Summary of concepts Human DNA Analysis and Interpretation

Regulation | 24-03-2021

This document contains keywords for concepts of which an expert in the field of DNA should minimally have a basic knowledge.

Forensic biology

Sources of DNA evidence
Crime scene investigation and laboratory analysis of biological evidence
Identification and presumptive testing of body fluids (blood, semen, saliva)
Confirmatory assays for body fluid identification (immunoassays)
Uncertainty concerning attribution of DNA (particularly at low levels) to specific body fluids

The structure of DNA and the variability of the human DNA genome
Loci, alleles, genotypes and DNA profiles
Polymorphisms commonly used for DNA testing
The molecular biological basis of forensic DNA tests; using the DNA profile to identify a forensic sample
Extraction and quantification of DNA
Polymerase chain reaction
Short tandem repeats and mutation processes
Forensic multiplex STR typing kits
DNA separation by CE and LIF detection
Analysis of results, including the use of ladders for fragment sizing, use of analytical thresholds and identification of artefacts such as stutter, “pull-up” and identification of mixed samples.

Quality control and quality assurance of forensic DNA analysis
Laboratory accreditation, personnel certification and proficiency testing
Validation studies
Laboratory error rates
Understanding and minimizing the risk of contamination in the forensic process: methods of reducing the occurrence of contamination and detecting when it has occurred
Continuous improvement and quality

Likelihood Ratio (LR)
Bayes Theorem
Product rule to calculate the probability of independent variables
DNA mixture deconvolution and recommended procedures for analysing mixed samples
Accounting for relatives, where applicable, in calculating evidential strength
Database issues
Inclusion criteria and search (im)possibilities of the national DNA database including the detection of false negative and false positive matches
Population Genetics
Hardy-Weinberg equilibrium/Linkage equilibrium
Population Substructure
Allele frequencies, genotype probabilities
Applying the product rule for independent events
Conditional match probabilities
Fst/Theta population substructure correction; correction for possible allele dropout
Sampling variation in construction of DNA population databases
Proper Interpretation of the Evidence
Common Logical Fallacies (Prosecution/Defence Fallacy)
Evidential strength of database match
DNA database search controversy
Avoidance of cognitive bias

Evaluation of potential low template DNA typing results.
Allele and/or locus dropout due to degradation, preferential amplification, stochastic effects and stochastic thresholds
Replication and consensus DNA profiles
Approaches for the statistical evaluation of DNA profiles from low template DNA samples

Inheritance of genetic polymorphisms
Technical procedures for determining kinship
Statistical evaluation of kinship (e.g. paternity index, sibling index, Bayesian networks)
Incorporation of the presence of mutations and null-alleles in the statistical evaluation
Principles of disaster/mass identification
Principles of familial searching in databases
Use of Y-STR and mtDNA analysis to narrow candidate lists from familial searching in databases

Evolution and migration of Homo sapiens
Population genetics of externally visible characteristics
Principles of determining the geographic origin of an individual
Principles of determining externally visible characteristics
Knowledge about genes involved in the biosynthesis of melanine (skin and hair pigmentation, iris colour)
Technical procedures for determining geographic origin or externally visible characteristics
Approaches for the interpretation of genotyping results for determining geographic origin or externally visible characteristics
Knowledge of the limitations of determining geographic origins or externally visible characteristics

Mitochondrial DNA evolution and its consequences for forensic analysis
Matrilineal inheritance, variable mutation rates, heteroplasmy and principles for evaluating close non-matching mtDNA sequences
Laboratory analysis of mitochondrial DNA (e.g. Sanger sequencing, mini-sequencing)
Population genetics of mitochondrial DNA haplotypes
Use of mitochondrial DNA databases (EMPOP)
Statistical evaluation of mitochondrial DNA matches

Understanding of the principles of case assessment and interpretation (CAI)4 and the necessity for the following criteria: balance, logic, robustness and transparency
Formulation and evaluation of appropriate hypotheses
Understanding use of data and experience for evaluation of results given activity level hypotheses:
- Knowledge concerning transfer of cells and DNA (primary, secondary, tertiary)
- Knowledge concerning persistence of DNA and the impact of e.g. environmental conditions
- Extensive experience of forensic DNA analysis and interpretation in forensic casework
- Transparency regarding any limitations of the data used
Understanding of the principles of probabilistic (Bayesian) networks in evidence interpretation