Sperm DNA fragmentation - what is this analysis? Indications, explanation of the Tunel test and pregnancy prognosis

The study of sperm DNA fragmentation is a fairly relevant topic if we consider the problem from the point of view of male infertility and infertile marriages. In some cases, a classic spermogram is not enough (even with good indicators), and there is a need for additional ultrastructural research. The sperm DNA fragmentation test is just such an analysis. The analysis is done using several methods, but the most often used is the study of DNA fragmentation in sperm using the Tunel test.

• Spermatogenesis
• What is sperm DNA fragmentation
• Causes
  • Predisposing factors
• What is the effect of chromatin damage?
• Sperm DNA fragmentation test
  • Decoding
• High fragmentation index and recurrent miscarriage
• How to reduce sperm DNA fragmentation
  • Surgical treatment of varicocele
  • Oral antioxidants
• Who should take the test “Spermogram with DNA fragmentation in sperm”
• The essence of the study
• Preparing for the test

What is physiological fragmentation of sperm DNA in spermatogenesis

In the human body, the sperm is the smallest cell. To reduce its size during spermatogenesis (sperm maturation and transformation into mature sperm), a specific transformation occurs. The nucleus is compacted due to the mechanism of chromatin condensation. Most of the cytoplasm is “thrown out” from the male germ cell in the form of a “cytoplasmic drop”, only the necessary organelles remain.

Schematic representation of DNA packaging into a chromosome

Histone proteins are required to assemble and package DNA strands into chromosomes. Histones are removed from the nucleus of the future sperm, and DNA binds to protamine proteins. This allows the chromatin to condense tightly and reduce the size of the sperm nucleus. At this time, DNA sections “unwind” and at the maturation stage they should connect again, but this does not always happen. For some sperm, this process remains incomplete - this is the physiological fragmentation of sperm DNA. In healthy men, the degree of fragmentation does not exceed 15%.

Pathological fragmentation of sperm DNA - what is it?

In infertile men, the sperm index with impaired chromosome integrity is more than 30%. When sperm DNA fragmentation is more than 30%, the probability of pregnancy is extremely low, and early pregnancy losses are high (fading, spontaneous abortions, etc.).

Causes of DNA fragmentation

There are 2 groups of causes of impaired chromosome integrity in male germ cells:

1. Internal defects of spermatogenesis (developmental anomalies and genetic defects).
2. External damage to the testicles (indirect effects of gonadotoxins, hyperthermia, oxidative stress, endocrine diseases).

These cases are directly affected by protamine deficiency, reactive oxygen species, disruption of apoptosis mechanisms, disturbances in the replacement of histones with protamines in spermatids, poor chromatin packaging, and increased sensitivity to oxidative stress of defective spermatozoa.

Factors leading to sperm DNA fragmentation

An increase in the degree of DNA fragmentation leads to:

• leukospermia – increased number of leukocytes (inflammatory processes, hidden sexually transmitted infections);
• age after 35 years;
• habits or lifestyle: alcohol, smoking;
• external factors: pesticides in food, work in chemical production, increased temperature in the workplace, exposure to radiation;
• neoplastic pathologies: leukemia, lymphoma, testicular cancer and chemotherapy;
• pathological processes: increased body temperature, varicocele, genital infections, testicular torsion, cryptorchidism, weak spermatogenesis.
• genetic factors: DNA repair disorders, antioxidant genes, detoxification pathway, aberrations and microdeletions.

What is the effect of chromatin damage in male germ cells?

Increased percentage of sperm DNA fragmentation:

• reduces the fertile reproductive potential of a man;
• reduces the frequency of pregnancy;
• increases reproductive and natural fertilization, especially in the early stages;
• reduces the effectiveness of ART programs (unsuccessful IVF and IUI).

In addition, altered DNA leads to chromosomal abnormalities in children, reduces the life span of offspring, and contributes to the development of congenital genetic defects in children.

Analysis (test) for sperm DNA fragmentation: evaluation of results and decoding Tunel test

There are several methods for determining the DNA fragmentation index:

• Tunel;
• Halosperm;
• SCSA.

The most prognostically significant is the study of DNA fragmentation in sperm using the Tunel method, but Halosperm is more economically profitable. The test is most often carried out using the Tunel and Halosperm methods.

The breakdown of DNA fragmentation in the spermogram is presented in Table 1.

Table 1. Fragmentation index

Fragmentation level	Decoding and recommendations
0-15%	Norm. Natural pregnancy seems possible
15-25%	Natural pregnancy is possible, but the wait may be longer. If, intrauterine insemination is recommended. If at the same time a woman has pathologies in the reproductive sphere, she should.
> 30%	Pregnancy is unlikely; the chances will increase if you resort to in vitro fertilization.
>50%	Pregnancy is unlikely when using IVF. Recommended.
>60%	The chances are very small, the only option is either.

Sperm DNA fragmentation and recurrent miscarriage

• idiopathic infertility (when the cause is unknown);
• after multiple unsuccessful IVF attempts;
• obtaining embryos of low quality in the IVF protocol;
• habitual miscarriage and repeated miscarriages;
• varicocele;
• men over 45 years old;
• after (for: it is necessary to ensure that the percentage of cells with damaged DNA does not exceed the norm);
• high temperature observed in the last 3 months.

The pathophysiological processes leading to DNA damage are not fully understood. A specific treatment regimen for infertility caused by this factor has not yet been developed. And methods of reproductive medicine do not always achieve positive results. But normalizing the DNA structure of sperm can improve and increase the frequency of clinical pregnancies.

The essence of the Tunel method

To carry out the sperm test. A portion of the biomaterial sample is used for light-optical examination, where the morphological qualities of sperm and the composition of sperm are assessed. The part is examined using the Tunel method.

To assess fragmentation, a solution of labeled fluorescent nucleotides that are capable of binding to fragments of DNA strands is added to the sample to assess fragmentation. Nucleotides are inserted into the broken chain and act as tags that fluoresce under a microscope. Then the percentage of “labeled” sperm is calculated and the result is displayed.

How to prepare for research

Before collecting biomaterial, the same requirements apply as before:

• Sexual abstinence for at least 2 and no more than 7 days. The best time is 3 days. If the test is repeated, it is better that the abstinence intervals are the same.
• Refusal of alcohol, smoking, overheating (saunas, baths, etc.) for a period of 3 months (the entire process of spermatogenesis lasts on average 72 days).
• Stop taking any medications unless otherwise indicated by your doctor and there is no threat to life due to interruption of therapy.
• If a man has suffered from ARVI, influenza and other diseases with an increase in body temperature, the test must be rescheduled.
• Avoid physical and emotional stress the day before.

The entire preparation period requires proper nutrition and drinking regime (1.5-2 liters per day).

It is necessary to understand that the qualitative characteristics of male germ cells change over time, unlike female ones. Therefore, the accuracy of the results depends on how seriously you take the preparation and treatment (for a repeat fragmentation test).

Sperm DNA fragmentation is an indicator that began to be studied relatively recently. However, such a study became a real revolution in the field of determining the causes of male infertility. The analysis helps determine the usefulness of the genetic material in sperm; it requires special reagents, as well as good technical equipment in the laboratory, so the cost of such a study is quite high. In this article we will discuss the essence of the analysis, its price, conditions for collecting material, and a possible interpretation of the results obtained.

Difference from spermogram

Many people are accustomed to believing that the presence or absence of infertility is determined by a spermogram. In fact, the indicators it displays are very different from fragmentation analyses. The spermogram reflects the qualitative and quantitative composition of the ejaculate, its volume, and physical characteristics. DNA tests determine the number of sperm that carry high-quality genetic material, and therefore the number of germ cells capable of forming a full-fledged zygote with an egg.

In some sources, these studies are presented as “spermogram DNA fragmentation.” This name is considered erroneous, since DNA analysis has no relationship with spermogram. Even the collection of material is carried out for each study separately.

Purpose of the study

Fragmentation of sperm DNA is the process of breaking the DNA strands that are contained inside its head, performing the main role of the germ cell - the transfer of genetic material. This process is considered pathological because it affects the possibility of conception, normal development of the embryo, and the success of bearing a child.

Fertilization of an egg with a fragmented sperm actually does not produce a normal zygote, and if conception occurs, then problems begin with the attachment of the placenta and the development of the embryo. As a result, miscarriages often occur.

Who is it shown to?

A fragmentation test is taken when it is impossible to objectively determine the reason for the absence of children in a couple using conventional tests. Reasons for research may also include:

• Causeless infertility.
• Multiple miscarriages.
• The man's age is after 45 years.
• Preparation for the IVF or ICSI procedure.
• Poor indicators of cell morphology, reflected by the spermogram.

The study should be carried out for varicocele.

Types of tests

You can get tested for sperm DNA fragmentation in private clinics, laboratories, and also in family planning centers. Considering that various methods are used to carry out the test, patients have to choose, but the result of the choice is often influenced not by the essence or effectiveness of the technique, but by the price of the study.

The Halosperm test is a test of sperm chromatin. This test does not display existing violations of the DNA structure, but the tendency of the chains to denaturalize, so the predictive ability of this test cannot be called high enough. Its price is about 4500-5000 rubles.

The TUNEL test is an innovative technique for testing sperm for DNA fragmentation. By mixing a special enzyme with the material under study and then examining it under a microscope, it is possible to analyze the ratio of fragmented cells to healthy ones. The difference is immediately visible, since the fragmented sperm appears clearly a certain color, and a healthy cell distributes the enzyme both within itself and around it.

The results of the TUNEL test have a high predictive ability. The technique itself is considered to be as accurate as possible for such studies. The price of the analysis is approximately 10,000 rubles, although some laboratories offer a reduced price - 7,500-8,000 rubles.

How to collect material?

A man needs to prepare for a test for germ cell fragmentation in the same way as for a spermogram, namely:

1. Observe sexual rest for three days.
2. Avoid baths, hot showers, and tight underwear.
3. Avoid the use of alcohol, nicotine, and medications.

Where to collect the material is decided by the patient himself, but it is better to give preference to laboratory conditions in order to preserve the purity of the material, as well as its integrity, because when the temperature outside is -30°C, it is extremely difficult to avoid freezing of the container. Exposure to high or low temperatures may result in inaccurate data.

Before taking tests, you should avoid baths and hot showers.

The instructions for collecting sperm for analysis of fragmentation and spermogram are the same: you need to achieve ejaculation manually, place the seminal fluid inside a sterile plastic container without touching its inner walls, and submit it for examination within an hour after collection.

Having passed the analysis once, you need to be prepared to take it again, because the indicators after a certain period of time may differ due to the elimination of the cause of fragmentation or changes in living conditions. Most often, men over 30 who have bad habits are tested again.

How to read results

The patient receives the test results in person, so he has the opportunity to examine the indicators independently. The level of sperm DNA fragmentation is displayed as a percentage and is deciphered as follows:

• Up to 15% – natural fertilization is possible.
• 15-25% – natural fertilization is difficult.
• Fragmentation exceeded 30% - an indication for IVF.
• The number of sperm with DNA breaks exceeded 50% - an indication for ICSI.
• Fragmentation greater than 60% is an indication for the use of donor material.

Fragmentation in healthy men usually does not exceed 15%. Even if a fragmented sperm enters the egg, it can independently restore the damaged structure of its DNA. The best ability to do this is preserved in young expectant mothers. It is worth noting that with fragmented DNA in sperm up to 30%, natural fertilization is considered possible, but it can take quite a long time, so it is better for the couple to be patient.

If the indicator exceeds this threshold, then it is better to resort to artificial insemination methods. The ICSI technique allows you to select a sperm for fertilization with a normal DNA structure, which reduces the risks of miscarriages or abnormal development of embryos.

As can be seen from the material presented above, a spermogram is not always enough to accurately determine the cause of a couple’s infertility. Thanks to the development of science, it is now possible to determine in advance a man’s ability to conceive a child normally, and also to take the necessary measures in the event of a violation or loss of this opportunity.

Statistics show that in a number of countries the prevalence of infertility is 8-29%, and worldwide - 15%. At the same time, every eighth couple fails to conceive their first child. Every sixth couple experiences difficulties with the birth of their second and subsequent children. In half of the cases, this is due to problems of the stronger sex, that is, with altered parameters of the male seed, which is also called “DNA fragmentation.” Over the past two decades, this trend has only increased: from 30 to 50%.

If necessary, do an appropriate analysis to determine the degree of DNA fragmentation. But not every man is familiar with this term, and he may have many questions. Therefore, it is worth deciphering it in more detail.

What does the term "DNA fragmentation" mean?

This definition refers to the degree of damage to the DNA chain, which is an indicator of the quality of germ cells and indicates the level of fertility of a man. Breaks lead to the fact that the integrity of genetic information is violated. As a result, the likelihood of having a child is significantly reduced.

Often, DNA fragmentation occurs due to a decrease in protamines. These are special transport proteins that are contained in chromosomes. They perform the main protective function - they prevent damage to the DNA chain under the influence of external factors.

The presence of DNA fragmentation in germ cells has a direct impact on the early maturation of the embryo and the formation of the blastocyst. Typically, spermatozoa, even with a high degree of fragmentation, are capable of fertilizing female germ cells, but subsequently, at an early stage of embryo development, the process may stop.

Causes of pathology

Violation of genetic information in sperm can be caused by various factors, which are both internal and external in nature. can occur due to numerous disorders of different body systems, such as:

• sexual;
• endocrine;
• nervous;
• circulatory;
• immune, etc.

The main task of the male reproductive cell is to deliver healthy material to the egg without any damage. Only in this case, after fertilization of the latter, the embryo will develop fully and normally. Otherwise, there may be various pathologies. What causes DNA fragmentation?

Internal reasons

There are two reasons for internal factors. The first of them is the defective development of seminal fluid. The maturation of male germ cells occurs in the epididymis. At this time, chromatin, which is located in the cell nucleus, is activated. It is he who is responsible for sperm motility. In some cases, the procedure may go wrong and the DNA helix becomes damaged.

The second internal factor is the incorrect rejection of germ cells. The birth of sperm occurs in the testes. The peculiarity of the male body is the ability to determine the state of the germ cells. If spermatozoa exhibit certain genetic abnormalities or differences in their structure, the body itself gets rid of them. But sometimes the culling process itself goes wrong. In this case, the ejaculate will contain both healthy cells and damaged ones.

External reasons

In addition to internal reasons, fragmentation of cell DNA can occur due to a number of these include the presence of certain diseases that occur in acute or chronic form. The destruction of germ cells can be caused by inflammation of the genitourinary system. This is especially true in cases where any disease has not been completely cured.

Often the cause is such a common disease among men as varicocele. Usually, pathology is easy to detect by dilation of the veins in the testicles. But a more accurate diagnosis will be established by appropriate examination. But besides this, the reasons may be:

• high fever for a fairly long period of time, in the absence of obvious signs and symptoms;
• the presence of oxidative stress;
• X-ray irradiation;
• undergoing chemotherapy;
• bad habits.

Regarding the last point, sperm DNA fragmentation occurs due to smoking.

Currently, there are many ways to combat this bad habit. And if you want to raise children, you should completely abandon it. And the sooner the better!

Standard diagnostics - spermogram

To give birth to a fully healthy child, you need good hereditary material. And to determine the condition of male reproductive cells, a standard analysis of the ejaculate is performed. The result of such a study will show the probable causes of fertilization disorders. A spermogram also allows you to determine the structure, concentration, degree of mobility of male germ cells, and at the same time check them for compliance with the physiological norm. The analysis also includes determining the acidity of seminal fluid.

In addition, this study allows you to determine the number of leukocytes, which normally should not be more than one million per milliliter of semen. An important parameter is color and smell. A healthy one has a white, cream or slightly pink tint, and the smell resembles a chestnut. If there are any abnormalities, a more thorough examination is required, the decision on which is made by the attending physician based on the results obtained.

However, experts believe that standard analysis cannot determine whether DNA fragmentation has occurred. Examination methods simply do not allow this to be done, since a spermogram mainly determines only the physical parameters of seminal fluid. Therefore, it is impossible to diagnose a DNA chain using this method, and experts recommend using another common technique called TUNEL.

The essence of the TUNEL technique

Many experts recommend studying the DNA chain using this particular technique. The study allows you to determine the number (in%) of damaged germ cells. Based on the results, you can select the necessary treatment methods in order to increase male fertility.

After donating the ejaculate, special reagents are added to it, and further examination takes place using a microscope. At the same time, the number of healthy and damaged sperm is clearly visible. An experienced researcher will quickly and accurately detect DNA changes. Sperm fragmentation in this case is manifested in the fact that the damaged germ cells differ significantly in appearance.

The result of the study is given only by a qualified specialist to the patient in the form of a photograph depicting cells. An important examination parameter is the percentage of healthy cells to fragmented ones. Normally, the number of damaged cells does not exceed 15%.

Passing the examination involves a number of mandatory rules. For seven days, do not take a hot bath and avoid going to the bathhouse. During this period, you should abstain from sexual intercourse and stop drinking alcohol. Sperm is collected directly on the day of the procedure in a special plastic container. This can be done both at home and in a medical facility.

When should you start worrying?

Many men not only have no idea what DNA fragmentation is, the rate of this indicator is also unknown to them. As well as at what point you need to undergo an examination. For this reason, there is an increase in infertility and the occurrence of various diseases. In this regard, it is worth citing cases when you should think carefully:

• A family cannot conceive a child for a long period of time.
• There have been several attempts at artificial insemination in the past.
• Unsatisfactory condition of the embryo.
• Your beloved significant other experiences frequent cases of miscarriages, but this is clearly not the case with her.
• The man is 45 years or older.
• The presence of varicose veins of the spermatic cord.
• A man has had a fever for three months or more.

As for the first case, women often undergo an examination, during which it turns out that they are completely healthy, but pregnancy does not occur. In this case, men should also be examined.

An examination for germ cell fragmentation is prescribed by a personal attending physician and only under certain circumstances.

Where can I get tested?

Now we know what DNA fragmentation is, “where to donate” is the next question that may arise. Currently, almost any laboratory with modern equipment is engaged in the study of male semen. You can get tested at almost any government medical institution free of charge. Just waiting for the result may take several days. When contacting one of the private laboratories, the result will be available within one day.

It is worth remembering that each study differs in its results. Therefore, for reliability, it is better to take several tests in a row. This is the only way a doctor can put everything together and make an accurate diagnosis.

Improving the degree of fragmentation

Until a certain point in time, it was impossible to change the rate of DNA fragmentation for the better. But after recent research, the opposite was proven. Reducing fragmentation is achieved by introducing antioxidants into the patient's body. But in some cases, sperm DNA fragmentation analysis does not confirm a positive result.

For example, if changes in cells are caused by prolonged exposure to high temperature or toxic substances.

Beneficial properties of folic acid

After scientists analyzed the diet of many men, they came to one interesting conclusion. The higher the amount of folic acid in food, the fewer abnormal cells are formed. Therefore, 3-4 months before planning pregnancy, you should include acid in your diet, which is found in various foods. Among the plant products are:

• greenery;
• cereals, legumes;
• bananas;
• citrus;
• carrot;
• nuts.

Acid is also found in products of animal origin:

• liver and meat of beef, pork and lamb;
• salmon;
• egg yolk.

It is also present in dairy products.

When cooking some products, the loss of acid is up to 90%. Therefore, if possible, it is better to consume them raw. By including these foods in your diet, you can be sure that the DNA fragmentation test will show a positive result. This means that you won’t have to worry about the health of your unborn baby.

ASSESSMENT OF SPERM DNA DAMAGE

Damage to sperm DNA means loss of structural integrity of the entire sperm DNA molecule.

The term “sperm DNA damage” refers to many defects in chromatin structure, including breaks of one or two helices of the DNA molecule, deletions or modifications, the formation of additional bonds in the helix or between DNA helices, and incorrect placement of protamines due to defective DNA cross-linking and proteins.

Chromatin damage can occur at any stage spermatogenesis, spermiogenesis, when passing through epididymis, and in vitro - during the preparation of sperm for artificial insemination.

Defective sperm containing damaged DNA retain the ability to fertilize. However, some forms of infertility are associated with such DNA damage, such as idiopathic infertility, repeated failures of intrauterine insemination (IUI) and IVF, and recurrent miscarriages. Moreover, damage to sperm DNA is associated with an increased risk of cancer and passed-on defects in the offspring.

Of the many suspected causes of sperm dysfunction today, nuclear DNA damage is the most studied and increasingly recognized as a key factor influencing embryo quality, development and implantation. You can take a DNA fragmentation test daily at the Clinical Andrology Laboratory.

Cost of DNA fragmentation analysis:

Damage to sperm DNA is associated with spermogram parameters: a decrease in concentration, motility and the proportion of normal forms of sperm. At the same time, in 10-20% of cases they can occur with “normozoospermia”.

The leading cause of DNA damage is oxidative stress of sperm, caused by excess production of reactive oxygen species (see figure from Aitken RJ et al., 2014).

Another reason is incomplete apoptosis of sperm, associated with disorders of spermato- and spermiogenesis, and/or elimination of defective forms in the epididymis.

ByAitken RJ et al. // Asian J Androl.2014, 16 (1): 31.

Damage to sperm DNA is a multifactorial process, depending on both genetic predisposition and external damaging factors (smoking, overheating, toxic substances, etc.).

Since this can have several causes, assessment of fragmentation, oxidative stress and chromatin packing disorders are especially recommended for:

couples with a history of miscarriages;

couples with unexplained infertility for more than 6 months;

men over 40 years old;

patients with varicocele;

patients with systemic diseases (diabetes, obesity, etc.);

men with harmful lifestyle factors (smoking, ionizing radiation, toxic substances, overheating, including when using tight-fitting clothing, unbalanced diet, etc.);

men with a history of cancer and chemotherapy;

men taking certain prescription drugs;

in men who have had urogenital infections;

poor embryo quality during repeated egg donation cycles;

male idiopathic infertility.

To detect DNA damage in spermatozoa, various methods are used: chromatin dispersion in agarose gel (SCD), DNA electrophoresis after denaturation (COMET), terminal labeling (TUNEL), etc.

In the table we have summarized the principles and interpretations of the most widely used tests.

Method	Presearch principle	Dimension of the results obtained	Normal values
TdT-mediated DNA strand break dUTP end labeling method (TUNEL method)	Measures the extent of DNA damage by inserting a DNA probe (modified nucleotide) into the site of DNA damage	Proportion of sperm with DNA damage that carry a modified nucleotide inserted into a DNA break	Less than 20%,
Sperm chromatin structure analysis (SCSA method)		Number of sperm with fragmented DNA in %	Less than 30%
Analysis of sperm chromatin dispersion (SCD method)	Measuring the susceptibility of DNA to denaturation	Number of sperm with fragmented DNA, %	Less than 15%
DNA comet method (COMET)	Measuring the susceptibility of DNA to denaturation	The degree of DNA fragmentation in an individual sperm is assessed by the proportion of DNA in the comet tail, tail length and color intensity	Undefined
Staining with aniline blue and chromomycin A3	Measuring the level of sperm chromatin compaction based on the ratio of histones and protamines	Number of sperm with low chromatin compaction, %	Less than 30% IndexG0+G1+G2x2 less than 40

To assess DNA fragmentation, the SCSA method was historically the first to be used more than 35 years ago. For scientific purposes, the most commonly used method is TUNEL, which is capable of detecting both single-strand breaks and double-strand breaks in DNA. The most modern and convenient for clinical use is the SCD method; some also consider it the most sensitive.

Condensation (packaging) of sperm chromatin is assessed by the ratio of histone and protamine proteins in sperm, for which staining with aniline blue and chromomycin is used

Original photos from our laboratory:

A- TUNEL; B- SCD; B-histones/protamines

The detection of increased sperm DNA fragmentation requires treatment aimed at eliminating the supposed pathogenetic factor: infectious and inflammatory processes, and even asymptomatic carriage of infections such as Chlamydia trachomatis, Mycoplasma sp., Ureaplasmaurealyticum, some serotypes of E. coli, etc., testicular overheating (in including those associated with varicocele), smoking, the effects of certain medications (paroxetine, miloxan, pentoxyphylline, etc.), excess weight, impaired carbohydrate metabolism, etc. If oxidative stress is detected, additionally use various antioxidant nutrients. In the most difficult cases, it may be useful to obtain sperm directly from the testicles, where they are protected from the action of active radicals blood-testis barrier. But in this case, subsequent failures of IVF ICSI may be associated with a violation of chromatin packaging, since the replacement of histones with protamines, necessary for the full maturation of sperm, occurs already in the epididymis.

In recent years, modern cellular technologies have been used quite effectively to normalize the structure of sperm chromatin, incl. associated with the use of MSCs and Sertoli cells.

Doctor med. Sciences, Professor V.A. Bozhedomov

A few quotes about the significance of sperm DNA fragmentation:

“...DNA damage increases in the sperm of men with oligozoospermia. This increase is associated with a decrease in the chances of natural pregnancy and an increase in the likelihood of early pregnancy loss..."

Male Infertility / A. Jungwirth (Chair) et al. ©

European Association of Urology, 2017: 14.

“...There are two types of sperm DNA fragmentation, one of which depends on the parameters of the spermogram, and the second does not...”

Muratori M. et al.// Hum. Reprod., 2008, V23 (5), p.1035-1043.

“...Defective sperm containing damaged DNA retain the ability to fertilize. However, several infertility phenotypes are associated with such DNA damage, such as unexplained and idiopathic infertility, repeated failed IUI and IVF, and recurrent miscarriages. Moreover, damage to sperm DNA is associated with an increased risk of cancer and transmitted defects in the offspring..."

Sperm chromatin: biological and clinical application in male infertility and assisted reproduction / A.Zini, A.Agarwal (Ed.), 2011, Springer, 512.

“...Of the many causes of sperm dysfunction currently hypothesized, nuclear DNA damage is the most studied and increasingly recognized as a key factor affecting embryo quality, development and implantation...”

Mallidis C. et al.// Hum Reprod., 2010, V.26, N7, P.1641-1649

“...Spermatozoa with fragmented DNA can fertilize mature oocytes, but paternal genome activation can disrupt embryonic development, leading to preimplantation and postimplantation losses. This type of damage can occur in embryos with normal chromosomal complement and may explain why some embryos with normal karyotypes fail to produce pregnancies in patients with unexplained miscarriages. In general, the greater the degree of DNA damage transmitted to the embryo by the paternal genome, the earlier this damage will become apparent during embryonic development..."

Bareh Gihan M. et al. // Fertility and Sterility, 2016, 105 (2): 15-282

“...Recent studies have shown the importance of sperm DNA integrity as an important factor that influences the functional competence of sperm. Therefore, detection of sperm DNA fragmentation may be clinically useful as part of the fertility assessment process... Sperm DNA fragmentation tests have virtually no difference in predictive value between IVF and ICSI..."

Cissen M et al. Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis. PLoS One. 2016 Nov 10; 11(11):e0165125.

“...Current animal models and extrapolated data from human studies raise concerns about health problems in sperm-derived offspring with increased levels of DNA fragmentation...”

Bach PV, Schlegel PN. Sperm DNA damage and its role in IVF and ICSI. Basic Clin Androl. 2016, 5 (26): 15.

“...The unique process of chromatin compaction in sperm has important implications both for the development of screening tests for male infertility and for understanding the characteristics of sperm chromatin that may influence the results of assisted reproductive technologies...”

Palermo GD et al. Perspectives on the assessment of human sperm chromatin integrity. Fertil Steril. 2014 Dec; 102(6):1508-17.

“…A bivariate random effect meta-analysis yielded an AUC (area under the curve) of 0.92 with a sensitivity (95% confidence interval) of 0.80 (0.78-0.82) and specificity of 0.83 (0.80-0.82). 86) for the use of the SDF test in differentiating infertile men from normal fertile controls. Moreover, subgroup analysis showed that the SDF analysis with the TUNEL test alone resulted in an AUC value of 0.9506 with a pooled sensitivity of 0.77 (0.74 - 0.8) and specificity of 0.91 (0.87 - 0.94), while the SCD and Comet tests displayed a pooled sensitivity of 0. 77 (0.67-0.81) or 0.91 (0.88-0.94) and specificity 0.84 (0.75-0.91) or 0.63 (0.54-0.70) , accompanied by an AUC value of 0.84 or 0.94..."

Cui ZL et al. Diagnostic Accuracies of the TUNEL, SCD, and Comet Based Sperm DNA Fragmentation Assays for Male Infertility: a Meta-analysis Study. Clin Lab. 2015; 61(5-6): 525-35.