SPERM DNA FRAGMENTATION: ASSAYS and CLINICAL IMPLICATIONS

In the latest years, interest in sperm DNA alterations and their correlations to either spontaneous or ART-induced pregnancy rate has been increasing more and more. Compared to conventional semen analysis, DNA fragmentation (SDF) evaluation could offer more accurate information about male fertility, because its biological variability seems very low. The available assays are direct or indirect. The former, by means of probes or dyes, can directly measure SDF (COMET, TUNEL); the latter estimates SDF indirectly, measuring denaturation susceptibility, which is higher in fragmented DNA (SCD, SCSA, Acridine Orange stain [AOS], Aniline Blue staining [ABS]). Although some studies have found some value in the use of sperm DNA tests in the evaluation of male infertility, the true prognostic value of sperm DNA assessment to predict ART outcomes remains uncertain. Despite all these limitations, however, many studies have pointed out that high SDF levels are associated with a lower pregnancy rate in natural conceptions and after IUI and IVF, and a higher miscarriage rate after ICSI; direct methods may have a higher predictive value of pregnancy outcome. However, in order to provide clinically valid scores, every SDF test requires at least a critical number of sperm cell. TUNEL test seems able to maintain validity even when performed on a low sperm cell number (~200) ; therefore, TUNEL might be useful to determine whether cryptozoospermic patients should perform ICSI with either testicular or ejaculate spermatozoa. Even with all ambiguities, it has been demonstrated that SDF has an impact on natural pregnancy and ART outcomes. More studies can help us to clarify more unknownaspects of the SDF, particularly about which test or tests are much more useful in diagnosis and treatment of infertility.

کلیدواژه ها:

DNA fragmentation tests ، semen ، ART ، male infertility