Relationship of DNA integrity to C633T SNP and ART outcome in infertile couples.

The status of sperm DNA fragmentation, protamine deficiency, free thiols and disulphide bonds in colloid-selected samples and its relationship to ART outcome or C633T SNP is not known. The objective of this study was to determine these relationships in spermatozoa from men with male factor or unknown factor infertility ( = 118) undergoing fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). Sperm DNA integrity was analysed by flow cytometry using three fluorescent probes (acridine orange, monobromobimane and chromomycin A3). Principal component analysis (PCA) was used to identify the parameters that most influenced fertility. The relationships of sperm DNA integrity with seminal parameters, C633T SNP and ART outcome were established using ANOVA and -test. Sperm concentration and yield after preparation accounted for 27% of the total variance; sperm DNA integrity (%DFI and disulphide bonds) accounted for 16% of the variance in men from infertile couples. Sperm %DFI was significantly higher ( < 0.05) in older men than in younger men. A significant difference ( < 0.01) was observed in %DFI between smokers and non-smokers. Sperm %DFI was significantly higher ( < 0.01) in male factor infertility compared to either female factor or unknown factor infertility while free thiols were significantly higher ( < 0.01) in unknown infertility factor. No significant difference was observed between IVF success/failure in any of the seminal parameters studied. There was a tendency for protamine deficiency to be higher and disulphide concentration to be lower in men with 633T. Such assessments may provide additional useful information about the prognosis for ART outcome, although more research is needed before clinical guidelines can be provided.