Paternity Index

About: Paternity Index is a research topic. Over the lifetime, 321 publications have been published within this topic receiving 9426 citations.

Statistical confidence for likelihood-based paternity inference in natural populations

Abstract: Paternity inference using highly polymorphic codominant markers is becoming common in the study of natural populations. However, multiple males are often found to be genetically compatible with each offspring tested, even when the probability of excluding an unrelated male is high. While various methods exist for evaluating the likelihood of paternity of each nonexcluded male, interpreting these likelihoods has hitherto been difficult, and no method takes account of the incomplete sampling and error-prone genetic data typical of large-scale studies of natural systems. We derive likelihood ratios for paternity inference with codominant markers taking account of typing error, and define a statistic delta for resolving paternity. Using allele frequencies from the study population in question, a simulation program generates criteria for delta that permit assignment of paternity to the most likely male with a known level of statistical confidence. The simulation takes account of the number of candidate males, the proportion of males that are sampled and gaps and errors in genetic data. We explore the potentially confounding effect of relatives and show that the method is robust to their presence under commonly encountered conditions. The method is demonstrated using genetic data from the intensively studied red deer (Cervus elaphus) population on the island of Rum, Scotland. The Windows-based computer program, CERVUS, described in this study is available from the authors. CERVUS can be used to calculate allele frequencies, run simulations and perform parentage analysis using data from all types of codominant markers.

The y chromosome in forensic analysis and paternity testing

Abstract: The male specificity of the human Y chromosome makes it potentially useful in forensic studies and paternity testing, and markers are now available which will allow its usefulness to be assessed in practice. However, while it can be used confidently for exclusions, the unusual properties of the Y mean that inclusions will be very difficult to make: haplotypes are confined within lineages, so population sub-structuring is a major problem, and many male relatives of a suspect will share his Y chromosome. Y haplotyping is most likely to find application in special instances, such as deficiency cases in paternity testing and in the analysis of mixtures of male and female DNA, or in combination with autosomal markers.

Forensic DNA Evidence Interpretation

Abstract: Biological Basis for DNA Evidence, Peter Gill and John Buckleton Historical and Background Biology Understanding PCR Profiles A Framework for Interpreting Evidence, John Buckleton The Frequentist Approach The Logical Approach The Full Bayesian Approach A Possible Solution A Comparison of the Different Approaches Population Genetic Models, John Buckleton Product Rule Simulation Testing Discussion of the Product Rule and the Subpopulation Model A Complex Case Example - DNA Evidence and Orethral James Simpson Relatedness, John Buckleton and Christopher Triggs Conditional Probabilities Joint Probabilities The Unifying Formula The Effect of Linkage Validating Databases, John Buckleton Which Is the Relevant Population? Population Databases Validating the Population Genetic Model Estimating Q Descriptive Statistics for Databases Sampling Effects, John Buckleton and James Curran Bounds and a Level Methods for Assessing Sampling Uncertainty Minimum Allele Probabilities Discussion of the Appropriateness of Sampling Uncertainty Estimates Mixtures, Tim Clayton and John Buckleton Frequentist Approaches Bayesian Approaches Statistical Evaluation of Mixtures Low Copy Number, John Buckleton and Peter Gill Changes in LCN Profile Morphology The Interpretation of LCN Profiles Non-autosomal Forensic Markers, Simon Walsh, SallyAnn Harbison, and John Buckleton Forensic Mitochondrial DNA Typing Forensic Y Chromosome Analysis Forensic X Chromosome Analysis A Famous Case Example - The Romanovs Parentage Testing, John Buckleton, Tim Clayton, and Chris Triggs Evaluation Of Evidence Paternity Trios: Mother, Child and Alleged Father Non-autosomal DNA Use of the Sub-Population Model of Balding and Nichols to Evaluate the Paternity Index Relatedness in Paternity Cases Multiple Children Inconsistencies in the Mendelian Pattern 'Exclusions' Paternity Trios: Mother, Child and Alleged Father Considering the Possibility of Silent (Null) Alleles Disaster Victim Identification, Identification of Missing Persons, and Immigration Cases, John Buckleton, Chris Triggs, and Tim Clayton Mitochondrial or Nuclear DNA? Human Remains - Obtaining a Profile from Bodily Remains Extraction of DNA from Bone, Tooth, Hair and Nail Complicating Factors DNA Intelligence Databases, Simon Walsh and John Buckleton A Brief History Functional Aspects Legislation Aspects of Forensic Significance Social and ethical considerations Interpretation Issues Associated with DNA Databases

ISFG: Recommendations on biostatistics in paternity testing

Abstract: The Paternity Testing Commission (PTC) of the International Society for Forensic Genetics has taken up the task of establishing the biostatistical recommendations in accordance with the ISO 17025 standards and a previous set of ISFG recommendations specific to the genetic investigations in paternity cases. In the initial set, the PTC recommended that biostatistical evaluations of paternity are based on a likelihood ratio principle – yielding the paternity index, PI. Here, we have made five supplementary biostatistical recommendations. The first recommendation clarifies and defines basic concepts of genetic hypotheses and calculation concerns needed to produce valid PIs. The second and third recommendations address issues associated with population genetics (allele probabilities, Y-chromosome markers, mtDNA, and population substructuring) and special circumstances (deficiency/reconstruction and immigration cases), respectively. The fourth recommendation considers strategies regarding genetic evidence against paternity. The fifth recommendation covers necessary documentation, reporting details and assumptions underlying calculations. The PTC strongly suggests that these recommendations should be adopted by all laboratories involved in paternity testing as the basis for their biostatistical analysis. # 2007 Elsevier Ireland Ltd. All rights reserved.

Parentage analysis with genetic markers in natural populations. I. The expected proportion of offspring with unambiguous paternity.

Abstract: Recent studies indicate that polymorphic genetic markers are potentially helpful in resolving genealogical relationships among individuals in a natural population. Genetic data provide opportunities for paternity exclusion when genotypic incompatibilities are observed among individuals, and the present investigation examines the resolving power of genetic markers in unambiguous positive determination of paternity. Under the assumption that the mother for each offspring in a population is unambiguously known, an analytical expression for the fraction of males excluded from paternity is derived for the case where males and females may be derived from two different gene pools. This theoretical formulation can also be used to predict the fraction of births for each of which all but one male can be excluded from paternity. We show that even when the average probability of exclusion approaches unity, a substantial fraction of births yield equivocal mother-father-offspring determinations. The number of loci needed to increase the frequency of unambiguous determinations to a high level is beyond the scope of current electrophoretic studies in most species. Applications of this theory to electrophoretic data on Chamaelirium luteum (L.) shows that in 2255 offspring derived from 273 males and 70 females, only 57 triplets could be unequivocally determined with eight polymorphic protein loci, even though the average combined exclusionary power of these loci was 73%. The distribution of potentially compatible male parents, based on multilocus genotypes, was reasonably well predicted from the allele frequency data available for these loci. We demonstrate that genetic paternity analysis in natural populations cannot be reliably based on exclusionary principles alone. In order to measure the reproductive contributions of individuals in natural populations, more elaborate likelihood principles must be deployed.