ISO/IEC 19794-14:2022
(Main)Information technology — Biometric data interchange formats — Part 14: DNA data
Information technology — Biometric data interchange formats — Part 14: DNA data
This document specifies a data interchange format for the exchange of deoxyribonucleic acid (DNA) data for person identification or verification technologies that utilize human DNA. Consideration of laboratory procedures is out of scope of this document. This document provides the ability for DNA profile data to be exchanged and used for comparison (subject to privacy regulations) with DNA profile data produced by any other system that is based on a compatible DNA profiling technique and where the data format conforms to this document. This document is intended to cover current forensic DNA profiling or typing techniques that are based on short tandem repeats (STRs), including STRs on the X chromosome (X-STRs) the Y chromosome (Y-STRs), as well as mitochondrial DNA. A single DNA profile for a subject can contain data resulting from more than one of these different DNA techniques. This document enables data from multiple DNA techniques to be presented in a single DNA profile for a given subject. This document has been prepared in light of ongoing efforts to reduce human involvement in the processing (enrolment and comparison) of DNA. In anticipation of the data format requirements for automated DNA techniques, this document describes a format for both processed and raw (electrophoretic) DNA data. A normative XML schema definition (XSD) is provided in Clause A.1 for the syntax of DNA data XML documents. In Clause A.2, there is a sample DNA data XML document. This document is not intended for any other purposes than exchange of DNA for biometric verification and identification of individuals. In particular, it is not intended for the exchange of medical and other health-related information. This document also specifies elements of conformance testing methodology, test assertions and test procedures as applicable to this document. It establishes test assertions pertaining to the structure of the DNA data format (Type A Level 1 as defined in ISO/IEC 19794-1:2011/Amd. 1:2013) and test assertions pertaining to internal consistency of the values contained within each field (Type A,ind Level 2 as defined in ISO/IEC 19794-1:2011/Amd. 1:2013). This document also specifies test assertions pertaining to the content of DNA data XML documents (Level 3 as defined in ISO/IEC 19794-1:2011/Amd. 1:2013). The successful completion of Level 1 and Level 2 is a prerequisite for carrying out the tests at Level 3. The conformance testing methodology specified in this document does not establish: — tests of other characteristics of biometric products or other types of testing of biometric products (e.g. acceptance, performance, robustness, security); — tests of systems not claimed to conform to the requirements of this document.
Technologies de l'information — Formats d'échange de données biométriques — Partie 14: Données ADN
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 19794-14
Second edition
2022-10
Information technology — Biometric
data interchange formats —
Part 14:
DNA data
Technologies de l'information — Formats d'échange de données
biométriques —
Partie 14: Données ADN
Reference number
© ISO/IEC 2022
© ISO/IEC 2022
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ii
© ISO/IEC 2022 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 Terms related to basic DNA concepts . 2
3.2 Terms related to DNA profiling. 4
3.3 Terms related to DNA databases . 5
3.4 Terms related to DNA profile comparison and interpretation of results . 6
4 Abbreviated terms . 8
5 Conformance . 9
6 DNA data format specification . 9
6.1 Overview . 9
6.2 Data conventions . 10
6.2.1 Unknown field value . 10
6.2.2 DNA data handlings . 11
6.3 Content of the DNA XML schema . 15
6.3.1 Overview . 15
6.3.2 General header . 15
6.3.3 Representations . 18
6.3.4 Pedigrees . 35
7 Registered format type identifier .39
Annex A (normative) DNA XML schema definition and sample encoding .40
Annex B (normative) Conformance testing methodology .59
Annex C (informative) DNA kit identifiers .64
Annex D (informative) DNA loci .70
Annex E (informative) Kinship interoperability tests — Pedigree test cases .76
Annex F (informative) Additional interoperability tests . 107
Annex G (informative) DNA loci for identification purposes . 132
Bibliography .134
iii
© ISO/IEC 2022 – All rights reserved
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of document should be noted. This document was drafted in
accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or
www.iec.ch/members_experts/refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC
list of patent declarations received (see https://patents.iec.ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 37, Biometrics.
This second edition cancels and replaces the first edition (ISO/IEC 19794-14:2013), which has been
technically revised. It also incorporates the Amendment ISO/IEC 19794-14:2013/Amd. 1:2016.
The main changes are as follows:
— Clause 6 and Annex A have been technically revised to enable the standardized interchange of DNA
profile search results;
— Annex B has been technically revised to reflect the revised data interchange format;
— New Annexes E, F and G have been added.
A list of all parts in the ISO/IEC 19794 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
iv
© ISO/IEC 2022 – All rights reserved
Introduction
Forensic molecular genetics has evolved from a rapidly developing field with changing technologies into
a highly recognized and generally accepted forensic science. Forensic genetics using deoxyribonucleic
acid (DNA) profiling comprises a number of important applications. Examples are the investigation
of biological stains to obtain evidence for the presence of an alleged perpetrator at a crime scene by
comparing the genetic profiles from crime scene samples of human origin, to those available at DNA
databases administered by law enforcement agencies. These also include the identification of unknown
corpses in the context of both natural death and crime, immigration, paternity testing and disaster
victim identification (DVI).
This document is based on DNA data from forensic DNA typing techniques that are commonly used,
namely short tandem repeat (STR) profiling and other DNA typing techniques that are standardized by
scientific bodies for the purpose of discriminating between individuals.
The purpose of this data interchange format is to enable the exchange of DNA data from different
systems, not to impose any constraints on the specific DNA typing system/technique to be used. Where
existing DNA data exchange formats have been referenced in the preparation of this document, these
formats are listed as references.
Standard profiling systems exploit the non-coding parts of DNA that are referred to as “junk DNA”. The
coding regions, which are richer in information pertaining to specific genetic traits of an individual, are
deliberately avoided in order to maintain the privacy and civil rights of the donor. In addition, national
data protection and privacy legislation can impose special security safeguards, such as (but not limited
to) encryption of data transfers and/or storage.
This document supports XML (Extensible Markup Language) encoding, to support a spectrum of user
requirements. Annex A specifies the schema against which XML-encoded DNA data XML documents
are required to validate. It also contains a sample DNA data XML document. Annex B addresses the
conformance testing methodology. Annex C lists some examples of DNA analysis kits. Annex D lists
the names of DNA loci. Annex E lists interoperability test data for kinship searching in the form of
pedigrees. In Annex F, there is a description of interoperability tests at Level 3 (semantics). By means of
the sample inclusion and comparison rules listed in Annex G, a target can be identified among a number
of candidates.
v
© ISO/IEC 2022 – All rights reserved
INTERNATIONAL STANDARD ISO/IEC 19794-14:2022(E)
Information technology — Biometric data interchange
formats —
Part 14:
DNA data
1 Scope
This document specifies a data interchange format for the exchange of deoxyribonucleic acid (DNA)
data for person identification or verification technologies that utilize human DNA. Consideration of
laboratory procedures is out of scope of this document.
This document provides the ability for DNA profile data to be exchanged and used for comparison
(subject to privacy regulations) with DNA profile data produced by any other system that is based on a
compatible DNA profiling technique and where the data format conforms to this document.
This document is intended to cover current forensic DNA profiling or typing techniques that are based
on short tandem repeats (STRs), including STRs on the X chromosome (X-STRs) the Y chromosome
(Y-STRs), as well as mitochondrial DNA. A single DNA profile for a subject can contain data resulting
from more than one of these different DNA techniques. This document enables data from multiple DNA
techniques to be presented in a single DNA profile for a given subject.
This document has been prepared in light of ongoing efforts to reduce human involvement in the
processing (enrolment and comparison) of DNA. In anticipation of the data format requirements
for automated DNA techniques, this document describes a format for both processed and raw
(electrophoretic) DNA data. A normative XML schema definition (XSD) is provided in Clause A.1 for the
syntax of DNA data XML documents. In Clause A.2, there is a sample DNA data XML document.
This document is not intended for any other purposes than exchange of DNA for biometric verification
and identification of individuals. In particular, it is not intended for the exchange of medical and other
health-related information.
This document also specifies elements of conformance testing methodology, test assertions and test
procedures as applicable to this document. It establishes test assertions pertaining to the structure
of the DNA data format (Type A Level 1 as defined in ISO/IEC 19794-1:2011/Amd. 1:2013) and test
assertions pertaining to internal consistency of the values contained within each field (Type A,ind
Level 2 as defined in ISO/IEC 19794-1:2011/Amd. 1:2013). This document also specifies test assertions
pertaining to the content of DNA data XML documents (Level 3 as defined in ISO/IEC 19794-1:2011/
Amd. 1:2013). The successful completion of Level 1 and Level 2 is a prerequisite for carrying out the
tests at Level 3.
The conformance testing methodology specified in this document does not establish:
— tests of other characteristics of biometric products or other types of testing of biometric products
(e.g. acceptance, performance, robustness, security);
— tests of systems not claimed to conform to the requirements of this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
© ISO/IEC 2022 – All rights reserved
ISO/IEC 2382-37, Information technology — Vocabulary — Part 37: Biometrics
ISO 3166-1, Codes for the representation of names of countries and their subdivisions — Part 1: Country
code
ISO 3166-2, Codes for the representation of names of countries and their subdivisions — Part 2: Country
subdivision code
ISO/IEC 19794-1:2011, Information technology — Biometric data interchange formats — Part 1:
Framework
ISO/IEC 19794-1:2011/Amd. 1:2013, Information technology — Biometric data interchange formats —
Part 1: Framework — Amendment 1: Conformance testing methodology
ISO/IEC 19794-1:2011/Amd. 2:2015, Information technology — Biometric data interchange formats —
Part 1: Framework — Amendment 2: Framework for XML encoding
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 2382-37 and
ISO/IEC 19794-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Terms related to basic DNA concepts
3.1.1
deoxyribonucleic acid
DNA
complex molecule found in virtually every cell in the body that carries the genetic information from one
generation to another
3.1.2
chromosome
structure within the cell that bears the genetic material as a linear strand of DNA
Note 1 to entry: In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. 22 of
rd
these pairs, called autosomes, look the same in both males and females. The 23 pair, the sex chromosomes,
differs between males and females. Sex chromosomes in males are different in size and are called X and Y. Sex
chromosones in females are identical in size and both are called X.
3.1.3
Y chromosome
organized structure of the DNA molecule containing male-specific DNA only
3.1.4
non-coding part of DNA
chromosome regions not genetically expressed, i.e. not known to provide for any functional properties
of an organism
3.1.5
locus
unique physical location on the DNA molecule
Note 1 to entry: The plural of locus is loci.
© ISO/IEC 2022 – All rights reserved
3.1.6
allele
member of two or more alternative forms of a DNA sequence found at a particular locus
3.1.7
tri-allelic pattern
locus that shows an occasional detection of three alleles in single-source samples
Note 1 to entry: Tri-allelic patterns can show unbalanced peak heights (Type I: The sum of heights of two of
the peaks is equal to the third) or balanced peak heights (Type II: The peaks of the three alleles are of a similar
height).
3.1.8
chimera
individual having two different sets of DNAs with the code to make two separate individuals
Note 1 to entry: Otherwise said, this is a single individual composed of cells with more than one distinct genotype.
3.1.9
homozygote
individual having the same (or indistinguishable) alleles at a particular locus due to the inheritance of
the same allele from each parent
Note 1 to entry: A heterozygote is an individual having two different alleles at a particular locus.
3.1.10
short tandem repeat
STR
short sequence of DNA that is repeated numerous times in direct succession
Note 1 to entry: The number of repeated units can vary widely between individuals and this high level of variation
makes STRs particularly useful for discriminating between individuals.
Note 2 to entry: STR analysis is one of the most useful methods in forensic genetics for comparing specific loci on
DNA from two or more samples.
3.1.11
autosomal STR
aSTR
STR region found only in autosomal chromosomes in the nucleus of the cell
3.1.12
X-STR
STR region found in female-specific DNA on the X chromosome only
3.1.13
Y-STR
STR region found in male-specific DNA on the Y chromosome only
Note 1 to entry: Y-STR can be used to trace paternal lineages as it is male specific and only inherited from fathers
to their sons.
3.1.14
mitochondrial DNA
mtDNA
small circular DNA molecules located in structures used to provide energy to the cell (mitochondria)
Note 1 to entry: Mitochondria often are called the powerhouse of the cell. Their small size and abundant nature
make them particularly useful when examining small or much-damaged biological material.
Note 2 to entry: The mitochondria, and thus mitochondrial DNA, are passed only from mother to offspring
through the egg cell. It can be used to trace maternal lineages as it is only inherited from one’s mother.
© ISO/IEC 2022 – All rights reserved
3.2 Terms related to DNA profiling
3.2.1
DNA profiling
DNA typing
technique used by scientists to discriminate between individuals by examining variations in their DNA
3.2.2
allelic ladder
artificial mixture of the common alleles present in the human population for a particular STR marker
that is used during a DNA profiling process (capillary electrophoresis) in parallel with the sample of
interest for accurate allele call determination
3.2.3
electropherogram
graphic representation of results of a DNA profiling process (capillary electrophoresis) with the X axis
displaying the observed alleles and the Y axis recording the relative amount of DNA detected based on
the relative fluorescent unit collected during analysis
Note 1 to entry: Electropherograms can be transmitted as image files if this is needed from partner DNA
laboratories for validation of DNA profiles.
3.2.4
DNA profile
set of alphanumeric values describing the molecular structure at a group of loci identified in an
individual’s DNA
Note 1 to entry: A DNA profile is referred to as DNA fingerprint, DNA type or genetic fingerprint in other
documents.
3.2.5
forensic DNA profile
DNA profile that represents a set of identification characteristics from non-coding parts of an analysed
human DNA sample
3.2.6
mixed stain
biological stain that contains body fluids or tissues from more than one individual
EXAMPLE Contaminated sample, DNA sample taken from a swabbing of a surface of a drinking vessel or
cigarette that has been shared
3.2.7
mixed DNA profile
DNA profile generated from a mixed stain
Note 1 to entry: In many cases where a sample consists of a stain or body fluid deposits of multiple individuals,
the mixed DNA cannot be isolated when the sample is acquired.
Note 2 to entry: Where the profile of one or more of the mixed DNA sample contributors is known, the mixture
can be separated into its contributing DNA profiles. One of the processes is called mixture deconvolution. This
involves analysing the mixture DNA profile and exploiting the probabilistic and genetic hereditary properties of
DNA to separate the profiles.
3.2.8
fully designated locus
locus of which all positions are reliably typed
Note 1 to entry: The locus status of a fully designated locus is “Normal”.
© ISO/IEC 2022 – All rights reserved
3.2.9
partial locus
locus at which not all the alleles show up
3.2.10
partial DNA profile
DNA profile with partial loci or in which not all the loci targeted show up
EXAMPLE If 13 loci were targeted and only 9 could be reported, that would be termed a partial DNA profile.
Note 1 to entry: A DNA profile can be partial at the profile level, partial at the locus level or both.
3.2.11
DNA mobile processing unit
fully-functional DNA laboratory that is mobile
3.2.12
rapid DNA instrument
self-contained device that carries out a fully-automated DNA analysis of a DNA sample
3.3 Terms related to DNA databases
3.3.1
Interpol DNA Database
central forensic DNA database to which all Interpol member states can submit forensic DNA profiles
of unsolved crimes, criminals, missing persons or unknown human remains through their National
Interpol Bureaus, both with classic DNA profile storage or search requests and through online DNA
profile data transfers from their national DNA databases for automated searching
Note 1 to entry: Interpol runs also a separate Missing Persons DNA database (I-Familia) using family DNA
comparison to identify unknown human remains.
3.3.2
Interpol Standard Set of Loci
ISSOL
set of STR loci defined by the Interpol DNA Monitoring Expert Group, which recommends for use as
common DNA loci for forensic DNA analyses in all forensic DNA kits and with minimum loading criteria
to input a profile in the Interpol DNA Database to enable worldwide comparability of STR profiles and
thus uniform crime fighting worldwide by usage of forensic DNA technology
3.3.3
Interpol DNA Monitoring Expert Group
advisory board with senior experts from Interpol member states for creation of recommendations on
the use of DNA in criminal and missing person investigations including creation of Interpol DNA profile
interchange standards and forms as well as rules for the Interpol DNA Database
3.3.4
Prüm DNA Database Network
decentralized database network system originally developed by some EU member states, in which
biometric data, such as forensic DNA profiles, can be compared online and in real time with DNA profile
search queries between the Prüm partner states
Note 1 to entry: The Prüm network has not only been implemented in a legally binding manner by all EU member
states through EU legal acts but has also been extended through bilateral and multilateral state agreements
to become a globally functioning Prüm data network system for biometric online data exchange (e.g. Western
Balkan states).
© ISO/IEC 2022 – All rights reserved
3.3.5
European Standard Set of loci
ESS
set of STR loci defined by the ENFSI DNA Working Group which is recommended for use as minimum
and common DNA loci for forensic DNA analyses in all forensic DNA kits and with minimum loading
criteria to input a profile in the Prüm DNA Database Network to enable European comparability of STR
profiles
3.3.6
ENFSI DNA Working Group
working group that supports the aims and objectives of ENFSI in the area of DNA casework analysis
including definition of quality and STR loci standards for possible international forensic DNA
cooperation
3.3.7
request
message containing one or more DNA profiles to be searched or stored or updated in or removed from
a DNA profile database
3.3.8
response
message containing one or more answers depending on request message
Note 1 to entry: Match results, non-match results, error messages, notification of storage or deletion or update.
3.4 Terms related to DNA profile comparison and interpretation of results
3.4.1
power of discrimination
potential power of a genetic marker or set of markers to differentiate between any two individuals
chosen at random
3.4.2
reference DNA profile
DNA profile of an identified person
3.4.3
target DNA profile
DNA profile contained in a request for comparison against a DNA profile database
3.4.4
exact match
outcome of a DNA search engine when all allele values of the compared loci are the same in two DNA
profiles
3.4.5
rare allele value
allele value present in low frequency at a specific population and, therefore, much more significant than
other alleles for identification purposes
3.4.6
wildcard
symbol substituting a rare allele value at a locus and matching any value at the corresponding locus in
a DNA profile
Note 1 to entry: An asterisk is commonly used as a wildcard.
Note 2 to entry: Two different patterns can match in a wildcard search.
© ISO/IEC 2022 – All rights reserved
3.4.7
microvariant
allele containing an incomplete repeat unit or appearing to have values beyond a specified range
Note 1 to entry: Many STR markers are composed of a specific sequence of four nucleotides (called nucleus, core
or repeat unit). The sequence of nucleotides is repeated in tandem a number of times which varies. When one of
the repeat units is incomplete (e.g. shows three nucleotides instead of four), the allele is called a microvariant.
3.4.8
mismatch
outcome of a DNA search engine when only one difference, which involves a wildcard or a microvariant,
is found in a comparison of two DNA profiles
3.4.9
near match
outcome of a DNA search engine when only one of all allele values of the compared loci is different in
two DNA profiles
3.4.10
match
outcome of a DNA search engine that is either an exact match, a near match or a mismatch
3.4.11
non-match
outcome of a DNA search engine other than exact match, near match or mismatch
3.4.12
match quality
level of agreement between two DNA profiles
EXAMPLE The following match quality levels can be distinguished:
— Q1: exact match
— Q2: near match (only one potential difference involving a wildcard)
— Q3: near match (only one difference, which involves a microvariant)
— Q4: mismatch (only one difference other than wildcards or microvariants)
Note 1 to entry: Some DNA search engines use a likelihood ratio to quantify the match quality.
3.4.13
match count
number of identical loci found in comparison of two DNA profiles
3.4.14
adventitious match
match that happens by chance instead of having the same source or being linked by kinship
Note 1 to entry: In the case of DNA testing, not having enough distinguished characteristics (e.g. due to a partial
DNA profile) can lead to adventitious matches. DNA search engine matches therefore always need forensic
verification/validation for possible detection of adventitious matches.
3.4.15
candidate
DNA profile found in a DNA profile database satisfying the defined matching criteria against the target
DNA profile
© ISO/IEC 2022 – All rights reserved
3.4.16
hit
candidate confirmed by a DNA examiner
Note 1 to entry: A "no-hit" is a candidate rebutted by a DNA examiner, for example, detected adventitious match.
Note 2 to entry: Validation is required to be carried out in line with forensic quality management requirements
(e.g. accreditation standards).
4 Abbreviated terms
AABB American Association of Blood Banks
BDB biometric data block
BIR biometric information record
CBEFF Common Biometric Exchange Formats Framework
CE capillary electrophoresis
CODIS Combined DNA Index System
CRS Cambridge Reference Sequence
DLR DNA loci reference
DVI disaster victim identification
ENFSI European Network of Forensic Science Institutes
FSA fragment sequence analysis
GLP Good Laboratory Practice
GPS global positioning system
HV hypervariable regions of mitochondrial DNA
ILAC International Laboratory Accreditation Cooperation
ISFG International Society of Forensic Genetics
IUPAC International Union of Pure and Applied Chemistry
IUT implementation under test
ICS implementation conformance statement
NA not available
NGS next-generation sequencing
NIST National Institute of Standards and Technology
ORI originating agency identifier
PCR polymerase chain reaction
POC point of contact
© ISO/IEC 2022 – All rights reserved
QA quality assurance
rCRS revised Cambridge Reference Sequence
RDBMS relational database management system
SNP single-nucleotide polymorphism
SQL Structured Query Language
UTC Coordinated Universal Time
WGS World Geodetic System
XML Extensible Markup Language
XSD XML schema definition
5 Conformance
An XML document conforms to this document if it satisfies the format requirements with respect to its
structure, relations among its fields and relations between its fields and the underlying input that are
specified within Clause 6 and Clause A.1.
Biometric data interchange format conformance tests conform to this document if they satisfy all the
normative requirements set forth in Annex B.
Implementations are not required to conform to all possible aspects of this document, but only to those
that are claimed to be supported by the implementation in an implementation conformance statement
(ICS), filled out in accordance with ISO/IEC 19794-1:2011/Amd. 1:2013 and Table B.1 of this document.
6 DNA data format specification
6.1 Overview
XML documents encoding DNA data shall validate against the XML schema definition in Clause A.1.
In conformance to ISO/IEC 19794-1, a DNA data XML document may or may not be embedded in
an appropriate CBEFF (Common Biometric Exchange Formats Framework) compliant biometric
information record (BIR).
There are two kinds of fields (in XML also known as elements): simple and combined. A simple field
contains only one simple data object, and a combined field contains one or more fields that can be simple
or combined. Simple and combined fields are implemented by the XML mechanisms “simple type” and
“complex type”, respectively.
The structure of a DNA data XML document is depicted in Figure 1.
© ISO/IEC 2022 – All rights reserved
Key
combined
simple
optional
Figure 1 — DNA data format
6.2 Data conventions
6.2.1 Unknown field value
For mandatory fields of unrestricted string type, a value “Unknown” shall be used to denote that the
information to be encoded in this field is not yet determined.
© ISO/IEC 2022 – All rights reserved
6.2.2 DNA data handlings
6.2.2.1 Mixed DNA profiles
For mixed profiles, the following data fields should be exchanged:
— Allele calls
— Electropherogram image
— Fragment sequence analysis (FSA) data, (e.g. fsa, hid files)
— Deconvoluted single source profiles with confidence intervals
— Algorithm/tool used to deconvolute
Deconvolution should not be carried out by hand. Currently there are sufficiently available software
[1] [2]
tools to infer contributing profiles to a DNA mixture (e.g. EuroForMix, CaseSolver, which are free).
Free software exists to enable the development of searches for mixtures of more than two contributors
(up to five), for specific cases, using the user's own database outside the Combined DNA Index System
[3]
(CODIS).
6.2.2.2 Single source DNA profile with more than two allele values
More than two alleles can appear:
— in only one locus (tri-allelic patterns in single source samples);
— in several loci when the profile comes from DNA mixture (more than one contributor).
Two types of tri-allelic patterns exist (see Figure 2):
— type I (different peak heights) is due to somatic mutation of one allele that occurs during an
individual’s development. These patterns are characterized by uneven peak heights for the two
variants of the affected allele that sum to the height of a non-mutated allele.
— type II (same peak heights) is mainly due to a localized duplication event or chromosomal aneuploidy
(e.g. trisomy, three chromosomes instead of two chromosomes in a pair). These patterns are usually
characterized by the appearance of peaks of equal height.
For the incidence of tri-allelic patterns, References [4] and [5] can be consulted.
NOTE The incidence of tri-allelic patterns type II is different in different loci.
EXAMPLE Loci D21S11 and D18S51 show more tri-allelic patterns than other loci due to trisomy in
chromosomes 21 and 18 respectively; Penta_D is also located on chromosome 21; TPOX show tri-allelic patterns
in African populations (2,4 %), with the extra allele almost always being allele 10 which is really located on
[6]
X-chromosomes.
© ISO/IEC 2022 – All rights reserved
Key
A type I
B type II
Figure 2 — Types of tri-allelic patterns
In addition to sending data in the most precise form known, there are several alternatives for exporting
tri-allelic patterns.
1) First allele: If three alleles are provided for one locus, the first allele will be accepted and the
remaining two alleles will be automatically converted for the export to a wildcard (*) and searched
against all. Type I in Figure 2 would be exported as “9; *” and Type II as “8; *”.
2) Any allele: One of the alleles in a locus, independent of its position, will be accepted in the case
of non-mutated alleles. In this case, the other two allele values will be substituted by a wildcard.
However, it is not always possible to verify which is the non-mutated allele. Type I in Figure 2 would
be exported as “13; *” and Type II as “8; *”.
While in Type I patterns the non-mutated allele can be inferred, this is not the case for Type II patterns.
Therefore, option 1) proves more effective for use in practice.
If the DNA profile is a mixture, then use the recommendations for DNA data handling for mixed DNA
profiles; see 6.2.2.1.
The parties involved in an automatic procedure on DNA data exchange should follow the following
recommendations:
— generally, DNA profiles should be transmitted for comparison with their fully-designated allele
values if they are fully available, as well as tri-allelic and/or rare off-ladder allele values.
— if DNA profiles in national data storage components store rare allele values as wild cards (*), they
should be transmitted for comparison as stored in the national data storage components.
6.2.2.3 DNA profile with homozygosis
In case of a homozygote, both alleles should be given the same value in a DNA database according to the
related genotype.
There are two cases to be differentiated:
— Only one allele available: a partial locus with an allelic dropout;
— Homozygote: same value for both alleles.
Allelic drop-out can result from various reasons. In evidential samples, degradation or very small
amounts of DNA in the sample can lead to allelic dropout. Stochastic effects during the polymerase
chain reaction (PCR) can cause the template DNA of some of the alleles to be insufficiently present for
copying during the first cycles.
© ISO/IEC 2022 – All rights reserved
Reference samples of good quality can also show an apparent allelic drop-out. The reasons are very
different from the ones described in the previous paragraph. In this case, a mutation in the primer
binding zone can cause the lack of amplification of one of the two alleles of a locus. Usually, if the sample
is amplified by using a different kit (i.e. with different primers), both alleles can be detected.
There should also be a designation that the profile is partial as partial DNA profiles can have bias,
limited information or drop-in/out events present. These should be reviewed with caution and both of
the parties (submitting and receiving) should know there is a partial DNA profile for review.
The combination of metadata fields and allele calls in this document allows exchanging of homozygous
profiles and profiles with only one allele due to null allele or allele drop-out.
EXAMPLE 1 Only one allele available – locus with one reliably typed allele and a potential null/silent allele.
TPOX
SilentAllele
O.P. Wilson
Autosomal
Equal
8
EXAMPLE 2 Only one allele available – locus with one reliably typed allele and a suspected allele dropout.
D10S1248
Partial
O.P. Wilson
Autosomal
Equal
13
EXAMPLE 3 Only one allele available – locus with somewhat uncertain allele call.
D13S317
NotDefinitive
O.P. Wilson
Autosomal
Equal
9
EXAMPLE 4 Homozygote – same value for both alleles in the database.
CSF1PO
Normal
O.P. Wilson
Autosomal
© ISO/IEC 2022 – All rights reserved
Equal
10
Moreover, the receiving party can view/examine the raw data (electropherogram image and .fsa file in
the XML document) to perform additional analysis as needed.
6.2.2.4 DNA profile with rare allele values
Rare allele values can be very effective for identification purposes, if available. As indicated in 6.2.2.2,
DNA profiles with their fully-designated allele values should be transmitted for comparison if they are
available. However, different national DNA databases differ in the way rare allele values are recorded.
A wildcard, which substitutes a rare allele value and denotes any value, may be used when data is
[7]
exchanged for searching.
6.2.2.5 DNA profile with loci drop-out
Blank spaces exist in a partial DNA profile (a DNA profile for which complete typing results are not
obtained at all tested loci). This can be due to limited DNA template, DNA degradation, inhibition,
preferential amplification and/or stochastic effects.
A partial DNA profile should be left as it is, not supplemented by wildcards. Loci dropouts should be
handled in XML by using the profile partial indicator.
EXAMPLE The missing values in a profile from using GlobalFiler Express kit with D7S820 and D2S1338
missing can be exchanged in the following XML code example:
DataSubmissionAndSearch
U654321
BI
Unknown
Unknown
SingleSourceStain
UnidentifiedPerson
Unknown
Male
Dead
false
D7S820 and D2S1338 yield no data.
STR
GlobalFiler Express
IlacGuild19Accreditation
LabCertificationValue>
Nuclear
true
D3S1358
© ISO/IEC 2022 – All rights reserved
Normal
Unknown
...
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