HypervariableAn area on the DNA which can have many different alleles in differing sequences. Hypervariable Control RegionThe D-loop of mitochondrial DNA in which base pairs of nucleotides repeat. I
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Top ImmunoglobulinA general term for the kind of globular blood proteins that constitute antibodies. A tetrameric protein composed of two identical light chains and two identical heavy chains. Specific proteins produced by derivatives of B lymphocytes that interact with and help protect an organism from specific antigens. IncludedTwo samples could have come from the same source. Inclusion (Failure to Exclude) The inability to exclude an individual as a possible source of a biological sample. This occurs when all types from a specific location in the DNA of a known individual are also present in the types for that specific location in the DNA obtained from an evidence sample. InconclusiveA situation in which no conclusion can be reached regarding testing done due to one of many possible reasons (e.g., no results obtained, uninterpretable results obtained, no exemplar/standard available for testing). Indigo dyeA blue-colored dye that is derived from several plant species and commonly used to dye denim for blue jeans. A known PCR inhibitor. IndividualizationIn forensic science, the process of attempting to associate an item of evidence with one and only one source. InhibitorsA substance that interferes with or prevents the polymerase chain reaction. Inner Cuticle Margin
The border between the cuticle and the cortex. Intercalating dyeA chemical that can insert itself between the stacked bases at the center of the DNA double helix, possibly causing a frameshift mutation. Internal Size Standard (ISS)Specific DNA fragments of known sizes which are defined and used to size unknown fragments. Internal testingAn internal test is one that is created and administered by the laboratory itself.
Intimate SampleAn intimate sample is generally referred to a biological sample obtained from a source other than the mouth (saliva) and head (hair). Irresolvable mixtureA DNA profile where multiple individuals have contributed biological material and no profile is more or less apparent than any other and the developed alleles cannot be isolated to a single source. Isoamyl AlcoholA chemical used in organic extractions to reduce the foaming of reagents, making it easier to detect the interface between the organic and aqueous phases. IsoenzymeMultiple forms of enzymes arising from genetically determined differences in primary structure. The term does not apply to those derived by modification of the same primary sequence. J
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Top John Doe WarrantA warrant used when crime scene evidence yields a DNA profile but the individual corresponding to the DNA profile is unknown. In lieu of the suspect's name, the warrant will be filed as "John Doe" and cite the DNA profile. Junk DNAStretches of DNA that do not code for genes; "most of the genome consists of junk DNA." K
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Top KeratinAny of the various sulphur-containing fibrous proteins that form chemical basis for keratinized epidermal tissues such as hair, nails, feathers, and horns of animals. KinkedHair that is closely curled or twisted. Known samplesA DNA sample for which the source is known. These samples are generally obtained from the victim and/or suspected perpetrator of a crime, as well as from other persons whose DNA might be reflected when samples of the evidence are analyzed (could include a boyfriend, husband, or other third-party). These samples are also referred to as reference samples, since they serve as a reference to which the unknown DNA samples are compared with the goal of identifying the source of the unknown DNA samples. L
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TopLanugoThe fine hairs found on the human fetus. Latent printA print impression that is not readily visible, made by contact with a surface. LDISThe Local DNA Index System of CODIS, which uploads forensic and offender DNA profiles to the State DNA Index System, or SDIS. Length heteroplasmy The presence of mtDNA molecules that differ in length. Likelihood ratioThe ratio of two probabilities of the same event under different hypotheses. In DNA testing often expressed as the ratio between the likelihood that a given profile came from a particular individual and the likelihood that it came from a random unrelated person. Note that in this case the likelihood of each event does not add to give 1 (100% likelihood) as it does not incorporate the possibility of error or that the profiles came from twins or other near relatives. Linkage Equilibrium
When two or more genetic loci appear to segregate randomly in a given population. The genotypes appear randomly with respect to each other.
LipopolysaccharidesA large molecule containing a lipid and a carbohydrate. Locard's Exchange Principal
States that every time someone enters an environment, something is added to and removed from it. The principle is sometimes stated as "every contact leaves a trace," and applies to contact between individuals as well as between individuals and a physical environment. Local (LDIS)The Local DNA Index System of CODIS which uploads forensic and offender DNA profiles to the State DNA Index System, or SDIS. Locus (pl. loci)The specific physical location of a gene on a chromosome. Looped Cuticle
A looped cuticle is a condition in which the distal edges of the cuticle scales are curved from or cup toward the hair shaft.
Low copy numberRefers to examination of less than 100pg (picograms) of input DNA. M
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TopMacroscopicA term that describes characteristics large enough to be perceived without magnification; in forensic hair examination, this typically applies to unmounted hairs. MagnificationThe height of the image divided by the height of the object. The apparent enlargement of an object by an optical instrument. Major contributor profileA DNA profile where multiple individuals have contributed biologic material and one individual's DNA profile is more apparent. MarkerPieces of DNA sequence of known locations on chromosomes that are used to identify the specific genetic variations an individual possesses. MatchGenetic profiles are said to "match" when they have the same allele designations at every loci. MeanThe mean of sample is calculated by taking the sum of all data values and dividing by the total number of data values. Measurement scaleAn object showing standard units of length (e.g., ruler) used in photographic documentation of an item of evidence. MedialTowards the long axis of the hair. MedullaA series of air- or fluid-filled cells along the central axis of the hair. Medullary ContinuityThe continuous or discontinuous nature of the medulla. MelaninThe pigment occurring in plants, animals, and protista. It is responsible for skin and hair pigmentation. Two forms of melanin, eumelanin and phaeomelanin, determine the color of human hair. Melting Temperature TmThe temperature at which one-half of a particular DNA duplex will dissociate and become single strand DNA. Microbial Epidemiologymicrobial: relating to a microbe or microbes; epidemiology: the study or the distribution and determinants of health-related states or events in specified populations, and the application of this study to control health problems. MicroscopeAn instrument consisting essentially of a tube 160 mm long, with an objective lens at the distant end and an eyepiece at the near end. The objective forms a real aerial image of the object in the focal plane of the eyepiece where it is observed by the eye. MicroscopicA term for objects which are too small to be resolved by the unaided eye. Midshaft RegionThe region of the hair between the proximal and distal ends. Minisatellite Variant Repeat (MVR)The temperature at which one-half of a particular DNA duplex will dissociate and become single strand DNA. Mitochondrial DNA (mtDNA)The DNA found in the many mitochondria found in each cell of a body. The sequencing of mitochondrial DNA can link individuals descended from a common female ancestor. MongoloidAn archaic anthropological term designating peoples originating from Asia, excluding the Indian subcontinent but including the Native Americans. MonilethrixMonilethrix is a hair disorder that results in periodic nodes or beading along the length of the hair with intervening, tapering constrictions that are not medullated. MorphologyShape, form, external structure, or arrangement, especially as an object of study or classification mtDNA typesA mtDNA type is the sequence of a region of mtDNA. Common sources of mtDNA are hairs, skeletal remains, and teeth. MultiplexedA system for analyzing several loci at once. MutationDamaged or changed DNA anywhere along the DNA strand. N
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Top National DNA Index System (NDIS) Authorized by the DNA Identification Act of 1994, the FBI administers this national index. NDIS compares DNA profiles associated with a crime scene to DNA profiles collected from known convicted offenders, as well as to other crime scene profiles. When the DNA profiles are uploaded to NDIS, they are searched against the other DNA profiles submitted by other participating states. National Research Council (NRC)The National Research Council was convened in 1989. In 1996 the NRC filed the report The Evaluation of Forensic DNA Evidence (referred to as NRC II). This document revised and expanded the initial report written in 1992 (NRC I). These recommendations are recognized by U.S. courts. NegroidAn archaic anthropological term designating most of the peoples originating from Africa. No resultsA situation in which no interpretable results are obtained from testing a DNA sample. A finding of no results can be due to the absence of DNA, insufficient DNA, or substances that inhibit the PCR process, among others. Non-conformancesInconsistencies in laboratory practices that do not meet accreditation standards. NonmatchAn individual is eliminated as the source of a biological sample. This occurs when one or more types from a specific location in the DNA of a known individual are not present in the type(s) for that specific location in the DNA obtained from an evidence sample. Nonporous ContainerPackaging through which liquids or vapors cannot pass (e.g., glass jars or metal cans). Nuclear DNAThe DNA found in the nucleus of a cell. NucleasesOne of the several classes of enzymes that degrade nucleic acid. An enzyme that can degrade DNA or RNA by breaking phosphodiester bonds. NucleatedA nucleus or occurring in the nucleus. NucleusThe cellular organelle that contains most of the genetic material. Numerical apertureA measure of the information-collecting ability of a microscope optic. The greater the NA, the better the resolving ability. It is a measure of the light-gathering capacity of the lens system and determines its resolving power and depth of field. O
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Top Objective testA test which having been documented and validated is under control so that it can be demonstrated that all appropriately trained staff will obtain the same results within defined limits. These defined limits relate to expressions of degrees of probability as well as numerical values. Off Ladder (OL) AllelesAlleles that size outside allele categories represented in the ladder. Offender HitA CODIS match between a crime scene profile and an offender profile. Offender IndexDNA profiles developed from qualifying offenders and uploaded into CODIS are maintained in the offender index of the database. Ohm's LawThe amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive forces impressed on the circuit and inversely proportional to the total resistance of the circuit. OligonucleotidesA molecule usually composed of 25 or fewer nucleotides; used as a DNA synthesis primer. Optical Density (OD)Synonymous with absorbance. Absorbance is the logarithm of the ratio of incident to transmitted radiant power through a sample. Outer Cuticle MarginThe border of the outermost edge of the cuticle. Ovoid BodiesOval-shaped heavily pigmented bodies that may occur in the hair cortex. P
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Top Partial profileDNA evidence that does not yield identifiable results in all 13 core loci. Partially degraded DNAForensic DNA evidence exposed to environmental conditions that may prevent it from yielding a usable profile. Paternal inheritance
Genetic material which is inherited from one's father; for example, the possibility that mtDNA can be inherited from one's father.
Paternity or System Index (PI or SI)A statistic that compares the likelihood that a genetic marker (allele) that the alleged father passed to the child to the probability that a randomly selected unrelated man of similar ethnic background could pass the allele to the child. PCR InhibitorsA substance that interferes with the Polymerase Chain Reaction (PCR) process. Examples of PCR inhibitors include dyes, soil, chemicals, and heme (hemoglobin). Peripheral RegionThe peripheral region is the portion of the hair toward the outermost areas of the hair, including the cuticle and the outer areas of the cortex, distant from the medullary or central region. Personal Protective Equipment (PPE)Articles such as disposable (latex) gloves, masks, shoe covers, and eye protection that are utilized to provide a barrier to keep biological or chemical hazards from contacting the skin, eyes, and mucous membranes and to avoid contamination of the crime scene. PhenolA chemical used in organic extraction. Polysaccharides and proteins are soluble in phenol, allowing for their separation from DNA. C6H5OH. See figure to the right. PhenotypeThe detectable outward manifestations of a specific genotype; the physical characteristics of a living object. PigmentationColoration or discoloration by formation or deposition of pigment in the tissues. In a forensic hair examination, the description of the aggregation, distribution, and density of pigment granules. Pili AnnulatiPili annulati is a hair disorder that results in ringed or banded hair, alternating bright and dark bands in the hair shaft. The dark bands are a manifestation of the abnormal air spaces in the cortex. Pili BifurcatiA genetic hair disorder characterized by two hairs joined at the shaft along their entire length. Pili TortiA genetic hair disorder characterized by the hair shaft being flattened and twisted 180 degrees numerous times along its axis. It is usually found at irregular intervals along the shaft. Polymerase Chain Reaction (PCR)A process used in DNA identification testing in which one or more specific small regions of the DNA are copied using a DNA polymerase enzyme so that a sufficient amount of DNA is generated for analysis. PolymorphicVariable, more than one kind. PolymorphismVariations in DNA sequences in a population that are detected in human DNA identification testing. PolypurineA stretch of adenine and/or guanine. PolypyrimidineA stretch of cytosine and/or thyamine. PopStats
FBI CODIS software program used to perform statistical DNA match estimates. Population GeneticsThe study of the distribution of genes in populations and of how the frequencies of genes and genotypes are maintained or changed. Postmortem Root BandingAn opaque ellipsoidal band, composed of parallel elongated air spaces, which appear on the proximal portion of hair shafts from postmortem hairs, likely to be in the anagen growth phase. Preferential AmplificationImbalanced amplification or lack of amplification at a locus. Presumptive TestA screening test used to indicate the possible presence of the named body fluid. PrimerA segment of DNA or RNA that is complementary to a given DNA sequence and that is needed to initiate replication by DNA polymerase. Primer dimerFormed by intermolecular interactions between the two primers (i.e., self-dimers and cross-dimers). ProbabilityThe chance of observing a particular future event; a simple ratio of the number of observed events divided by the total number of possible events. Probability calculationsPredictions based on small sampling of a larger population. Probability of ExclusionThe probability that a random individual would be excluded as the source of analyzed DNA evidence. Probability of inclusionThe probability that a random individual would be included as a potential source of analyzed DNA evidence. Probability of PaternityA formula that tests the hypothesis that the accused is the biological father of the child. ProbeDefined nucleic acid (DNA or RNA) that can be used to identify, usually through autoradiography, specific DNA or RNA molecules bearing the complementary sequence. Product ruleThe product rule calculates the expected chance of finding a given STR (short tandem repeat) profile within a population by multiplying the frequency of occurrence of the combination of alleles (genotype) found at a single locus, by the frequency of occurrence of the genotype found at the second locus, by the frequency of occurrence, in turn, of each of the other genotypes at the remaining STR loci. Proficiency TestA proficiency test is a quality assurance measure used to monitor performance of an examiner. Proficiency testingA DNA proficiency test uses biological samples to assess a lab analyst's ongoing competency and the laboratory's ability to produce accurate results.
ProtamineProtein that binds DNA in sperm, replacing histones and allowing chromosomes to become more highly condensed than possible with histones. Proteinase KAn endolytic protease that cleaves peptide bonds at the carboxylic sides of aliphatic, aromatic, or hydrophobic amino acids. Proteinase K in the extraction buffer inactivates nucleases and aids in lysis of epithelial and white blood cells to free nuclear DNA. Proximal EndThe portion of the hair towards the root. Pull-up
Specifically related to ABI Gene Scan® software, a peak seen in one color that is not due to the presence of DNA, but to incorrect compensation for the spectral overlap of the four dyes used in detecting multiple loci in one reaction. See also:
Artifact Q
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Top Quality Assurance (QA)A program conducted by a laboratory to ensure accuracy and reliability of tests performed. Quality Assurance StandardsThe standards originated from the DNA Advisory Board and are maintained by the FBI; they place specific requirements on labs involved in forensic DNA analysis, both casework and convicted offender databasing. QuantitationMethod used to determine the quantity of "x" in a given sample. In this context, it refers to the quantity of DNA in a sample and is usually reported as ng/µl. Quantitative PCR (qPCR)Sometimes referred to in forensic science as real-time PCR. An amplification process that detects and measures the accumulation of fluorescent dyes as the reaction progresses. The initial quantity of DNA in the sample is detected by monitoring the exponential growth phase of the reaction and measuring the cycle number at which the fluorescent intensity of the sample overcomes the background noise or threshold. Questioned SampleA sample recovered or collected, about which there are questions, for a forensic examination. R
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Top Racial groupA group of people defined by race, color, nationality, and ethnic or national origins. Random match probabilityThe probability that the DNA in a random sample from the population has the same profile as the DNA in the evidence sample. Randomly Amplified Polymorphic DNA MarkersRandom amplification of polymorphic DNA. A method for identifying differences between genomes of different individuals by PCR with a single short (usually 10-base) primer, which will anneal with complementary sequence at undetermined positions in the genome. Reciprocal DiscoverySome jurisdictions enable a prosecutor by motion to request that the defense provide specific discovery material to the prosecution. Recombinant DNA - Altered DNA resulting from the insertion into the chain, by chemical, enzymatic, or other biological means, of a sequence (a whole or partial chain of DNA) not originally (biologically) present in that chain.
RecombinationThe reversal of coupling phase I meiosis as gauged by the resulting phenotype. See also Recombinant DNA above. Reference SamplesA standard/reference sample is material of a verifiable/documented source which, when compared with evidence of an unknown source, shows an association or linkage between an offender, crime scene, and/or victim (e.g., a carpet cutting taken from a location suspected as the point of transfer for comparison with the fibers recovered from the suspect's shoes, a sample of paint removed from a suspect vehicle to be compared with paint found on a victim's vehicle following an accident, or a sample of the suspect's and/or victim's blood submitted for comparison with a bloodstained shirt recovered as evidence). Reflected lightIncident illumination (cf. transmitted light) ReflectionWhen light strikes a surface and then leaves at the same angle. Angle in=angle out. The production of an image by or as if by a mirror. Relative fluorescence unit (RFU)a unit of measurement used in electrophoreses methods employing fluorescence detection. Fluorescence is detected on the CCD array as the labeled fragments, separated in the capillary by electrophoresis, and excited by the laser, pass the detection window. The software interprets the results, calculating the size or quantity of the fragments from the fluorescence intensity at each data point. RefractionThe deflection from a straight path undergone by a light ray or energy wave in passing obliquely from one medium (as air) into another (as glass) in which its velocity is different, or the action of distorting an image by viewing through a medium. Representative SampleA collection of hairs from a specific body area that encompasses the characteristics expressed in an individual's hair. ResolutionA measurement of how well the smallest details of an image can be discerned. The process or capability of making distinguishable the individual parts of an object, closely adjacent optical images, or sources of light. Restriction enzymeA protein harnessed from bacteria that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Restriction fragment length polymorphism - Variation in the length of a stretch of DNA; abbreviated RFLP.
RootThe root is the structure at the proximal end of a hair. S
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Top Sanger SequencingA widely used method of determining the order of bases in DNA. SarkosylAlso known as sodium lauroylsarcosine. A detergent used in DNA extraction. ScalesScales are plate-like structures composed of keratin that overlap to form the cuticle. SDISState DNA Index System containing the state-level DNA records uploaded from local laboratory sites within the state. SDIS is the state's repository of DNA identification records and is under the control of state authorities. The SDIS laboratory serves as the central point of contact for access to the National DNA Index System (NDIS). The DNA Analysis Unit I (DNAUI) serves as the SDIS laboratory for the FBI. SemenThe fluid (ejaculate) that is released through the penis during orgasm. Semen is made up of sperm from the testicles and other fluid from other sex glands. Sequence (or site) heteroplasmyPresence of mtDNA molecules that have different nucleotides at the same address. SequencingDetermination of the order of base sequences in a DNA molecule. ShaftThe portion of a hair between the root and the tip. Short Tandem Repeat (STR) typingDNA analysis method which targets regions on the chromosome which contain multiple copies of an identical DNA sequence in succession. Short Tandem Repeats (STR)Multiple copies of a short identical DNA sequence arranged in direct succession in particular regions of chromosomes. ShoulderingAn asymmetrical cross-section. Signal to Noise RatioA measure of signal strength relative to background noise. SimilarOf the same substance or structure throughout; homogeneous; having a marked resemblance or likeness; of a like nature or kind. Simple Sequence Repeats (SSR)A sequence consisting largely of a tandem repeat of a specific k-mer (such as (CA)15). Many SSRs are polymorphic and have been widely used in genetic mapping. SINE (Short INterspersed Element)A type of small dispersed repetitive DNA sequence (e.g. Alu family in the human genome) found throughout a eukaryotic genome. Single Nucleotide Polymorphisms (SNPs)DNA sequence variations that occur at a single nucleotide (A,T,C,or G). Single source profileA DNA profile where only one individual has contributed biologic material. Single-use EquipmentItems that will be used only once to collect evidence, such as biological samples, then discarded to minimize contamination (e.g., tweezers, scalpel blades, droppers). Slot BlotA technique for measuring the amount DNA or RNA. Samples are placed onto a hybridization membrane, fixed, and hybridized with a probe. Visualization techniques include use of a radioactive probe, chemiluminescence, or colorimetric based systems. The concentration of the samples is determined by comparing to standards of known concentrations. Sodium Dodecyl Sulfate (SDS)Also known as sodium lauryl sulfate (SLS). A detergent used in DNA extraction. SomaticReferring to an area of the body. SpectrophotometryThe determination of the structure or quantity of substances by measuring their capacity to absorb light of various wavelengths. SpermidinePolyamines originally isolated from semen and can inhibit PCR. Found in ribosomes and living tissues. SperminePolyamines originally isolated from semen and can inhibit PCR. Found in ribosomes and living tissues. Standard Operation Procedures (SOP)A prescribed procedure to be followed routinely. State (SDIS)State DNA Index System containing the state-level DNA records uploaded from local laboratory sites within the state. SDIS is the state's repository of DNA identification records and is under the control of state authorities. The SDIS laboratory serves as the central point of contact for access to NDIS. The DNA Analysis Unit I (DNAUI) serves as the SDIS laboratory for the FBI. Stochastic effectsBeing or having a random variable. Stutter
A minor band or peak appearing one repeat unit smaller than a primary STR (short tandem repeat) allele. Occasionally, the repeat unit is larger than the primary allele.
SubstrateAny background material upon which biological sample has been deposited (e.g., clothing, glass, wood, upholstery). SupernatantLiquid portion remaining after centrifugation or precipitation of a sample. SWGDAMScientific Working Group of DNA Analysis and Methods, formerly called TWGDAM (Technical Working Group on DNA Analysis and Methods). T
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Top Tannic AcidA naturally occurring compound used for tanning animal hides into leather. A known PCR inhibitor. Taq PolymeraseA heat-stable DNA polymerase isolated from the bacterium Thermus aquaticus, used in PCR. TE BufferA commonly used buffer in Molecular Biology, especially in procedures involving DNA. It is called "TE" buffer because it contains Tris and EDTA. TelogenThe last phase of the hair growth cycle when the hair root becomes a bulbous shaped root. Terminal hairLong, coarse, generally pigmented hairs, sometimes with medullation, representing the final state of differentiation of human hair. (cf. vellus, lanugo) Thermal CyclerAn instrument used to perform the polymerase chain reaction (PCR). Theta CorrectionA theta adjustment is a mathematical correction applied to a frequency calculation when both alleles at a locus are the same (known as a homozygous state). It is not applied when alleles are different at a locus (known as a heterozygous state). This correction adjusts the frequency slightly upwards to account for the presence of subpopulations in a general population database that might otherwise cause the genotype frequency to be underestimated at that locus. Third Party Defense MotionA motion filed by the prosecution to preclude the defense from asserting that DNA evidence is derived from a third party, possibly a relative of the accused. ThresholdThe point that must be exceeded to begin producing a given effect or result or to elicit a response. Threshold valueA relative fluorescent unit (RFU) value that must be exceeded to make an allele call. This value will vary among laboratories. TipThe most distal end of a hair's shaft. Trace evidencePhysical evidence that results from the transfer of small quantities of materials (e.g., hair, textile fibers, paint chips, glass fragments, gunshot residue particles). TranslucentAllowing the passage of light, yet diffusing it so as not to render bodies lying beyond clearly visible; semi-transparent. Transmitted lightIllumination which passes through a medium. TransparentHaving the property of transmitting light, so as to render bodies lying beyond completely visible. TrichologyThe study of the structure, functions, and diseases of the hair. TrichonodosisA condition characterized by apparent or actual knotting of the hair. TrichoptilosisA disease condition characterized by longitudinal splitting or fraying of the hair shaft. Trichorrhexis InvaginatiA genetic disease characterized by a segment of bulbous, dilated hair being enfolded into a concave hair terminal, recalling the appearance of a bamboo node. If the hair breaks at the bulbous end, the hair has a "golf tee cup" end. Trichorrhexis NodosaA condition characterized by the formation of nodes, and in extreme cases, the hair is weaker at the node and is subject to breakage. TrichoschisisA condition characterized by brittle hair with a transverse crack or a clean break. TrisAn abbreviation for tris (hydroxymethyl)methylamine, also known as tris(hydroxymethyl)aminomethane. It is widely used in biochemistry as a buffer salt. U
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Top UbiquitousExisting or being everywhere, widespread UndulatedChanges in diameter along the length of the hair shaft that result from changes in cross-sectional area. This can give the hair a wavy appearance. UninterpretableResults which might be reported by the laboratory when alleles can not be interpreted. Upper Bound Frequency Estimates
an estimate of the percentage of individuals who could be potential contributors of a mtDNA profile. UV light sourceUse of an ultraviolet light source to enhance or visualize potential items of evidence (fluids, fingerprints, clothing fibers, etc.). The light will cause possible biological stains to change color or fluoresce, assisting in the location process. V
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Top ValidationThe process of extensive and rigorous evaluation of DNA methods before acceptance for routine use. Variable Number of Tandem Repeats (VNTRs)Repeating units of a DNA sequence; a class of RFLPs (restriction fragment length polymorphism); abbreviated VNTR. VarianceA measure of the spread of a distribution about its average value. VariantA dissimilarity in the commonly occuring sequence of a gene. VellusShort, fine, unmedullated hairs spread more or less uniformly over the body. 4 (Harding and Rogers, 1999). Virtual ImageAn image (as seen in a plane mirror) formed of points from which divergent rays (as of light) seem to emanate without actually doing so. It does not exist physically. W
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Top Walk-throughAn initial assessment conducted by carefully walking through the scene to evaluate the situation, identify potential evidence, and determine resources required. It can also be a final survey conducted to ensure the scene has been effectively and completely processed. WavedA hair shaft form with curvature that changes its direction to produce a sinuous wave form and does not curve back upon itself to form a circle. Working distanceDistance between the front vertex of a lens and the object. Y
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Top Y-STR
short tandem repeats located on the Y chromosome.