Etiology and Evaluation of Sperm Chromatin Anomalies

Evidence suggests that human sperm chromatin anomalies adversely affect reproductive outcomes and infertile men possess substantially amount of sperm with chromatin anomalies than fertile men. Routine semen analysis evaluates parameters such as sperm motility and morphology, but does not examine the nuclear DNA integrity of spermatozoa. It has been suggested that altered nuclear chromatin structure or damaged DNA in spermatozoa could modify the special cellular functions of human spermatozoa, and thereby affect the fertility potential. Intra-cytoplasmic sperm injection (ICSI) bypass the barriers to fertilization for such a sperm, then the effect of chromatin anomalies on the development remains a concern. Therefore, it is essential to develop and use accurate diagnostic tests, which may provide better prognostic capabilities than the standard sperm assessments. This review discusses our current understanding of the structure and organization of sperm DNA, the different procedures for assessment of sperm chromatin anomalies including comet assay, Chromomycin A3 (CMA3), sperm chromatin structure assay (SCSA), acridine orange test (AOT), terminal TdT-mediated dUTP-nick-end labelling (TUNEL) assay, aniline blue and sperm chromatin dispersion (SCD) test and the impact of chromatin anomalies on reproductive outcome.