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Introduction: Accurate quantitative analysis of equine insulin in blood samples is critical for assessing hyperinsulinemia in horses. Although there are various laboratory methods for evaluating equine serum insulin, different immunoassays show significant discrepancies between the determined insulin concentrations and are often not comparable. The aim of this study was to evaluate the Immulite® 1000 chemiluminescent immunoassay (CLIA) to establish independent laboratory and assay-specific cut values to provide an accurate diagnosis of hyperinsulinemia in horses. Thus, the analytical and clinical performance of Immulite® 1000 CLIA in terms of precision (intra- and inter-assay coefficient of variance, CV) and recovery upon dilution were evaluated and compared with radioimmunoassay (RIA), which has been previously validated for use in horses., Material and Methods: Archived serum samples ( n = 106) from six Quarter horse mares enrolled in the glucose phase of a Frequently Sampled Insulin and Glucose Test (FSIGT) study were used to measure blood insulin., Results: The Immulite® 1000 CLIA had good precision with acceptable intra- and inter-assay CVs, adequate recovery on dilution, and a strong correlation with the RIA ( r = 0.974, P < 0.0001), with constant bias resulting in consistently lower values., Discussion: On this basis, the Immulite® 1000 Insulin Assay is valid for measuring equine serum insulin for diagnostic and monitoring purposes when cut values are appropriately adjusted., Competing Interests: NF was employed by Siemens Healthcare Diagnostics Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Go, Hazard, Balasuriya, Chapman, Fitton, Kenéz and Andrews.)

Members of the Alu Yc1 subfamily are distinguished from the older Alu Y subfamily by a signature G-->A substitution at base 148 of their 281-bp consensus sequence. Members of the much older and larger Alu Y subfamily could have by chance accumulated this signature G-->A substitution and be misclassified as belonging to the Alu Yc1 subfamily. Using a Mahanalobis classification method, it was estimated that the "authentic" Alu Yc1 subfamily consists of approximately 262 members in the human genome. PCR amplification and further analysis was successfully completed on 225 of the Yc1 Alu family members. One hundred and seventy-seven Yc1 Alu elements were determined to be monomorphic (fixed for presence) in a panel of diverse human genomes. Forty-eight of the Yc1 Alu elements were polymorphic for insertion presence/absence in diverse human genomes. The insertion polymorphism rate of 21% in the human genome is similar to rates reported previously for other "young" Alu subfamilies. The polymorphic Yc1 Alu elements will be useful genetic loci for the study of human population genetics.