The FISH technique - Fluorescent in situ hybridization, was developed in the mid-1980s and is used to detect the presence or absence of specific DNA sequences on chromosomes, as well as an alpha satellite DNA localized on the centromere of chromosome 6, CEP6 (6p11.1-q11. one).

This gave a significant shift in the diagnosis of oncological diseases of melanocytic genesis occurred in connection with the detection of tumor antigens. Against the background of a malignant, mutation is determined in three antigens: CDK2NA (9p21), CDK4 (12q14) and CMM1 (1p). In this regard, the possibility of an objective differential diagnosis based on the determination of the genetic characteristics of melanocytic skin tumors is of great importance in the early diagnosis of melanoma and its precursors. In the nucleus with a normal set of studied genes and chromosome 6, there are two RREB1 genes stained with red, two MYB genes colored yellow, two CCND1 genes highlighted in green, and two centromeres of chromosome 6, highlighted in blue. For diagnostic purposes, fluorescent samples are used.

Evaluation of the reaction results: the number of red, yellow, green and blue signals in 30 nuclei of each sample is counted, four parameters of various variants of genetic disorders are identified, in which the sample genetically corresponds to melanoma. For example, a sample matches melanoma if the average CCND1 gene per nucleus is ≥2.5. The same principle is used to assess the copy number of other genes. A drug is considered FISH positive if at least one of four conditions is met. Samples in which all four parameters are below cut-off values ​​are considered FISH negative.

Determination of specific DNA sequences on chromosomes is carried out on sections of biopsies or surgical material. In practice, the FISH reaction looks like this: the test material containing DNA in the nuclei of melanocytes is processed to partially destroy its molecule in order to break the double-stranded structure and thereby facilitate access to the desired gene region. Samples are classified according to the place of attachment to the DNA molecule. The material for the FISH reaction in clinical practice is paraffin tissue sections, smears, and prints.

The FISH reaction allows you to find changes that have occurred in the DNA molecule as a result of an increase in the number of copies of a gene, loss of a gene, changes in the number of chromosomes and qualitative changes - the movement of gene loci both in the same chromosome and between two chromosomes.

To process the data obtained using the FISH reaction and to study the relationship between the copy number of genes of the three study groups, the Spearman correlation coefficient is used.

Melanoma is characterized by an increase in copy number compared to a nevus and dysplastic nevus.

A simple nevus, compared to a dysplastic nevus, has fewer copy number abnormalities (i.e., more normal copy numbers).

Decision trees are used to construct decision rules to predict whether a sample belongs to a particular class (differential diagnosis of simple and dysplastic nevi). This approach has proven itself in practice, and the results of the application of this method (in contrast to many other methods, for example, neural networks) can be clearly interpreted to construct decision rules for differentiating simple, dysplastic nevi and melanoma. The initial data in all cases were the number of copies of four genes.

The problem of constructing a decision rule for differential diagnostics is divided into several stages. At the first stage, melanoma and nevus are differentiated, without taking into account the type of nevus. At the next stage, a decision rule is built to separate simple and dysplastic nevi. Finally, at the last stage, it is possible to build a "decision tree" to determine the degree of dysplasia of the dysplastic nevus.

Such a division of the problem of classifying nevi into subtasks allows achieving high prediction accuracy at each stage. The input data for constructing a "decision tree" are data on the copy number of four genes for patients with a diagnosis of "melanoma" and patients with a diagnosis of "non-melanoma" (patients with different types of nevus - simple and dysplastic). For each patient, there is data on the gene copy number for 30 cells.

Thus, dividing the problem of predicting the diagnosis into several stages allows one to build high-precision decision rules not only for differentiating between melanoma and nevi, but also for determining the type of nevi and predicting the degree of dysplasia for a dysplastic nevus. The constructed "decision trees" are a visual way to predict the diagnosis based on the data on gene copies and can be easily used in clinical practice in differentiating benign, pre-malignant and malignant melanocytic skin neoplasms. The proposed additional method of differential diagnosis is especially important for excision of giant congenital pigmented nevi and dysplastic nevi in ​​pediatric patients, since a high percentage of diagnostic errors is noted when such patients apply to medical institutions. The results of using the described method are highly effective, it is advisable to use it in the diagnosis of pigmented skin tumors, especially in patients with FAMM syndrome.

Invasive methods of prenatal diagnostics allow not only to look into the future and reliably predict whether an unborn baby is expecting diseases associated with intrauterine malformations, but also to find out the nature and causes of congenital pathologies.

However, any information has value only when it is timely. When it comes to the state of development of the fetus, the speed of obtaining test results becomes vital.

Therefore, the FISH method, which makes it possible to assess the presence of the most common developmental abnormalities in the embryo as soon as possible, is in great demand in genetic diagnostics.

FISH stands for fluorescence in situ hybridization - fluorescent hybridization in a “home” environment.

This technique, proposed in the late 70s of the last century by J. Goll and M.-L. Pardew, is based on the possibility of restoring the sequence of the arrangement of nucleic acid fragments (DNA or RNA) after their denaturation.

The authors have developed a method that allows, using in situ hybridization of artificially created labeled DNA probes (probes) and cytogenetic material taken for analysis, to identify quantitative and qualitative deviations of the chromosomes of interest.

At the end of the last century, after the successful use of fluorescent dyes for staining DNA probes, the FISH method got its name and since then has been intensively improved and varied.

Modern methods of FISH analysis strive to ensure that it is possible to obtain the most complete information for the analysis of the collected genetic material in one hybridization procedure.

The fact is that once after hybridization, only a limited number of chromosomes of the same cytogenetic material can be estimated. The ability to re-hybridize DNA strands decreases from time to time.

Therefore, at the moment in genetic diagnostics, the in situ hybridization method is most often used to quickly answer questions about the available, most common aneuploidies for 21, 13, 18 chromosomes, as well as for sex chromosomes X, Y.

Any tissue or cell sample is suitable for FISH analysis.

In prenatal diagnosis, these can be blood, ejaculate, or blood samples.

The speed of obtaining the results is ensured by the fact that the cells obtained from the material taken for analysis do not need to be cultured in nutrient media, achieving their division to the required amount, as in the classical method of karyotyping.

The selected material undergoes special preparation to obtain a concentrated pure cell suspension. Next, the process of denaturation of the DNA sample and native DNA of the test sample to a single-stranded state and the process of hybridization are carried out, during which the stained DNA probes are incubated with the DNA of the sample.

Thus, the desired (stained) chromosomes in the cell are visualized, their number, the structure of genetic structures, etc. are estimated. The eyepiece of a special fluorescence microscope allows you to examine the luminous DNA strands.

Currently, the FISH method is widely used for diagnostic purposes to detect genetic diseases, chromosomal aberrations in reproductive medicine, oncology, hematology, biological dosimetry, etc.

How is fetal FISH diagnostics used?

In the field of reproductive medicine, the FISH method, as one of the methods of molecular cytogenetic diagnostics, is used at all stages.

• a couple.

To determine the karyotype of future parents, it is carried out once, since the human genome is unchanged throughout life.

Karyotyping a couple before conceiving a child will help to identify whether parents are carriers of genetic pathologies that are inherited, including hidden ones. As well as the general state of the genome of future mothers and fathers, which can affect the success of conceiving a baby and carrying a pregnancy.

Diagnosis by the FISH method in this case often acts as an additional examination to classical karyotyping, when chromosomal abnormalities are detected in the test material (venous blood of the parents), if there is a suspicion of mosaicism.

An additional examination by the FISH method will reliably confirm or deny the presence of a suspected abnormality in the cells of the future parent.

• Ejaculate research.

It is indicated for difficulties with reproduction in pairs according to the "male factor". Sperm analysis by the FISH method will assess the level of sperm that are abnormal in the chromosomal set, and also determine whether a man is a carrier of gender-linked genetic diseases.

If the couple later resorts to conception with the help of IVF, FISH analysis of the ejaculate will select the highest quality sperm for fertilization of the egg.

• With IVF.

For preimplantation genetic diagnosis (PGD). Based on the results of studies of the karyotype of parents, possible chromosomal, genetic aberrations that can be transferred to the embryo are determined.

Thanks to the possibilities of FISH-diagnostics, the study of the genetic health of the formed embryos can be carried out in a matter of hours before transfer to the uterine cavity, in order to ensure the onset of pregnancy with a known healthy fetus.

In addition, the possibilities of PGD allow you to determine the sex of the embryos, and, therefore, "order" the sex of the unborn child, if necessary.

• During gestation period.

In prenatal diagnosis: FISH analysis of fetal cells obtained by chorionic villus sampling, amniocentesis or cordocentesis is usually offered by medical centers in addition to classical genetic testing of fetal cells (karyotyping).

This method is indispensable when it is necessary to quickly receive an answer about the presence of the most common chromosomal defects in the fetus: trisomy for 21, 18, 13 chromosomes, aberrations in chromosomes X and Y, sometimes also aneuploidies for 14 (or 17), 15, 16 chromosomes.

Benefits of FISH Analysis

FISH genetic analysis, although it remains today an auxiliary method for diagnosing chromosomal pathologies, however, its expediency determines undeniable advantages:

• the speed of obtaining results concerning the tested chromosomes - within a few hours - no more than 72.

This can be important if the fate of pregnancy depends on the diagnosis of geneticists;

• high sensitivity and reliability of the FISH method — successful analysis is possible on an insignificant amount of biomaterial - one cell is enough, the error of the results is not more than 0.5%.

This can be important when the number of cells in the initial sample is limited, for example, when their division is poor.

• the possibility of FISH diagnostics at any stage of pregnancy (from the 7th week) and according to any biological sample: chorionic fragments, amniotic fluid, fetal blood, etc.

Where can I make a diagnosis by the FISH method?

In Moscow, the FISH method for prenatal diagnosis of fetal chromosomal abnormalities is used in the following medical centers:

As a rule, clinics offer a FISH diagnostic service within the framework of complete karyotyping of the fetus through invasive intervention for an additional fee. And, as a rule, future parents agree to pay extra, because thanks to the FISH method, in a couple of days you can find out the most important thing about your baby

Head of
"Oncogenetics"

Zhusina
Yulia Gennadevna

Graduated from the pediatric faculty of the Voronezh State Medical University named after V.I. N.N. Burdenko in 2014.

2015 - internship in therapy at the Department of Faculty Therapy of V.G. N.N. Burdenko.

2015 - Certification course in the specialty "Hematology" on the basis of the Hematological Scientific Center in Moscow.

2015-2016 - physician therapist, VGKBSMP №1.

2016 - the topic of the dissertation for the degree of candidate of medical sciences "study of the clinical course of the disease and prognosis in patients with chronic obstructive pulmonary disease with anemic syndrome" was approved. Co-author of over 10 publications. Participant of scientific and practical conferences on genetics and oncology.

2017 - refresher course on the topic: "interpretation of the results of genetic studies in patients with hereditary diseases."

Since 2017, residency in the specialty "Genetics" on the basis of the RMANPO.

Head of
"Genetics"

Kanivets
Ilya Viacheslavovich

Kanivets Ilya Vyacheslavovich, geneticist, candidate of medical sciences, head of the genetics department of the Genomed medical and genetic center. Assistant of the Department of Medical Genetics of the Russian Medical Academy of Continuing Professional Education.

He graduated from the medical faculty of the Moscow State University of Medicine and Dentistry in 2009, and in 2011 - his residency in Genetics at the Department of Medical Genetics of the same university. In 2017 he defended his thesis for the degree of candidate of medical sciences on the topic: Molecular diagnostics of variations in the number of copies of DNA regions (CNVs) in children with congenital malformations, phenotype abnormalities and / or mental retardation when using SNPs of high-density oligonucleotide microarrays "

From 2011-2017 he worked as a geneticist at the Children's Clinical Hospital named after N.F. Filatov, Scientific Advisory Department of the Federal State Budgetary Scientific Institution "Medical Genetic Research Center". From 2014 to the present, he has been the head of the genetics department at MGC Genomed.

The main areas of activity: diagnostics and management of patients with hereditary diseases and congenital malformations, epilepsy, medical and genetic counseling of families in which a child was born with hereditary pathology or developmental defects, prenatal diagnostics. During the consultation, clinical data and genealogy are analyzed to determine the clinical hypothesis and the required amount of genetic testing. Based on the results of the survey, the data are interpreted and the information received is explained to the consultants.

He is one of the founders of the School of Genetics project. Speaks regularly at conferences. Gives lectures for doctors, geneticists, neurologists and obstetricians-gynecologists, as well as for parents of patients with hereditary diseases. She is the author and co-author of more than 20 articles and reviews in Russian and foreign journals.

The area of ​​professional interests is the introduction of modern genome-wide studies into clinical practice, the interpretation of their results.

Reception time: Wed, Fri 16-19

Head of
"Neurology"

Sharkov
Artem Alekseevich

Sharkov Artyom Alekseevich- neurologist, epileptologist

In 2012, he studied under the international program "Oriental medicine" at the Daegu Haanu University in South Korea.

Since 2012 - participation in the organization of a database and an algorithm for the interpretation of genetic tests xGenCloud (https://www.xgencloud.com/, Project Manager - Igor Ugarov)

In 2013 graduated from the Pediatric Faculty of the Russian National Research Medical University named after N.I. Pirogov.

From 2013 to 2015 he studied in clinical residency in neurology at the Scientific Center of Neurology.

Since 2015, he has been working as a neurologist, research assistant at the Academician Yu.E. Veltischev N.I. Pirogov. He also works as a neurologist and doctor of the video-EEG monitoring laboratory in the clinics “Center for Epileptology and Neurology named after V.I. A.A. Kazaryan "and" Epilepsy Center ".

In 2015, he studied in Italy at the “2nd International Residential Course on Drug Resistant Epilepsies, ILAE, 2015” school.

In 2015, advanced training - "Clinical and molecular genetics for practicing doctors", RCCH, RUSNANO.

In 2016, advanced training - "Fundamentals of Molecular Genetics" under the guidance of bioinformatics, Ph.D. Konovalova F.A.

Since 2016 - the head of the neurological department of the Genomed laboratory.

In 2016, he studied in Italy at the school "San Servolo international advanced course: Brain Exploration and Epilepsy Surger, ILAE, 2016".

In 2016, advanced training - "Innovative genetic technologies for doctors", "Institute of laboratory medicine".

In 2017 - the school "NGS in Medical Genetics 2017", Moscow State Scientific Center

Currently, he conducts scientific research in the field of epilepsy genetics under the guidance of Professor, MD. Belousova E.D. and professors, d.m.s. Dadali E.L.

The topic of the dissertation for the degree of candidate of medical sciences "Clinical and genetic characteristics of monogenic variants of early epileptic encephalopathies" was approved.

The main areas of activity are the diagnosis and treatment of epilepsy in children and adults. Narrow specialization - surgical treatment of epilepsy, epilepsy genetics. Neurogenetics.

Scientific publications

Sharkov A., Sharkova I., Golovteev A., Ugarov I. "Optimization of differential diagnosis and interpretation of the results of genetic testing by the XGenCloud expert system in some forms of epilepsy." Medical genetics, no. 4, 2015, p. 41.
*
Sharkov A.A., Vorobiev A.N., Troitsky A.A., Savkina I.S., Dorofeeva M.Yu., Melikyan A.G., Golovteev A.L. "Surgery of epilepsy for multifocal brain lesions in children with tuberous sclerosis." Abstracts of the XIV Russian Congress "INNOVATIVE TECHNOLOGIES IN PEDIATRICS AND PEDIATRIC SURGERY". Russian Bulletin of Perinatology and Pediatrics, 4, 2015. - p. 226-227.
*
Dadali E.L., Belousova E.D., Sharkov A.A. "Molecular genetic approaches to the diagnosis of monogenic idiopathic and symptomatic epilepsies". Thesis of the XIV Russian Congress "INNOVATIVE TECHNOLOGIES IN PEDIATRICS AND PEDIATRIC SURGERY". Russian Bulletin of Perinatology and Pediatrics, 4, 2015. - p. 221.
*
Sharkov A.A., Dadali E.L., Sharkova I.V. "A rare variant of early type 2 epileptic encephalopathy caused by mutations in the CDKL5 gene in a male patient." Conference "Epileptology in the System of Neurosciences". Collection of conference materials: / Edited by prof. Neznanova N.G., prof. Mikhailova V.A. SPb .: 2015. - p. 210-212.
*
Dadali E.L., Sharkov A.A., Kanivets I.V., Gundorova P., Fominykh V.V., Sharkova I, V ,. Troitsky A.A., Golovteev A.L., Polyakov A.V. A new allelic variant of type 3 myoclonus epilepsy caused by mutations in the KCTD7 gene // Medical genetics. -2015.- v. 14.- No. 9.- p. 44-47
*
Dadali E.L., Sharkova I.V., Sharkov A.A., Akimova I.A. "Clinical and genetic features and modern methods of diagnosing hereditary epilepsies." Collection of materials "Molecular biological technologies in medical practice" / Ed. Corresponding Member RAYEN A.B. Maslennikov. - Issue. 24.- Novosibirsk: Akademizdat, 2016.- 262: p. 52-63
*
Belousova E.D., Dorofeeva M.Yu., Sharkov A.A. Epilepsy in tuberous sclerosis. In "Diseases of the brain, medical and social aspects" edited by Gusev EI, Gekht AB, Moscow; 2016; pp. 391-399
*
Dadali E.L., Sharkov A.A., Sharkova I.V., Kanivets I.V., Konovalov F.A., Akimova I.A. Hereditary diseases and syndromes accompanied by febrile seizures: clinical and genetic characteristics and diagnostic methods. // Russian Journal of Pediatric Neurology.- T. 11.- №2, p. 33- 41.doi: 10.17650 / 2073-8803- 2016-11- 2-33- 41
*
Sharkov A.A., Konovalov F.A., Sharkova I.V., Belousova E.D., Dadali E.L. Molecular genetic approaches to the diagnosis of epileptic encephalopathy. Collection of abstracts "VI BALTIC CONGRESS ON CHILD NEUROLOGY" / Edited by Professor Guzeva V.I. St. Petersburg, 2016, p. 391
*
Hemispherotomy for pharmacoresistant epilepsy in children with bilateral brain damage Zubkova N.S., Altunina G.E., Zemlyansky M.Yu., Troitsky A.A., Sharkov A.A., Golovteev A.L. Collection of abstracts "VI BALTIC CONGRESS ON CHILD NEUROLOGY" / Edited by Professor Guzeva V.I. St. Petersburg, 2016, p. 157.
*
*
Article: Genetics and differential treatment of early epileptic encephalopathy. A.A. Sharkov *, I. V. Sharkova, E. D. Belousova, E.L. Dadali. Journal of Neurology and Psychiatry, 9, 2016; Issue 2doi: 10.17116 / jnevro 20161169267-73
*
Golovteev A.L., Sharkov A.A., Troitsky A.A., Altunina G.E., Zemlyansky M.Yu., Kopachev D.N., Dorofeeva M.Yu. "Surgical treatment of epilepsy in tuberous sclerosis" edited by M. Dorofeeva, Moscow; 2017; page 274
*
New international classifications of epilepsy and epileptic seizures of the International League Against Epilepsy. Journal of Neurology and Psychiatry. C.C. Korsakov. 2017.Vol. 117.No. 7.P. 99-106

Head of
"Prenatal diagnosis"

Kievskaya
Yulia Kirillovna

In 2011 she graduated from the Moscow State University of Medicine and Dentistry. A.I. Evdokimova with a degree in General Medicine She studied in residency at the Department of Medical Genetics of the same university with a degree in Genetics

In 2015, she graduated from an internship in the specialty of Obstetrics and Gynecology at the Medical Institute for Advanced Training of Doctors of the FSBEI HPE "MGUPP"

Since 2013, he has been conducting a consultative reception at the State Budgetary Healthcare Institution "Center for Family Planning and Reproduction" DZM

Since 2017, he has been the head of the Prenatal Diagnostics department of the Genomed laboratory

Speaks regularly at conferences and seminars. Gives lectures for doctors of various specialties in the field of reproduction and prenatal diagnostics

Conducts medical and genetic counseling for pregnant women on prenatal diagnostics in order to prevent the birth of children with congenital malformations, as well as families with presumably hereditary or congenital pathologies. Interprets the results of DNA diagnostics.

SPECIALISTS

Latypov
Arthur Shamilevich

Latypov Artur Shamilevich - doctor geneticist of the highest qualification category.

After graduating from the medical faculty of the Kazan State Medical Institute in 1976, he worked for many first as a doctor in the office of medical genetics, then as the head of the medical genetics center of the Republican Hospital of Tatarstan, chief specialist of the Ministry of Health of the Republic of Tatarstan, teacher of the departments of Kazan Medical University.

Author of over 20 scientific papers on problems of reproductive and biochemical genetics, participant in many national and international congresses and conferences on problems of medical genetics. Introduced methods of mass screening of pregnant women and newborns for hereditary diseases into the practical work of the center, carried out thousands of invasive procedures for suspected hereditary diseases of the fetus at different stages of pregnancy.

Since 2012 she has been working at the Department of Medical Genetics with a course of prenatal diagnostics of the Russian Academy of Postgraduate Education.

Research interests - metabolic diseases in children, prenatal diagnostics.

Reception time: Wed 12-15, Sat 10-14

Reception of doctors is carried out by appointment.

Doctor-geneticist

Gabelko
Denis Igorevich

In 2009 he graduated from the medical faculty of KSMU named after S. V. Kurashova (specialty "General Medicine").

Internship at the St. Petersburg Medical Academy of Postgraduate Education of the Federal Agency for Healthcare and Social Development (specialty "Genetics").

Internship in therapy. Primary retraining in the specialty "Ultrasound diagnostics". Since 2016, he has been a member of the Department of Fundamental Foundations of Clinical Medicine of the Institute of Fundamental Medicine and Biology.

Sphere of professional interests: prenatal diagnostics, the use of modern screening and diagnostic methods to identify the genetic pathology of the fetus. Determination of the risk of recurrence of hereditary diseases in the family.

Participant of scientific and practical conferences on genetics and obstetrics and gynecology.

Work experience 5 years.

Consultation by appointment

Reception of doctors is carried out by appointment.

Doctor-geneticist

Grishina
Kristina Alexandrovna

Graduated in 2015 from the Moscow State Medical and Dental University with a degree in General Medicine. In the same year she entered the residency in the specialty 30.08.30 "Genetics" at the Federal State Budgetary Scientific Institution "Medical Genetic Research Center".
She was hired to work at the Laboratory of Molecular Genetics of Difficult Inherited Diseases (headed by A.V. Karpukhin, Doctor of Biological Sciences) in March 2015 as a research laboratory assistant. Since September 2015, she has been transferred to the position of a research assistant. He is the author and co-author of more than 10 articles and abstracts on clinical genetics, oncogenetics and molecular oncology in Russian and foreign journals. Regular participant of conferences on medical genetics.

Field of scientific and practical interests: medical and genetic counseling of patients with hereditary syndromic and multifactorial pathology.

A consultation with a geneticist allows you to answer the questions:

whether the child's symptoms are signs of a hereditary disorder what research is needed to identify the cause determining an accurate forecast recommendations for the conduct and assessment of the results of prenatal diagnostics everything you need to know when planning a family IVF planning consultation on-site and online consultations

She took part in the scientific and practical school "Innovative genetic technologies for doctors: application in clinical practice", the conference of the European Society of Human Genetics (ESHG) and other conferences dedicated to human genetics.

Conducts medical and genetic counseling for families with presumably hereditary or congenital pathologies, including monogenic diseases and chromosomal abnormalities, determines indications for laboratory genetic studies, interprets the results of DNA diagnostics. Consults pregnant women on prenatal diagnostics in order to prevent the birth of children with congenital malformations.

Geneticist, obstetrician-gynecologist, candidate of medical sciences

Kudryavtseva
Elena Vladimirovna

Geneticist, obstetrician-gynecologist, candidate of medical sciences.

Specialist in the field of reproductive counseling and hereditary pathology.

Graduated from the Ural State Medical Academy in 2005.

Residency in Obstetrics and Gynecology

Internship in Genetics

Professional retraining in the specialty "Ultrasound diagnostics"

Activities:

• Infertility and miscarriage
Vasilisa Yurievna



She is a graduate of the Nizhny Novgorod State Medical Academy, the Faculty of General Medicine (specialty "General Medicine"). She graduated from the clinical residency at the Moscow State Scientific Center for Genetics. In 2014, she completed an internship at the clinic for mothers and children (IRCCS materno infantile Burlo Garofolo, Trieste, Italy).

Since 2016 he has been working as a consultant physician at Genomed LLC.

Regularly participates in scientific and practical conferences on genetics.

Main areas of activity: Consulting on clinical and laboratory diagnostics of genetic diseases and interpretation of results. Management of patients and their families with presumably hereditary pathology. Consulting in planning pregnancy, as well as during pregnancy on prenatal diagnostics in order to prevent the birth of children with congenital pathology.

The FISH test is one of the most modern methods for analyzing the chromosome set. The abbreviation "FISH" itself was formed from the English name of the technique - fluorescent in situ hybridization. This test allows you to study the genetic material of a cell with high accuracy (including specific genes and their segments).

This method is used today to diagnose some types of cancerous tumors, since the malignant transformation of a cell is caused by changes in its genome. Accordingly, having found characteristic abnormalities in genes, one can reliably classify this cell as cancerous. In addition, the FISH test is also used to confirm an already established diagnosis, as well as to obtain additional data on the possibility of using specific chemotherapy drugs in order to conduct chemotherapy for breast cancer and clarify the prognosis of the disease.

A good example of the use of the FISH test is in breast cancer patients. With this technique, biopsy tissue is examined for copies of a gene called HER-2. If this gene is present, it means that a large number of HER2 receptors are located on the cell surface. They are sensitive to signals that stimulate the development and reproduction of tumor elements. In this case, an opportunity opens up for the effective use of trastuzumab - this drug blocks the activity of HER2 receptors, which means it inhibits tumor growth.

How is the FISH test done?

During the examination, a special dye containing fluorescent labels is injected into the biomaterial obtained from the patient. Their chemical structure is such that they are able to bind exclusively to well-defined regions of the chromosomal set of the cell. The stained tissue sample is then placed under a fluorescence microscope. If a researcher discovers sections of chromosomes with luminous marks attached to them, then this is an indicator of deviations that indicate the presence of changes in the genome related to the oncological type.

These deviations in the structure of chromosomes are of several types:
translocation - the movement of a part of the chromosomal material to a new position within the same or a different chromosome;
inversion - rotation of a part of the chromosome by 1800 without separating from its main body;
deletion - loss of any chromosomal region;
duplication - copying a part of a chromosome, which leads to an increase in the number of copies of the same gene contained in a cell.

Each of these violations carries certain diagnostic signs and information. For example, translocations may indicate the presence of leukemias, lymphomas, or sarcomas, and the presence of gene duplications helps to prescribe the most effective therapy.

What is the advantage of the FISH test?

Compared to traditional analyzes of the genetic material of cells, the FISH test has a much higher sensitivity. It allows you to detect even the smallest changes in the genome that cannot be detected by other methods.

Another advantage of the FISH test is that it can be used on material recently obtained from a patient. For a standard cytogenetic analysis, it is necessary to first grow a cell culture, that is, to allow the patient's cells to multiply in the laboratory. This process takes about 2 weeks, and another week is spent on conducting a routine examination, while the result of the FISH test will be received in just a few days.

The steady development of medical science is gradually leading to a reduction in the cost of the FISH test and its increasingly widespread introduction into the daily practice of oncologists.

Because the FISH test can detect genetic abnormalities that cause cancer, it is an effective method for diagnosing certain cancers. The test is also used to confirm the diagnosis and provide additional information about the possible outcome of the disease and the feasibility of using chemotherapy.

For example, in patients with breast cancer, a FISH test on tissue taken from a biopsy can help determine if the cells have copies of the HER2 gene.

Cells with copies of the HER2 gene have more HER2 receptors, which receive signals that stimulate the growth of cancer cells in the breast. Therefore, for patients with copies of the HER2 gene, it is advisable to use herceptin (trastuzumab), a drug that inhibits the ability of HER2 receptors to receive signals.

Due to the high cost and relative unavailability of the FISH test, another test for detecting breast cancer, immunohistochomy (IHC), is more often used.

There is debate in the medical community about the high performance of the FISH test compared to standard tests. However, with advances in technology, the FISH test is becoming cheaper and more affordable in a variety of clinical settings.

How the FISH test works

When performing a FISH test on a sample of patient's tissue, fluorescent labels are used that bind only to certain parts of the chromosome. Then, using a fluorescence microscope, the regions of the chromosomes with which the fluorescent probes have bound, and the presence of possible abnormalities that provoke the development of cancer, are determined.

The following abnormalities can be found in cancer cells:

• translocation - transfer of a portion of a chromosome to a new position on the same or a different chromosome;
• inversion - a turn of the chromosome section by 180 degrees while maintaining the connection with the chromosome itself;
• deletion - loss of a part of the chromosome;
• duplication - duplication of a chromosome section, leading to an excess content of gene copies in the cell.

Translocations help diagnose some types of leukemia, lymphoma, and sarcoma. The presence of a duplication in breast cancer cells helps the doctor choose the best treatment.

The advantage of the FISH test over standard cytogenetic tests (examining the genetic makeup of cells) is that it can detect even the smallest genetic changes that cannot be seen with a conventional microscope.

Another important difference of the FISH test is the ability to perform it on cells that have not yet begun to actively develop. Other tests are performed on cells only after they have grown in the laboratory for two weeks, so the whole process can take up to three weeks, and the results of the FISH test are available within a few days.

Examples of FISH test for cancer diagnosis

Although the FISH test is most commonly used to analyze genetic abnormalities in breast cancer, it can also provide important information about other cancers.

For example, in the diagnosis of bladder cancer, a FISH test on urine cells is more accurate than tests for abnormal cells. In addition, it allows you to determine the recurrence of bladder cancer 3-6 months earlier.

The FISH test can also help detect chromosomal abnormalities in leukemia, including cells indicative of an aggressive form of chronic lymphocytic leukemia (CLL). Patients with aggressive CLL may require urgent treatment, while those with less aggressive forms may require follow-up.

FISH test controversy

Not all experts agree that the FISH test is the most accurate test for diagnosing cancers susceptible to Herceptin.

In 2010, scientists at the Mayo Institute in Ireland stated that the less expensive IHC test was almost as effective in determining susceptibility to Herceptin as the FISH test.

Other experts criticize the FISH test for failing to detect small mutations, such as small deletions, insertions, and point mutations, and for ignoring some inversions.

Improving the FISH test

Despite the fact that the FISH test technology does not allow to analyze all chromosome regions yet, it is constantly developing in this direction.

For example, in 2007, Canadian scientists announced the development of a microscope slide-sized chip that would allow the FISH test to be performed using a device that fits in the palm of your hand.

Called the FISH Test on a Chip, this advanced test will get results in one day at a fraction of the cost of other tests.