TAILIEUCHUNG - Báo cáo sinh học: " The analysis of disease biomarker data using a mixed hidden Markov model (Open Access publication)"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: The analysis of disease biomarker data using a mixed hidden Markov model (Open Access publication) | Genet. Sel. Evol. 40 2008 491-509 INRA EDP Sciences 2008 DOI gse 2008017 Available online at Original article The analysis of disease biomarker data using a mixed hidden Markov model Open Access publication Johann C. Detilleux Quantitative Genetics Group Department of Animal Production Faculty of Veterinary Medicine University of Liege Liege Belgium Received 13 September 2007 accepted 3rd March 2008 Abstract - A mixed hidden Markov model HMM was developed for predicting breeding values of a biomarker here somatic cell score and the individual probabilities of health and disease here mastitis based upon the measurements of the biomarker. At a first level the unobserved disease process Markov model was introduced and at a second level the measurement process was modeled making the link between the unobserved disease states and the observed biomarker values. This hierarchical formulation allows joint estimation of the parameters of both processes. The flexibility of this approach is illustrated on the simulated data. Firstly lactation curves for the biomarker were generated based upon published parameters mean variance and probabilities of infection for cows with known clinical conditions health or mastitis due to Escherichia coli or Staphylococcus aureus . Next estimation of the parameters was performed via Gibbs sampling assuming the health status was unknown. Results from the simulations and mathematics show that the mixed HMM is appropriate to estimate the quantities of interest although the accuracy of the estimates is moderate when the prevalence of the disease is low. The paper ends with some indications for further developments of the methodology. hidden Markov model mixed model mastitis somatic cell score 1. INTRODUCTION Studies have shown variability among cows for natural resistance to intramammary infection IMI . Selection is therefore possible but direct measures of IMI are not readily available. Usually information on IMI is .

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