The predictive value of sperm chromatin structure assay

Sir, I read with great interest the Letter to the Editor by Nicopoulloset al. (2005) entitled ‘The predictive value of spermchromatin structure assay’, published in the March issueof Human Reproduction, and also the replies by Bungum (2005),Check and Johnson (2005) and Gandini (2005). Perhaps, before discussing the predictive value of the spermchromatin structure assay (SCSA) test in assisted reproductivetechnologies, it would be useful to review the causes and typesof DNA damage found in human sperm and the different tests thatcan be used to assess this damage. DNA damage in sperm can affect both mitochondrial and nuclearDNA and can be induced by five main mechanisms: (i) apoptosisduring the process of spermatogenesis; (ii) DNA strand