The Impact Of Sperm Factor On Unexplained Recurrent Pregnancy Loss

Background: Recurrent pregnancy loss (RPL) affects approximately 0.5-1.0% of married couples who trying to conceive and they suffer much. Many factors can cause RPL. Greater than 50% of cases remain unexplained, even after an extensive investigation. The medical evaluation of recurrent pregnancy loss to date has focused mainly on the female, without much consideration of the male. However, the male gamete contributes one-half of the genomic content to the embryo. Genetic disorder of sperm may impact embryonic development and maybe result in pregnancy loss. Studies indicated that sperm chromosome aneuploidy is related to RPL, and some researchers found that sperm DNA integrity is significantly poorer in the URPL (unexplained recurrent pregnancy loss) group than in the control by TUNEL and AOT (acridine orange test) analysis.Objective: In order to further study the impact of sperm on URPL, and explore mutations which may exist in the cases of the poor DNA integrity.Methods: We collected the semen of 21 URPL patients as study group, and 20 proven fertility men as control group. We evaluated sperm chromosome aneuploidy for chromosomes 18,X and Y using multi-color FISH (fluorescence in situ hybridization) procedures, and sperm DNA integrity using SCSA(sperm chromatin structure assay) procedures. And according to the knockout studies, we screened the mutations of Tnp1 and Tnp2 genes in eight patients whose DFI values beyond 27% by using PCR-DHPLC (denaturing high performance liquid chromatography) -sequencing method,Results: (1) In the RPL group, compared with the control groups, no differences were observed in the sperm routine parameters, but the percentage of normal morphologic sperms was diminished, the DFI value was increased, but HDS (high DNA stainability) value showed no significant difference. The percentage of sperm aneuploidy for chromosomes X, Y, and 18 was significantly higher in the recurrent pregnancy loss group.(2) All the detective areas demonstrated single normal peak type, no mutation was identified in these eight patients.Conclusions : (1) Sperm morphology, DNA integrity and chromosome aneuploidy is correlated with recurrent pregnancy loss, so we suggest that these factors should be included in the evaluation of these couples in the future.(2) The results suggested that sperm DNA damage may be multi-factor process.