whole exome sequencing was performed on five Boston terriers: one affected dog and its three family members and one unrelated affected dog. Results: Within sarcoglycan-delta (SGCD), a two base pair deletion segregating with LGMD in the family was discovered, and a deletion encompassing exons 7 and 8 was found in the unrelated dog. Both mutations are predicted to cause an absence of SGCD protein, confirmed by immunohistochemistry. The mutations are private to each family. Conclusions: Here, we describe the first cases of canine LGMD characterized at the molecular level with the classification of LGMD2F.Peer reviewe

Identification of novel genetic risk factors of dilated cardiomyopathy: from canine to human

BackgroundDilated cardiomyopathy (DCM) is a life-threatening heart disease and a common cause of heart failure due to systolic dysfunction and subsequent left or biventricular dilatation. A significant number of cases have a genetic etiology; however, as a complex disease, the exact genetic risk factors are largely unknown, and many patients remain without a molecular diagnosis.MethodsWe performed GWAS followed by whole-genome, transcriptome, and immunohistochemical analyses in a spontaneously occurring canine model of DCM. Canine gene discovery was followed up in three human DCM cohorts.ResultsOur results revealed two independent additive loci associated with the typical DCM phenotype comprising left ventricular systolic dysfunction and dilatation. We highlight two novel candidate genes, RNF207 and PRKAA2, known for their involvement in cardiac action potentials, energy homeostasis, and morphology. We further illustrate the distinct genetic etiologies underlying the typical DCM phenotype and ventricular premature contractions. Finally, we followed up on the canine discoveries in human DCM patients and discovered candidate variants in our two novel genes.ConclusionsCollectively, our study yields insight into the molecular pathophysiology of DCM and provides a large animal model for preclinical studies

Canine DVL2 variant contributes to brachycephalic phenotype and caudal vertebral anomalies

A frameshift deletion variant in the Wnt pathway gene dishevelled 2 (DVL2) is associated with a truncated, kinked tail ("screw tail") in English Bulldogs, French Bulldogs and Boston Terriers. These breeds are also characterized by distinctive morphological traits, including a wide head, flat face and short-limbed dwarfism, which are characteristic of Robinow syndrome in humans, caused by defects in genes such as DVL1 and DVL3. Based on these phenotypic and genetic similarities, it has previously been hypothesized that the canine DVL2 variant results in a syndromic phenotype called the Robinow-like syndrome. In our study, we investigated the distribution of the DVL2 variant in 1954 dogs from 15 breeds, identifying breeds with allele variation and enabling the dissection of the genotype-phenotype correlation for the first time. With CT examinations in American Staffordshire Terriers, we confirmed that the DVL2 allele is associated with caudal vertebral malformations and a brachycephalic phenotype. We also hypothesize that the variant may be linked to additional health conditions, including brachycephalic obstructive airway syndrome and congenital heart defects. Altogether, our study strengthens the role of DVL2 as one of the contributors to the "bulldog type" morphology and features on the spectrum of human Robinow syndrome.Peer reviewe

Bayesian mixed model analysis uncovered 21 risk loci for chronic kidney disease in boxer dogs

Author summaryChronic kidney disease (CKD) is described as a set of heterogeneous disorders affecting kidney structure and function. CKD is common in dogs and has been diagnosed in nearly all breeds. In this study, we identified 21 genetic regions associated with CKD in a boxer population and investigated the relevant genes and putative regulatory variants in these regions. Studies of canine CKD may help to better understand the pathology of kidney disease in both dogs and humans, and shows an important potential for early identification of high-risk individuals. Chronic kidney disease (CKD) affects 10% of the human population, with only a small fraction genetically defined. CKD is also common in dogs and has been diagnosed in nearly all breeds, but its genetic basis remains unclear. Here, we performed a Bayesian mixed model genome-wide association analysis for canine CKD in a boxer population of 117 canine cases and 137 controls, and identified 21 genetic regions associated with the disease. At the top markers from each CKD region, the cases carried an average of 20.2 risk alleles, significantly higher than controls (15.6 risk alleles). An ANOVA test showed that the 21 CKD regions together explained 57% of CKD phenotypic variation in the population. Based on whole genome sequencing data of 20 boxers, we identified 5,206 variants in LD with the top 50 BayesR markers. Following comparative analysis with human regulatory data, 17 putative regulatory variants were identified and tested with electrophoretic mobility shift assays. In total four variants, three intronic variants from the MAGI2 and GALNT18 genes, and one variant in an intergenic region on chr28, showed alternative binding ability for the risk and protective alleles in kidney cell lines. Many genes from the 21 CKD regions, RELN, MAGI2, FGFR2 and others, have been implicated in human kidney development or disease. The results from this study provide new information that may enlighten the etiology of CKD in both dogs and humans