Methods to assess sperm DNA fragmentation

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Article by Dr. Han Thi Thu Huong - Medical Genetics Division, Vinmec High-Tech Center
Sperm DNA fragmentation assessment test (SDF-Sperm DNA fragmentation) is a technique used to measure DNA breaks in sperm nucleus. High sperm DNA fragmentation index can affect fertility by interfering with fertilization, early embryo development, implantation and pregnancy.

1. Infertility in men

According to statistics, more than 15% of couples worldwide experience fertility problems and 50% of these are due to male infertility.
Semen analysis is the most important test for evaluating male infertility, but it does not provide information regarding all sperm functions, nor is it sufficient to predict male fertility gender and success of assisted reproductive technology (ART).
In fact, about 15% of male infertility patients have normal semen analysis results. Research into new test methods for evaluating sperm abnormalities has been ongoing for more than 30 years, and sperm DNA integrity has become an area of ​​greater interest.
Sperm DNA binds to protamine and exists naturally in a solid state, protecting it from damage during transport. Some possible damage such as DNA breaks can be repaired in the egg's cytoplasm. However, when the damage exceeds the cytoplasmic threshold of repair, infertility can result.

2. Sperm DNA fragmentation assessment test

Both in vitro and in vivo studies have shown that sperm DNA integrity is negatively associated with fertility. Sperm DNA fragmentation (SDF-Sperm DNA fragmentation) test is a technique used to measure DNA breaks in the sperm nucleus. High sperm DNA fragmentation index can affect fertility by interfering with fertilization, early embryo development, implantation and pregnancy.
Currently, methods used to measure sperm DNA damage include:
Evaluation of the quality of sperm chromatin encapsulation (staining method using methyl green, aniline blue, toluidine blue). , and chromomycin A3) Evaluation of sperm nuclear DNA integrity (TUNEL, ISNT, SCSA, SCD, Comet). Direct assessment:
TUNEL (Terminal transferase dUTP nick end labeling): Evaluation of sperm DNA fragmentation through dUTP (deoxyuridine triphosphate) attached to single and double stranded DNA by terminal deoxynucleotidyl transferase. DNA fragmentation was quantified by flow cytometry and analyzed qualitatively via fluorescence signal or optical microscopy. This test can be performed on a small amount of sperm (<=200 sperm), sperm obtained from the testicle can also be evaluated for fragmentation by this technique. ISNT (In situ nick translation): A variant of the TUNEL technique for the quantification of labeled dUTPs attached to single-stranded broken DNA via DNA polymerase. Indirect assessment:
SCSA (Sperm chromatin structure assay): Evaluation of sperm fragmentation based on differential fluorescence of the fragment DNA fragment and intact DNA fragment with Acridine orange (AO), and measured by flow cytometry. AO bound to double-stranded DNA will fluoresce green at 515-530 nm and AO bound to single-stranded will fluoresce red at 630 nm. Comet (Single cell gel electrophoresis): Evaluation of single- and double-stranded DNA fragmentation based on electrophoresis. The fragmented DNA image is shaped like a comet with intact DNA at the head and broken DNA at the end. The higher the amount of damaged DNA, the brighter and longer the comet-shaped electrophoresis tail. SCD (Sperm chromatin dispersion): Evaluation of fragmentation based on characterization of halo formed from sperm nuclear protein removed after acid denaturation. Sperm nucleus with severely damaged DNA will result in a very small halo or no halo formation, while sperm with less damaged DNA will disperse the circular DNA and form a large halo. To better understand the methods of assessing sperm DNA fragmentation, customers can directly go to the nearest Vinmec Health System hospital for a more thorough consultation by a specialist. In addition, Vinmec International General Hospital has implemented an advanced and basic pre-marital examination package, with many tests using modern equipment as well as a team of experienced doctors. give young families the best preparation.

Couples before marriage should have a health check-up for the following purposes:
Fertility and sexual health assessment, screening for sexually transmitted diseases, screening for genetic diseases, counseling reproductive and contraceptive measures (if necessary) for couples before getting married. Early detection of the cause can lead to infertility and infertility. Advice on the best time to give birth and measures to give birth to healthy and intelligent children for couples preparing to have children.

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References: Gi Young Kim. What should be done for men with sperm DNA fragmentation?. Clinical and Experimental Reproductive Medicine, v.45(3); 2018 Sep.