Introduction: Numerous mutations in the bovine tumour necrosis factor receptor type two (TNF-RII) gene have been identified, but their biological consequences remain poorly understood. The aim of this study was to determine whether polymorphism in the analysed loci of the bovine TNF-RII gene is linked with the size of cell subpopulations naturally infected with bovine leukaemia virus (BLV) which serve important immune functions in the host. Material and Methods: Samples originated from 78 cows. Polymorphisms in the studied gene were determined by PCR-RFLP and DNA sequencing by capillary electrophoresis. BLV infection was diagnosed by the immunofluorescence (IMF) technique and nested PCR. Cell subpopulations were immunophenotyped with IMF. Results: Similar and non-significant differences in the average percentages of TNFα+, IgM+TNFα+, and CD11b+TNFα+ cells infected with BLV were noted in individuals with various genotypes in the polymorphic sites g.-1646T > G and g.16534T > C of the TNF-RII gene, and significant differences in the percentages of these subpopulations were observed between selected microsatellite genotypes (g.16512CA(n)). Conclusion: STR polymorphism and the number of CA dinucleotide repeats in intron 1 of the TNF-RII gene influence the frequency of TNF+, CD11b+TNF+, and IgM+TNF+ subpopulations naturally infected with BLV. Polymorphism in the gene’s other two sites do not affect the size of these cell subpopulations.

Objective-To evaluate molecular abnormalities in the c-kit gene of canine mast cell tumors (MCT) with different grades of cellular differentiation. Sample Population-31 normal tissue specimens from dogs and 45 canine MCT classified according to grade of cell differentiation. Procedure-Genomic DNA extractions were made from canine MCT and normal tissues. Parts of exon 11, intron 11, and exon 12 of the c-kit gene were amplified by use of polymerase chain reaction. These regions were cloned, sequenced, and compared with GenBank sequences of the National Center for Biotechnology International. A statistical analysis was used to compare sequences from canine MCT and normal tissues. Results-A significantly higher percentage of homozygous intron 11 deletion was found in canine MCT (49%) than in normal tissues (13%). This percentage was also higher in moderately and poorly differentiated MCT, compared with well-differentiated MCT. Although no mutations were detected in any of the specimens, a polymorphism at amino acid position 606 of the canine c-kit sequence was found in all the studied sequences. Conclusion and Clinical Relevance-Results indicated a relationship between intron 11 deletion and MCT, and the grade of MCT differentiation. We suggest that intron 11 deletion may be implicated in the pathogenesis of MCT and could be used as a marker for diagnosis and prognosis of canine MCT.

The aim of this study was to look for mutations in the equine ACTN3 gene and to identify sequence variants that might be associated with the phenotype and performance of Brazilian sport horses training for events in a tropical climate. Among 17 such horses direct DNA sequencing and mutation analysis of the exon 15 and the intron-exon boundaries of ACTN3 revealed 2 new sequence variants in the ACTN3 intron 14-15, designated c.1681-86G > A and c.1681-129delA. Wild-type/deletion heterozygotes (A/del) had a lower mean subcutaneous fat layer in the region of the gluteus medius, as measured by ultrasonography, than the del/del homozygotes; the correlation was significant (P = 0.017). This single base-pair deletion in ACTN3 intron 14-15 may have resulted in metabolic changes that led to increased deposition of body fat in the homozygous state. However, neither sequence variant was correlated with the time to fatigue in a test on a high-speed treadmill with an incremental-speed protocol.

Objective—To determine whether a mutation in the fibrillin 2 gene (FBN2) is associated with canine hip dysplasia (CHD) and osteoarthritis in dogs. Animals—-1,551 dogs. Procedures—Hip conformation was measured radiographically. The FBN2 was sequenced from genomic DNA of 21 Labrador Retrievers and 2 Greyhounds, and a haplotype in intron 30 of FBN2 was sequenced in 90 additional Labrador Retrievers and 143 dogs of 6 other breeds. Steady-state values of FBN2 mRNA and control genes were measured in hip joint tissues of fourteen 8-month-old Labrador Retriever–Greyhound crossbreeds. Results—The Labrador Retrievers homozygous for a 10-bp deletion haplotype in intron 30 of FBN2 had significantly worse CHD as measured via higher distraction index and extended-hip joint radiograph score and a lower Norberg angle and dorsolateral subluxation score. Among 143 dogs of 6 other breeds, those homozygous for the same deletion haplotype also had significantly worse radiographic CHD. Among the 14 crossbred dogs, as the dorsolateral subluxation score decreased, the capsular FBN2 mRNA increased significantly. Those dogs with incipient hip joint osteoarthritis had significantly increased capsular FBN2 mRNA, compared with those dogs without osteoarthritis. Dogs homozygous for the FBN2 deletion haplotype had significantly less FBN2 mRNA in their femoral head articular cartilage. Conclusions and Clinical Relevance—The FBN2 deletion haplotype was associated with CHD. Capsular gene expression of FBN2 was confounded by incipient secondary osteoarthritis in dysplastic hip joints. Genes influencing complex traits in dogs can be identified by genome-wide screening, fine mapping, and candidate gene screening.