The overall prevalence of micro-deletions among nearly 5,000 infertile men, published in the literature, is 8% [7]. However, the incidence of Y micro-deletions in infertile men varies greatly between studies, from 1% [4] to 55% [5]. This variability can be explained by factors related to: 1) study design (inclusion criteria, clinical definition of patients); 2) lack of rigorous testing of nega­tive results (false deletions); and 3) ethnic and geographic differences of the studied populations. A recent review article comparing four different populations studied by a similar set of primers and using homogenous criteria for definition of idiopathic infertility, has shown that the main factor influencing deletion frequency is the composition of the study population, while ethnic or geographical differ­ences have no influence [14]. Micro-deletions were found almost exclusively in infertile men with azoospermia and severe oligozoospermia (sperm concentrations of <5 x 10⁶/mL). Deletions are extremely rare in men with a sperm concentration of >5 x 10⁶/mL [6,7].

Among the 109 infertile male patients studied we have detected a total of seven micro-deletions. Six of the patients with deletions were affected with azoospermia, while one was diagnosed as severely oligozoospermic. Thus, the overall frequency of Y chromosome micro-dele­tions among infertile males from the Republic of Macedo­nia is 6.4%. (16.7% among men with azoospermia, 2.8% among men with oligozoospermia <5 x 10⁶/mL, and 9.7% among men with a sperm count of <5 x 10⁶/mL). No dele­tion was identified among the infertile patients with oligo­asthenoteratozoospermia >5 x 10⁶/mL and normoastheno­teratozoospermia. These data are in agreement with those already published in the literature.

Among the seven patients with micro-deletions, de­tected in our study, six carried a deletion limited to the AZFc region, while one had a larger deletion involving two AZF regions (b and c). Our results, confirm that AZFc deletions are the most common Y micro-deletions.

Many authors have tried to make genotype-spermato­genic phenotype correlation in patients with Y micro-deletions. However, these studies have shown that similar or identical deletions can cause different impairments of spermatogenesis. In our study, five of the six patients with AZFc deletions presented with azoospermia and one with severe oligozoospermia. The testicular histology was available in three of the patients with AZFc deletions, and showed SCOS in two and hypospermatogenesis in one. Our results support the observation that the most common Y micro-deletions, the AZFc deletions, are associated with different seminal pattern and testicular histology.

Of the seven patients with micro-deletions, six demon­strated no etiological cause of infertility, whereas in one a varicocele was present. Thus, our study confirmed the previous observations that Y deletions are present in pa­tients with non idiopathic infertility [15-17]. This supports the relevance of micro-deletion screening in patients with evident cause of infertility, such as a varicocele.