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Biomedical subjects

J Mortera

Publications and source records attributed to J Mortera.

7 recordsLinked to original sources
PubMed2006

Object-oriented Bayesian networks for complex forensic DNA profiling problems.

We describe a flexible computational toolkit, based on object-oriented Bayesian networks, that can be used to model and solve a wide variety of complex problems of relationship testing using DNA profiles. In particular this can account for such complicating features as missing individuals, mutation and null alleles. We illustrate the use of this toolkit with several examples, including disputed paternity with missing or additional measurements, and criminal identification. We investigate the effects on likelihood ratios of introducing mutation and/or null alleles, and show that this can be substantial even when the underlying perturbations are small.

Bayes Theorem↗
PubMed2006

Identification and separation of DNA mixtures using peak area information.

We introduce a new methodology, based upon probabilistic expert systems, for analysing forensic identification problems involving DNA mixture traces using quantitative peak area information. Peak area is modelled with conditional Gaussian distributions. The expert system can be used for ascertaining whether individuals, whose profiles have been measured, have contributed to the mixture. It can also be used to predict DNA profiles of unknown contributors by separating the mixture into its individual components. The potential of our probabilistic methodology is illustrated on case data examples and compared with alternative approaches. The advantages are that identification and separation issues can be handled in a unified way within a single probabilistic model and the uncertainty associated with the analysis is quantified. Further work, required to bring the methodology to a point where it could be applied to the routine analysis of casework, is discussed.

DNA↗
PubMed2003

Probabilistic expert systems for DNA mixture profiling.

We show how probabilistic expert systems can be used to structure and solve complex cases of forensic identification involving DNA traces that might be mixtures of several DNA profiles. In particular, this approach can readily handle cases where the number of contributors to the mixture cannot be regarded as known in advance. The flexible modularity of the networks used also allows us to handle still more complex cases, for example where the finding of a mixed DNA trace is compounded by such features as missing individuals or the possibility of unobserved alleles.

Alleles↗
PubMed2001

Non-fatherhood or mutation? A probabilistic approach to parental exclusion in paternity testing.

The occurrence of germline mutations at microsatellite loci poses problems in ascertaining non-fatherhood status in paternity testing. We describe the appropriate probabilistic analysis for computing the likelihood ratio in favour of paternity while allowing for mutation, for all 18 relevant combinations of seemingly incompatible parental genotypes. We allow arbitrary and possibly different mutation rates in paternal and maternal germlines. We describe a stationary mutation model for expressing the required allele-specific transition mutation rates in terms of overall mutation rates, and compare the likelihood ratios calculated from this and from other mutation models suggested in the literature. We also show how to derive an upper bound on the likelihood ratio, depending only on the overall mutation rate.

Female↗
PubMed1980

The relations between G-6-PD deficiency, thalassemia and malaria. Further analysis of data from Sardinia and the Po Valley.

Discriminant analysis carried out on a set of environmental and sociocultural variables in the Sardinian population suggests that G-6-PD deficiency and thalassemia move along 2 dimensions partially independent of each other. Partial correlation analysis also suggests that malaria, by itself, may exert opposite effects on thalassemia and G-6-PD selection. The present results support the hypothesis that thalassemia may be the primary genetic factor selected by malaria, whereas G-6-PD selection may be a secondary adaptation phenomenon strongly dependent on other genetic and environmental variables.

Consanguinity↗