Prognostic value of Y deletion analysis. The role of current methods.

Abstract

Y chromosome microdeletions represent the most frequent genetic alteration in azoospermic and severely oligozoospermic men, and screening for microdeletions in AZFa, b and c are routinely performed in the major andrology and infertility centres. Since patients with Y microdeletions often require intracytoplasmic sperm injection (ICSI), the question of whether the type of the microdeletion present could have prognostic value for the presence of spermatozoa in the ejaculate or in the testes [by testicular sperm extraction (TESE)] is an interesting one. The review of the literature on this topic showed that there is still no clear genotype--phenotype relationship, i.e. similar testicular alterations may be caused by different types of microdeletions, and apparently identical microdeletions may be associated with diverse tubular damage. Even in azoospermic men, the localization of the microdeletion cannot be used as a valid prognostic parameter before TESE--ICSI to identify patients with spermatozoa in their testes. The only finding with absolute negative prognostic value is the presence of complete AZFa--c deletions, which are invariably associated with an absence of spermatozoa. Microdeletions in AZFa or AZFb seem to have promising prognostic value, but more data and gene-specific deletions have to be provided to draw clear conclusions. The absence of a clear genotype--phenotype relationship, and therefore of a prognostic value of Y deletion analysis, is probably due to the current methods used for the screening of the microdeletions. In fact, to date most centres do not use gene-specific markers but instead use anonymous primers that contribute little information to the pathogenic role of the microdeletions.