Abstract People suffering from uncommon diseases often do not benefit from the advances in medical research due to lack of research. One such disease is angiosarcoma, a highly aggressive cancer originating from blood vessels with risk factors including toxic exposure, radiotherapy and lymphedema. Angiosarcoma in dogs (commonly called hemangiosarcoma) is a very similar disease with much higher prevalence, comprising up to 7% of all canine malignancies. For both species, an accurate diagnostic method is needed for more favorable outcome. We developed a biomarker discovery pipeline consisting of a high-throughput biomarker discovery platform and a database for data mining and statistical analysis for candidate identification. The platform screens for differential glycosylation of serum glycoproteins as potential biomarkers utilizing 20 individual lectins followed by direct coupling to tandem mass spectrometry. The database facilitates the identification of differential glycosylation and produces a ranked list of potential biomarker candidates. Using this pipeline, sera from 10 dogs with hemangiosarcoma with 10 age and sex-matched control sera were processed and analyzed. Candidates from the database were ranked based on its ability to classify normal and cancer. The ranked list of candidates for this screen composed of glycoproteins involved in cell migration, tumor immune response, and glycoproteins reported to be altered in human and canine angiosarcoma and other cancer types. Some examples will be shown to illustrate the change in specific glycosylation structures associated with cancer as measured by binding to specific lectin(s) while binding to other lectins are not changed. These glycosylation-specific changes are potentially more specific diagnostic biomarkers than circulating proteins alone. We are currently validating the identified candidates and pursuing the development of clinical tests to improve diagnosis and clinical outcomes of angiosarcoma for both dogs and humans. Citation Format: Eunju Choi, David Chen, Kim-Anh Lê Cao, Helle Bielefeldt-Ohmann, Caroline A. O'Leary, Michelle M. Hill. Diagnostic serum biomarkers for canine hemangiosarcoma: a potential model of human angiosarcoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2499. doi:10.1158/1538-7445.AM2013-2499
To identify the genetic cause of isolated canine ectopia lentis, a well-characterized veterinary disease commonly referred to as primary lens luxation (PLL) and to compare the canine disease with a newly described human Weill-Marchesani syndrome (WMS)-like disease of similar genetic etiology.Genomewide association analysis and fine mapping by homozygosity were used to identify the chromosomal segment harboring the PLL locus. The resequencing of a regional candidate gene was used to discover a mutation in a splice donor site predicted to cause exon skipping. Exon skipping was confirmed by reverse transcription-polymerase chain reaction amplification of RNA isolated from PLL-affected eyes and from skin fibroblast cultures from PLL-affected dogs. An allelic discrimination assay was used to genotype individual dogs at the splice donor site mutation.The PLL locus was mapped to a 664-kb region of canine chromosome 3 containing regional candidate gene ADAMTS17. Resequencing ADAMTS17 revealed a GT-->AT splice-donor-site mutation at the 5' end of intron 10. The predicted exon 10 skipping and resultant frame shift were confirmed with RNA derived from PLL-affected dogs. The ADAMTS17 mutation was significantly associated with clinical PLL in three different dog breeds.A truncating mutation in canine ADAMTS17 causes PLL, a well-characterized veterinary disease, which can now be compared to a recently described rare WMS-like disease caused by truncating mutations of the human ADAMTS17 ortholog.
The prevalence of spotted fever group rickettsial infection in dogs from a remote indigenous community in the Northern Territory (NT) was determined using molecular tools. Blood samples collected from 130 dogs in the community of Maningrida were subjected to a spotted fever group (SFG)-specific PCR targeting the ompB gene followed by a Rickettsia felis-specific PCR targeting the gltA gene of R. felis. Rickettsia felis ompB and gltA genes were amplified from the blood of 3 dogs. This study is the first report of R. felis infection in indigenous community dogs in NT.
Purpose: Primary lens luxation (PLL) in dogs is an inherited disease in which the lens is displaced from its normal position. A truncating mutation in the ADAMTS17 orthologue on CFA03 is reported to cause PLL in several breeds, mostly terriers. However, the complex inheritance pattern of PLL in miniature bull terriers (MBTs) suggests that other loci may have a modifying effect on the ADAMTS17 mutation. This study aimed to detect such loci increasing risk of PLL in Australian MBTs. Methods: More than 170,000 single-nucleotide polymorphisms (SNPs) across the canine genome were genotyped in 23 PLL-affected and 73 normal Australian MBTs, and association between the PLL phenotype and the genetic markers was investigated by using general mixed effects Cox model survival analysis. Results: The highest association peaks, other than that associated with the ADAMTS17 mutation (P = 2.2e-05), were SNP BICF2G630420272 located at 62.2 Mb on chromosome 15 (P = 7.8e-05) and the region between 30 Mb and 32.5 Mb on chromosome 1 (P = 9.3e-05). Joint analysis showed that the PLL-associated allele of the BICF2G630420272 SNP increased risk of PLL in the presence of the ADAMTS17 mutation (P = 8.117e-04). Candidate genes in the two regions of interest included CPE on chromosome 15 and CTGF on chromosome 1. The ADAMTS17 mutation was also associated with abnormal foot and nail shapes, pedal hyperkeratosis, and persistent pupillary membranes. Conclusions: Two loci with potentially enhancing effects on the ADAMTS17 mutation were associated with PLL in Australian MBTs. Association of the ADAMTS17 mutation with possible pedal skeletal abnormalities in MBTs supports PLL in this breed and Weill-Marchesani syndrome-like disease in humans as being homologous diseases.
Rickettsia felis causes flea-borne spotted fever in humans worldwide. The cat flea, Ctenocephalides felis, serves as vector and reservoir host for this disease agent. To determine the role of dogs as potential reservoir hosts for spotted fever group rickettsiae, we screened blood from 100 pound dogs in Southeast Queensland by using a highly sensitive genus-specific PCR. Nine of the pound dogs were positive for rickettsial DNA and subsequent molecular sequencing confirmed amplification of R. felis. A high prevalence of R. felis in dogs in our study suggests that dogs may act as an important reservoir host for R. felis and as a potential source of human rickettsial infection.
Polycystic Kidney Disease is an autosomal dominant disease common in some lines of Bull Terriers (BTPKD). The disease is linked to the canine orthologue of human PKD1 gene, Pkd1, located on CFA06, but no disease-associated mutation has been reported. This study sequenced genomic DNA from two Bull Terriers with BTPKD and two without the disease. A non-synonymous G>A transition mutation in exon 29 of Pkd1 was identified. A TaqMan® SNP Genotyping Assay was designed and demonstrated the heterozygous detection of the mutation in 47 Bull Terriers with BTPKD, but not in 102 Bull Terriers over one year of age and without BTPKD. This missense mutation replaces a glutamic acid residue with a lysine residue in the predicted protein, Polycystin 1. This region of Polycystin 1 is highly conserved between species, and is located in the first cytoplasmic loop of the predicted protein structure, close to the PLAT domain and the second transmembrane region. Thus, this change could alter Polycystin 1 binding or localization. Analytic programs PolyPhen 2, Align GVGD and SIFT predict this mutation to be pathogenic. Thus, BTPKD is associated with a missense mutation in Pkd1, and the application of this mutation specific assay could reduce disease transmission by allowing diagnosis of disease in young animals prior to breeding.
Genetic variants that are associated with susceptibility to type 2 diabetes (T2D) are important for identification of individuals at risk and can provide insights into the molecular basis of disease. Analysis of T2D in domestic animals provides both the opportunity to improve veterinary management and breeding programs as well as to identify novel T2D risk genes. Australian-bred Burmese (ABB) cats have a 4-fold increased incidence of type 2 diabetes (T2D) compared to Burmese cats bred in the United States. This is likely attributable to a genetic founder effect. We investigated this by performing a genome-wide association scan on ABB cats. Four SNPs were associated with the ABB T2D phenotype with p values <0.005. All exons and splice junctions of candidate genes near significant single-nucleotide polymorphisms (SNPs) were sequenced, including the genes DGKG, IFG2BP2, SLC8A1, E2F6, ETV5, TRA2B and LIPH. Six candidate polymorphisms were followed up in a larger cohort of ABB cats with or without T2D and also in Burmese cats bred in America, which exhibit low T2D incidence. The original SNPs were confirmed in this cohort as associated with the T2D phenotype, although no novel coding SNPs in any of the seven candidate genes showed association with T2D. The identification of genetic markers associated with T2D susceptibility in ABB cats will enable preventative health strategies and guide breeding programs to reduce the prevalence of T2D in these cats.
Abstract Background Canine atopic dermatitis is an allergic inflammatory skin disease common in West Highland white terriers. A genome-wide association study for atopic dermatitis in a population of West Highland white terriers identified a 1.3 Mb area of association on CFA17 containing canine protein tyrosine phosphatase non-receptor type 22 (lymphoid) PTPN22 . This gene is a potential candidate gene for canine atopic dermatitis as it encodes a lymphoid-specific signalling mediator that regulates T-cell and possibly B-cell activity. Findings Sequencing of PTPN22 in three atopic and three non-atopic West Highland white terriers identified 18 polymorphisms, including five genetic variants with a bioinformatically predicted functional effect. An intronic polymorphic repeat sequence variant was excluded as the cause of the genome-wide association study peak signal, by large-scale genotyping in 72 West Highland white terriers (gene-dropping simulation method, P = 0.01). Conclusions This study identified 18 genetic variants in PTPN22 that might be associated with atopic dermatitis in West Highland white terriers. This preliminary data may direct further study on the role of PTPN22 in this disease. Large scale genotyping and complementary genomic and proteomic assays would be required to assess this possibility.
Abstract Human and canine atopic dermatitis (AD) share an association with IgE specific to environmental allergens, but few studies have evaluated serum allergen‐specific IgE in nonatopic dogs. This study compared serum allergen‐specific IgE levels in 30 atopic and 18 nonatopic West Highland white terriers. Atopic dermatitis was confirmed using standard criteria. Nonatopic dogs were over 5 years of age and had no clinical signs or history of AD. Serum allergen‐specific IgE levels were measured with Allercept ® IgE ELISAs using a 48‐allergen Australian panel. Positive reactions were defined as ≥150 ELISA absorbance units. Intradermal tests were performed in 16 atopic dogs, either at the time of or at various times prior to serum collection. In atopic dogs, the most common positive ELISA and intradermal test results were to Dermatophagoides farinae (11 of 30 dogs), but there were no statistically significant correlations between results from the two methods for any allergen. In nonatopic dogs, multiple high‐positive ELISA reactions were reported to 45 of 48 allergens, most commonly D. farinae and Tyrophagus putrescentiae ( 17 of 18 dogs each). Positive ELISA results in nonatopic dogs were statistically significantly higher than those in atopic dogs for 44 of 48 allergens, including two allergens ( D. farinae and Dermatophagoides pteronyssinus ) commonly regarded as significant in canine AD. In conclusion, positive allergen‐specific IgE ELISAs were not specific for canine AD, and high allergen‐specific IgE levels were seen in nonatopic dogs. The clinical significance of this and whether it characterizes a protective phenotype is unclear.
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