prEN ISO 25379-2

• Abstract:

  This document specifies requirements and gives recommendations for next generation sequencing (NGS) workflows. This document covers the pre-examination processes, human RNA isolation, sequencing library preparation, sequencing, sequence analysis and reporting of the examination of sequences for diagnostic purposes from isolated RNA from, e.g. formalin-fixed and paraffin embedded tissues, fresh frozen tissues, fine needle aspirates (FNA), whole blood, circulating tumour cells (CTCs), exosomes and other extracellular vesicles, and circulating cell free RNA from plasma. NOTE 1 Typical applications include, but are not limited to, NGS for oncology and clinical genetics, certain single-cell analyses. This document is addressing in vitro diagnostic examinations including laboratory developed tests and is applicable to medical laboratories, molecular pathology laboratories and molecular genetic laboratories, in vitro diagnostic developers and manufacturers, biobanks as well as institutions and organizations performing biomedical research or sequencing services. This document is not applicable for in situ sequencing, forensic sequencing, sequencing of pathogens or microorganisms and microbiome analysis. NOTE 2 International, national or regional regulations or requirements or multiples of them can also apply to specific topics covered in this document.

• Status: Not Published
• Publication Date: 09-Apr-2028
• ICS: 11.100.10 - In vitro diagnostic test systems
• Technical Committee: CEN/TC 140 - In vitro diagnostic systems
• Drafting Committee: CEN/TC 140/WG 3 - Quality management in the medical laboratory
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 17-Sep-2026
• Due Date: 02-May-2026
• Completion Date: 17-Sep-2026
• Ref Project: oSIST prEN ISO 25379-2:2026 - In vitro diagnostic Next Generation Sequencing (NGS) workflows - Part 2: Human RNA examination (ISO/DIS 25379-2:2026)

• Revises: CEN/TS 17981-2:2023 - In vitro diagnostic Next Generation Sequencing (NGS) workflows - Part 2: Human RNA examination
• Effective Date: 19-Feb-2025

SLOVENSKI STANDARD
01-november-2026
In vitro diagnostični delovni postopki z uporabo sekvenciranja naslednje
generacije (NGS) - 2. del: Preiskava človeškega RNK (ISO/DIS 25379-2:2026)
In vitro diagnostic Next Generation Sequencing (NGS) workflows - Part 2: Human RNA
examination (ISO/DIS 25379-2:2026)
Next-Generation-Sequencing (NGS)-Arbeitsabläufe für die In-vitro-Diagnostik - Teil 2:
Untersuchung von menschlicher RNA (ISO/DIS 25379-2:2026)
Flux de travaux pour le diagnostic in vitro par séquençage de nouvelle génération (NGS)
- Partie 2: Examen de l'ARN humain (ISO/DIS 25379-2:2026)
Ta slovenski standard je istoveten z: prEN ISO 25379-2
ICS:
11.100.10 Diagnostični preskusni In vitro diagnostic test
sistemi in vitro systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 25379-2
ISO/TC 212
In vitro diagnostic Next Generation
Secretariat: ANSI
Sequencing (NGS) workflows —
Voting begins on:
Part 2: 2026-09-16
Human RNA examination
Voting terminates on:
2026-12-09
Flux de travaux pour le diagnostic in vitro par séquençage de
nouvelle génération (NGS) —
Partie 2: Examen de l'ARN humain
ICS: 11.100.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 25379-2:2026(en)
DRAFT
ISO/DIS 25379-2:2026(en)
International
Standard
ISO/DIS 25379-2
ISO/TC 212
In vitro diagnostic Next Generation
Secretariat: ANSI
Sequencing (NGS) workflows —
Voting begins on:
Part 2:
2026-09-16
Human RNA examination
Voting terminates on:
2026-12-09
Flux de travaux pour le diagnostic in vitro par séquençage de
nouvelle génération (NGS) —
Partie 2: Examen de l'ARN humain
ICS: 11.100.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 25379-2:2026(en)
ii
ISO/DIS 25379-2:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General requirements .15
4.1 General . 15
4.2 Examination design.16
4.3 Examination development .21
4.4 Examination performance verification and validation .21
4.5 Technical examination performance characteristics . 29
5 Pre-examination processes for examination development .30
5.1 General . 30
5.2 Human RNA isolation .31
5.2.1 General .31
5.2.2 Isolation from formalin fixed and paraffin embedded (FFPE) tissue .31
5.2.3 Isolation from fresh frozen tissue .31
5.2.4 Isolation from fine needle aspirates (FNA) .31
5.2.5 Isolation from whole blood .31
5.2.6 Isolation of circulating cell free RNA from plasma .32
5.3 RNA sample quality and quantity evaluation .32
6 Examination processes for examination development .34
6.1 Sequencing library preparation for examination development . 34
6.1.1 General . 34
6.1.2 Sequencing library preparation steps . 34
6.1.3 RNA sequencing (RNA-Seq) .37
6.2 NGS equipment requirements and recommendations for examination development . 40
6.2.1 General . 40
6.2.2 Techniques . 40
6.2.3 Sequencing quality control .41
6.3 Data analysis requirements for examination development .41
6.4 Quality control (QC) requirements for examination development .42
6.4.1 General .42
6.4.2 RNA Sequencing .42
7 Requirements for the development of the examination reporting tool .43
7.1 General .43
7.2 Report attributes . 44
7.3 Report content . 44
8 Implementation of the in vitro diagnostic NGS workflow into routine practice .45
9 Reporting and interpretation of results .46
10 Quality assurance procedures .47
10.1 General .47
10.2 Performance monitoring, optimization of the examination and interlaboratory
comparison .47
Annex A (normative) in vitro diagnostic NGS workflow for single-cell analyses .48
Annex B (normative) Exemplary in vitro diagnostic NGS workflow for spatial transcriptomics.55
Annex C (informative) in vitro diagnostic NGS workflow scheme for the examination of RNA .56
Bibliography .58

iii
ISO/DIS 25379-2:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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 ISO documents 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
This document was prepared by Technical Committee ISO/TC 212, Medical laboratories and in vitro diagnostic
systems.
A list of all parts in the ISO 25379 series can be found on the ISO website.
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.

iv
ISO/DIS 25379-2:2026(en)
Introduction
Molecular in vitro diagnostics has enabled significant progress in medicine. Further progress is expected by
new technologies analysing profiles of nucleic acids, proteins, and metabolites in human tissues and body
fluids. Next Generation Sequencing (NGS) takes a prominent place in the series of molecular techniques used
for diagnostics. It facilitates sequence analysis of nucleic acids that can result in precise information for
diagnosis and progression of diseases.
The NGS technique, however, has a very complex workflow that contains many steps. The target nucleic acids
can originate from different sources, e.g. tissues, blood, and body fluids. The profiles of the isolated RNA can
change during specimen collection, transport, storage and processing (e.g. formalin fixation) making the
outcome from diagnostics or research unreliable or even impossible because the subsequent analytical assay
will not determine the situation in the patient but an artificial profile generated during the pre-examination
process. The available material can be small, the cells in a tissue can be dispersed heterogeneously (e.g.
ratio of tumour to normal), the target nucleic acids can be circulating in blood or body fluids free of cells
or in circulating cells (e.g. circulating tumour cells (CTCs)). For a successful and reliable sequencing result,
a suitable strategy needs to be chosen for every case depending on the available material and disease
conditions. Therefore, the NGS workflow can differ from case to case, and the NGS workflow steps need to be
carefully considered and chosen to get a sound and reliable result to determine the best available treatment
for the patient. In addition, sequencing platforms can differ in their technique (e.g. detection of a change
in a current or fluorescence) and approach (e.g. whole transcriptome, panels, short-read sequencing, long-
read sequencing) for sequence assessment. The bioinformatics analysis can differ in approach and ability to
detect non-conformities and unreliable sequencing results. To enable such capabilities, NGS metadata needs
to be collected during all workflow steps from the patient to the reporting. In addition, controls and added
controls need to be analysed properly. This way non-conformities or detected unreliabilities can be reported
to the patient and the treating physician. The reporting of diagnostic NGS results can differ in clarity and
depth, which can lead to different interpretations.
Standardization of the entire NGS workflow from specimen collection to the reporting of the results to the
patient and the treating physician is needed for the development of reliable NGS examinations.
This document draws upon previous work to standardize the steps for NGS examinations from tissues, blood
and body fluids in what is referred to as the pre-examination phase (sample collection), the examination
phase (library preparation, sequencing), and the post-examination phase (analysis and reporting).
In this document, the following verbal forms are used:
— “shall” indicates a requirement;
— “should” indicates a recommendation;
— “may” indicates a permission;
— “can” indicates a possibility or a capability.

v
DRAFT International Standard ISO/DIS 25379-2:2026(en)
In vitro diagnostic Next Generation Sequencing (NGS)
workflows —
Part 2:
Human RNA examination
1 Scope
This document specifies requirements and gives recommendations for next generation sequencing (NGS)
workflows for in vitro diagnostics and biomedical research. This document covers the pre-examination
processes including human RNA isolation, sequencing library preparation, sequencing, sequence analysis
and reporting of the examined sequences for diagnostic purposes from isolated RNA from, e.g. formalin-fixed
and paraffin embedded tissues, fresh frozen tissues, fine needle aspirates (FNA), whole blood, circulating
tumour cells (CTCs), exosomes and other extracellular vesicles, and circulating cell free RNA from plasma.
NOTE 1 Typical applications include, but are not limited to, NGS for oncology and clinical genetics, certain single-
cell analyses.
This document addresses in vitro diagnostic examinations including laboratory developed examinations and
is applicable to medical laboratories, molecular pathology laboratories and molecular genetic laboratories,
in vitro diagnostic developers and manufacturers, biobanks as well as institutions and organizations
performing biomedical research or sequencing services.
This document is not applicable for in situ sequencing, forensic sequencing, sequencing of pathogens or
microorganisms and microbiome analysis.
NOTE 2 International, national or regional regulations or requirements or multiples of them can also apply to
specific topics covered in 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 7552-1, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes for
circulating tumor cells (CTCs) in venous whole blood — Part 1: Isolated RNA
ISO 18702, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes for
exosomes and other extracellular vesicles in venous whole blood — DNA, RNA and proteins
ISO 18703, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes for
venous whole blood — Isolated circulating cell free RNA from plasma
ISO 15189:2022, Medical laboratories — Requirements for quality and competence
ISO/IEC 17020:2012, Conformity assessment — Requirements for the operation of various types of bodies
performing inspection
ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories
ISO 20166-1, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes for
formalin-fixed and paraffin-embedded (FFPE) tissue — Part 1: Isolated RNA

ISO/DIS 25379-2:2026(en)
ISO 20184-1:2018, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes
for frozen tissue — Part 1: Isolated RNA
ISO 20186-1, Molecular in vitro diagnostic examinations — Specifications for pre-examination processes for
venous whole blood — Part 1: Isolated cellular RNA
ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules
ISO 20397-1:2022, Biotechnology — Massively parallel sequencing — Part 1: Nucleic acid and library preparation
ISO 20397-2, Biotechnology — Massively parallel sequencing — Part 2: Quality evaluation of sequencing data
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15189 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
aliquot
portion of a larger amount of homogenous material, assumed to be taken with negligible sampling error
Note 1 to entry: The term is usually applied to fluids. Tissues are heterogeneous and therefore cannot be aliquoted.
[1] [2] [3]
Note 2 to entry: The definition is derived from , , .
[SOURCE: ISO 20184-3:2021, 3.1, modified ─ Note 2 to entry was added.]
3.2
amplicon
specific DNA fragment produced by a DNA-amplification technology, such as the polymerase chain reaction
(PCR)
[SOURCE: ISO 13495:2013, 3.3.1]
3.3
analyte
component represented in the name of a measurable quantity
Note 1 to entry: The term “analyte”, or the name of a substance or compound, is not to be confused with the term
“measurand”, because analytes are not quantities.
EXAMPLE Amount of substance of glucose in plasma is a measurand (3.39), while glucose is the analyte.
[SOURCE: ISO 17511:2021, 3.1, modified — Note 1 and example were added]
3.4
analytical accuracy
closeness of the agreement between the result of an examination (3.21) and a true property value
Note 1 to entry: For NGS-based examinations, accuracy represents the degree of concordance (or agreement) of results
between a sequence obtained from the examination and the same sequence determined by a valid comparator method,
or between a reference sample run on an NGS-based examination and the high confidence sequence of the reference.
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified – Original notes were deleted, Note 1 to entry was added;
"analytical accuracy" replaces all old terms, "a measured quantity value" was replaced by "the result of an
examination" and "quantity value of a measurand" was replaced by "property value".]

ISO/DIS 25379-2:2026(en)
3.5
analytical sensitivity
sensitivity of a measurement procedure
quotient of the change in a measurement indication and the corresponding change in a value of a quantity
being measured
Note 1 to entry: The sensitivity of a measurement procedure (3.41) can depend on the value of the quantity being
measured.
Note 2 to entry: The change considered in the value of the quantity being measured only becomes useful compared
with the resolution.
Note 3 to entry: The analytical sensitivity of a measuring system is the slope of the calibration curve.
Note 4 to entry: Analytical sensitivity is often confused with positive percentage agreement (PPA), because similar
calculations are used for both the analytical sensitivity and the PPA. However, the term PPA instead of analytical
sensitivity is only used, if a reference method is not available or not used. The PPA represents merely an estimation of
the analytical sensitivity. PPA is applicable only to measurements of quantities that have the nature of a count.
[SOURCE: ISO/IEC Guide 99:2007, 4.12, modified — terms changed from "sensitivity of a measuring system
/sensitivity" changed to "analytical sensitivity/sensitivity of a measurement procedure"; "an indication of a
measuring system" replaced by "a measurement indication", "measuring system" replaced by "measurement
procedure" in Note 1; new Note 3 and Note 4 were added.]
3.6
analytical specificity
selectivity of a measurement procedure
capability of a measuring system, using a specified measurement procedure (3.41), to provide measurement
results for one or more measurands (3.39) which do not depend on each other nor on any other quantity in
the system undergoing measurement (3.40)
Note 1 to entry: Lack of analytical specificity is called analytical interference (see ISO 18113-1:2022, 3.2.2).
Note 2 to entry: Specificity of a measurement procedure (3.40) should not be confused with diagnostic specificity (see
ISO 18113-1:2022, 3.2.18).
Note 3 to entry: ISO/IEC Guide 99:2007 uses the term selectivity for this concept instead of specificity.
Note 4 to entry: Adapted from ISO/IEC Guide 99:2007, 4.13.
Note 5 to entry: Selectivity as used in metrology is a concept close to specificity as it is sometimes used in chemistry.
“Specificity” of measurements has some risk of ambiguity with “clinical/diagnostic specificity”.
Note 6 to entry: Analytical specificity is often confused with negative percentage agreement (NPA), because the same
calculations are used for both the analytical specificity and the NPA. However, the term NPA instead of analytical
specificity is only used, if a reference method is not available or is not used. The NPA represents merely an estimation
of the analytical specificity.
[SOURCE: ISO 18113-1:2022, 3.2.5, modified —Note 2 was deleted and 5 and 6 were added.]
3.7
bioinformatics pipeline
suite of different bioinformatics tools that process the NGS data
3.8
biomarker
molecular marker
detectable and/or quantifiable molecule or group of molecules used to indicate a biological condition, state,
identity or characteristic or an organism
[SOURCE: ISO 16577:2022, 3.4.28]

ISO/DIS 25379-2:2026(en)
3.9
circulating cell free RNA
ccfRNA
extracellular human RNA (3.65) present in blood and plasma
Note 1 to entry: ccfRNA includes RNA present in vesicles such as exosomes.
3.10
clinical accuracy
diagnostic accuracy
extent of agreement between the outcome of the examination (3.21) and the target clinical condition
3.11
clinical performance
ability of an examination (3.21) to yield results that are correlated with a particular clinical condition,
physiological or pathological state in accordance with the target population and intended use(r)
Note 1 to entry: Although sometimes referred to as diagnostic performance or clinical validity; clinical performance
is the harmonized term endorsed by the Global Harmonization Task Force (GHTF) and its successor, the International
Medical Devices Regulators Forum (IMDRF).
Note 2 to entry: Evaluation of clinical performance often relies on the outcome of other types of clinical examinations
to define “true positive or true negative” results.
3.12
clinical sensitivity
diagnostic sensitivity
ability of an in vitro diagnostic examination procedure to have positive results associated with a particular
disease or condition
Note 1 to entry: Also defined as percent positivity in samples where the target marker is known to be present.
Note 2 to entry: Diagnostic sensitivity is expressed as a percentage (number fraction multiplied by 100), calculated as
100 × the number of true positive values (TP) divided by the sum of the number of true positive values (TP) plus the
number of false negative values (FP), or 100 × TP/(TP + FN). This calculation is based on a study design where only
one sample is taken from each subject.
Note 3 to entry: The target condition is defined by criteria independent of the examination procedure under
consideration.
Note 4 to entry: Clinical sensitivity is often confused with positive percentage agreement (PPA), because the same
calculations are used for both the clinical sensitivity and the PPA. However, the term PPA instead of clinical sensitivity
is only used, if a reference method is not available or is not used. The PPA represents merely an estimation of the
clinical sensitivity.
[SOURCE: ISO 18113-1:2022, 3.2.17, modified — The term "clinical sensitivity" was added; second sentence
in Note 1 was deleted; Note 4 was added.]
3.13
clinical specificity
diagnostic specificity
ability of an in vitro diagnostic examination procedure to have negative results associated with an absence
of particular disease or condition
Note 1 to entry: Also defined as percent negativity in samples where the target marker is known to be absent. For
information regarding description of the diagnostic performance characteristics of an IVD medical device, see
Reference [4].
Note 2 to entry: Clinical specificity is expressed as a percentage (number fraction multiplied by 100), calculated as
100 × the number of true negative values (TN) divided by the sum of the number of true negative plus the number of
false positive values (FP), or 100 × TN/(TN + FP). This calculation is based on a study design where only one sample is
taken from each subject.
ISO/DIS 25379-2:2026(en)
Note 3 to entry: The target condition is defined by criteria independent of the examination procedure under
consideration.
Note 4 to entry: Clinical specificity is often confused with negative percentage agreement (NPA), because the same
calculations are used for both the clinical specificity and the NPA. However, the term NPA instead of clinical specificity
is only used, if a reference method is not available or is not used. The NPA represents merely an estimation of the
clinical specificity.
[SOURCE: ISO 18113-1:2022, 3.2.18, modified — The term "clinical specificity" was added; Note 4 was
added.]
3.14
clinical utility
ability of a screening or diagnostic examination to prevent or ameliorate adverse health outcomes such as
mortality, morbidity, or disability through the adoption of efficacious treatments conditioned on examination
results
[5] [6]
Note 1 to entry: Clinical utility can be part of scientific validity and clinical performance (3.11) , .
[6]
[SOURCE: ]
3.15
clinical validity
predictive value of an examination (3.21) for a given clinical outcome
Note 1 to entry: Clinical validity is primarily determined by the clinical sensitivity (3.12) and clinical specificity (3.13)
with which an examination identifies individuals with a defined clinical condition within a given population. The
clinical validity of a genetic examination is the likelihood that, e.g. cancer will develop in someone with a positive
examination result.
3.16
closed system
non-modifiable system (by the user) provided by the vendor including all necessary components for the
examination
Note 1 to entry: Necessary components are hardware, software, procedures and reagents.
3.17
Design of Experiments
DoE
structured, statistical approach for planning sequencing runs and experimental conditions in order
to systematically evaluate the effects of key variables (e.g. library preparation methods, input nucleic acid
quantity, sequencing depth, and indexing strategies) on sequencing quality, coverage, and downstream data
interpretation
3.18
deoxyribonuclease
DNase
enzyme that catalyzes the degradation of DNA (3.19) into smaller components
[SOURCE: ISO 20186-3:2019, 3.9]
3.19
deoxyribonucleic acid
DNA
polymer of deoxyribonucleotides occurring in a double-stranded (dsDNA) or single-stranded (ssDNA) form
3.20
diagnosis
identification of a disease from its signs and symptoms, where the diagnostic process can involve
examinations (3.21) and tests for classification of an individual's condition into separate and distinct
categories or subclasses that allow medical decisions about treatment and prognosis to be made

ISO/DIS 25379-2:2026(en)
3.21
examination
analytical test
set of operations having the objective of determining the numerical value or characteristics of a property
Note 1 to entry: An examination can be the total of a number of activities, observations or measurements required to
determine a value or characteristic.
Note 2 to entry: Laboratory examinations that determine a numerical value of a property are called "quantitative
examinations"; those that determine the characteristics of a property are called "qualitative examinations".
Note 3 to entry: Laboratory examinations are also called "assays" or "tests".
Note 4 to entry: A “measurement procedure” or “measurement system” becomes an “examination” (also in complex
terms like “examination procedure”), where nominal properties (e.g. DNA bases like G, A, T, C, or a set of terms for the
types of leukocytes found in human blood) or ordinal quantities (e.g. a 5-value scale (0, 1, 2, 3, 4) for dip-stick reading
(assessed using 1 = not elevated, 2 = doubtfully elevated, 3 = slightly elevated, 4 = elevated, 5 = strongly elevated)) are
the results of a “detection” instead of a “measurement” [derived from ISO/DIS 15193] .
[SOURCE: ISO 15189:2022, 3.8, modified — The term "analytical test" was added; note 1 was added.]
3.22
examination manufacturer
analytical test manufacturer
entity that manufactures and/or produces measurement or detection systems, instruments, and reagents
for a specific examination (3.21)
3.23
examination performance
analytical test performance
analytical performance
ability of an examination procedure to measure or detect a particular analyte (3.3)
Note 1 to entry: Analytical performance is determined from analytical performance studies used to assess the ability
of an in vitro diagnostic examination procedure to measure or detect a particular analyte (3.3).
Note 2 to entry: Analytical performance includes such characteristics as analytical sensitivity, detection limit,
analytical specificity (interference and cross-reactivity), trueness, precision and linearity.
[SOURCE: ISO 20186-3:2019, 3.11]
3.24
extracellular vesicle
EV
particle naturally released from the cell that is delimited by a lipid bilayer and cannot replicate, i.e. does not
contain a functional nucleus
EXAMPLE Exosomes, endosomes, oncosomes, apoptotic bodies.
[7]
[SOURCE: ]
3.25
fine needle aspirate
FNA
specimen (3.72) withdrawn by a non-operative procedure that uses a thin, hollow-bore needle
[60]
[SOURCE: CEN/TS 17688-1:2021, 3.18 ]
3.26
formalin
saturated aqueous formaldehyde solution which at 100 % contains 37 % formaldehyde by mass
(corresponding to 40 % by volume)
[SOURCE: ISO 20166-1:2018, 3.11]

ISO/DIS 25379-2:2026(en)
3.27
fraser
[13]
detection enhancement method of aberrant splicing events in RNA-seq data
3.28
guard band
interval between a tolerance limit and a corresponding acceptance limit
Note 1 to entry: The guard band includes the limits.
[SOURCE: ISO/IEC Guide 98-4:2012, 3.3.11]
3.29
in vitro diagnostic NGS workflow
all activities required to generate the NGS examination result including the pre-examination processes (3.50),
examination (3.21) and post-examination processes (3.49)
3.30
intended use
intended purpose
objective regarding the application of a product, process or service as reflected in the specifications,
instructions and information provided by the examination manufacturer (3.22)
Note 1 to entry: Intended use statements for IVD labelling can include two components: a description of the
functionality of the IVD medical device (e.g. an immunochemical measurement procedure for the detection of analyte
(3.3) “x” in serum or plasma), and a statement of the intended medical use of the examination results.
Note 2 to entry: The intended use can include the indications for use.
Note 3 to entry: The intended purpose indicates the object to be detected/measured, the examination’s function
(screening, monitoring, diagnosis, prognosis, companion diagnostic), if the examination is automated, specific
information to be provided as a component of the device (to determine physiological/pathological state, clinical
condition or predisposition, prediction to treatment response/reaction or monitoring of a therapy or non-proprietary
name of the medicinal product for companion test; safety to recipients), if the examination results are qualitative or
quantitative, the type of specimen required, and the intended population.
Note 4 to entry: The intended purpose directly drives the level of the performance evaluation, the examination
methodology, the hardware and software, the examination limitations, positive controls, risk to health (e.g. diagnostic
use or screening; consequences of false negatives (FN) or false positives (FP)), the number of samples, and the types
of samples.
[SOURCE: ISO 18113-1:2022(en), 3.1.37, modified ― Eliminated circularity and repetition in the defenition;
two Notes to entry added; “the IVD manufacturer” is replaced with “examination manufacturer”; “supplied”
is replaced with “provided”.]
3.31
intermediate precision
intermediate measurement precision
measurement precision under a set of intermediate precision conditions of measurement (3.32)
Note 1 to entry: Relevant statistical terms are given in ISO 5725-3:1994.
[SOURCE: ISO/IEC Guide 99:2007, 2.23]
3.32
intermediate precision condition of measurement
intermediate precision condition
condition of measurement (3.40), out of a set of conditions that includes the same measurement procedure
(3.41), same location, and replicate measurements on the same or similar objects over an extended period of
time, but can include other conditions involving changes
Note 1 to entry: The changes can include new calibrations, calibrators, operators, and measuring systems.

ISO/DIS 25379-2:2026(en)
Note 2 to entry: A specification for the conditions should contain the conditions changed and unchanged, to the extent
practical.
Note 3 to entry: In chemistry, the term “inter-serial precision condition of measurement” is sometimes used to
designate this concept.
[SOURCE: ISO/IEC Guide 99:2007, 2.22, modified – "may" replaced by "can"]
3.33
isoform
member of a set of highly similar RNA transcripts or proteins that originate from a single gene or gene family
3.34
laboratory developed examination
in-house examination
laboratory developed test
examination (3.21) manufactured or modified and used by health institutions or medical laboratories
intended to be used only in their facility, to fulfil specific needs of target patient groups which cannot be met
by an equivalent IVD examination available on the market at the appropriate level of performance
3.35
limit of detection
detection limit
LOD
measured quantity value, obtained by a given measurement procedure (3.41), for which the probability of
falsely claiming the absence of a component in a material is β, given a probability α of falsely claiming its
presence
Note 1 to entry: IUPAC recommends default values for α and β equal to 0,05.
Note 2 to entry: The term “sensitivity” is discouraged for this concept.
Note 3 to entry: Where the target sequence is a mixture of detectable and non-detectable sequences, the parameter
LODP (3.36) (ISO 16578), which indicates the lower limit of detection for the platform, should be considered for use
instead of LOD.
[SOURCE: ISO/IEC Guide 99:2007, 4.18, modified — Note 2 was deleted; Note 3 was added.]
3.36
limit of detection for platforms
platform limit of detection
LODP
lowest relative quantity of the external measurement standard or reference material (3.53) for which a
positive identification can be achieved with reasonable or previously determined confidence or both in a
defined matrix using a specific analytical method
Note 1 to entry: In qualitative testing, an estimate of the LOD is measured at the chosen probability of detection (POD).
[SOURCE: ISO 16578:2022(en), 3.1]
3.37
long-read sequencing
subset of massively parallel sequencing (MPS) (3.38) methods capable of measuring nucleic acid sequences of
≥2 kb, that can directly detect DNA bases, RNA bases and nucleic base modifications
Note 1 to entry: Long-read sequencing can be achieved by two approaches at the moment (enzymatic processing or
direct reading).
ISO/DIS 25379-2:2026(en)
3.38
massively parallel sequencing
MPS
nucleic acid sequencing techniques that detect millions or billions of sequences from individual input nucleic
acid molecules in parallel
Note 1 to entry: For DNA sequencing, alleles are analysed separately. Combining allele sequences is required to
determine a genotype of a donor/patient at any tested position of the genome. For RNA sequencing, locus-specific
sequences from coding and non-coding RNAs are analysed by counting and/or by determining exon coverage or exon
usage to determine splicing.
Note 2 to entry: Massively parallel sequencing technology can provide millions or billions of reads per run.
3.39
measurand
quantity intended to be measured
Note 1 to entry: In chemistry, “analyte”, or the name of a substance or compound, are terms sometimes used for
‘measurand’. This usage is erroneous because these terms do not refer to quantities.
EXAMPLE Amount of substance of glucose in plasma is a measurand, while glucose is the analyte (3.3).
[SOURCE: ISO/IEC Guide 99:2007, 2.3, modified —Note 1 to 3 and Example 1 to 2 were deleted; a new
example was added.]
3.40
measurement
process of experimentally obtaining one or more quantity values that can reasonably be attributed to
a quantity
Note 1 to entry: Measurement does not apply to nominal properties.
Note 2 to entry: Measurement implies comparison of quantities or counting of entities.
Note 3 to entry: Measurement presupposes a description of the quantity commensurate with the intended use of
a measurement result, a measurement procedure, and a calibrated measuring system operating according to the
specified measurement pr
...