Parens patriease: The right of the state to take charge of the care and custody of minor children or other legal incompetents when their health or safety so requires.
Parentage Judgment: The decision of the court regarding the parentage of a child.
Paternity Index (Likelihood Ratio): For an individual genetic system it is the ratio between the chance that the alleged father may pass the paternal gene compared to the chance that a random man may pass the paternal gene to the child. It is sometimes referred to as the genetic odds in favor of paternity, given the genetic findings in the mother-child-alleged father.
PCR: See polymerase chain reaction.
Phenotype: The measurable genetic markers in a given individual at a specific locus. It may or may not reflect the actual alleles present (see genotype). Example: a person with type A blood is said to have the A phenotype but could have the AO genotype.
Polymerase Chain Reaction: An in vitro method for reproducing DNA in the laboratory. Many millions of copies of a defined short sequence can be made in a short time. Repeated cycling of the reaction allows the new DNA to increase in a geometric fashion.
Polymorphic Locus: A genetic locus for which there are many alleles in existence. The loci used in forensic science are the most polymorphic known.
Population: A defined group of individuals for which databases of gene frequencies are collected by sampling members of the population. In forensic science population databases are collected and maintained by major racial or ethnic group.
Population Database: A random sampling of alleles for a given probe/racial group combination used to determine the frequency of an allele in the population.
Population Substructure: The hypothesis that within the major population groups there exist subgroups whose allele frequency patterns would differ from the parent population to such an extent that the database would not be suitable for forensic use. This phenomena is described by the Wahlund principle.
Polymorphism: The existence of more than one form of a genetic trait.
Population Genetics: A discipline that examines the character and extent of inherited differences within and between populations.
Power of Exclusion (A): The ability of a genetic test to exclude a falsely accused man of paternity and is dependent upon the phenotypes of the mother and child and the ethnic background of the alleged father.
| A = (1 – p) 2 where p = the frequency of the paternal allele in the child. |
Presumption of Paternity: This is a legal assumption that a particular person is the child’s father. This will be binding unless proven otherwise.
Primer: A short piece of DNA, usually synthetic, that defines the specific site on a DNA molecule for a DNA polymerase to start making new DNA. An essential ingredient in the PCR reaction mix.
Prior Probability (Pr): An assigned numerical value of from 0 – 1 (ranging from impossible to certain) of the non-genetic evidence used in evaluating paternity. It is estimated on the basis of the circumstances surrounding the event, e.g. casual acquaintance versus an intimate relationship. A prior probability of 0.5 is considered neutral and is an equal weighting of the nongenetic evidence for and against paternity.
Private case: Any child-related litigation to which the state is not a party.
Pro Se; Pro Se Appearance: When a party handles her own case, i.e., represents herself, she is said to appear “pro se.”
Probability of Paternity (W): A statistical means of describing the likelihood that the alleged father is the biological father of the child. This value incorporates the genetic (Paternity Index) and nongenetic (Prior Probability) information.
Probe: Short segment of DNA that is tagged with a radioactive or chemical tracer and is then used to detect the presence of a particular DNA sequence through hybridization to its complementary sequence.
Product Rule: The concept from elementary probability theory that allows the frequency of occurrence of independent events to be multiplied together to estimate how often they would occur together.
Proficiency Tests: Testing of laboratory personnel performed as part of a quality assurance program. Samples of known composition are supplied to analysts by outside agencies or laboratory management as a way of evaluating and maintaining performance standards.
Protein: A biological polymer made up of amino acids whose structure is coded for by the DNA. Proteins are the primary structural, functional and regulatory molecules of the body. Enzymes are a major class of proteins.
