Polymerase chain reaction screening for Y chromosome microdeletions: a first step towards the diagnosis of genetically-determined spermatogenic failure in men.

Overall, approximately 11% of men attending infertility clinics suffer unexplained oligo- or azoospermia. Cytogenetic observations of loss of the distal portion of the Y chromosome long arm (Yq) were found to be associated with disrupted spermatogenesis. The existence of a gene locus involved in the regulation of spermatogenesis, the azoospermia factor (AZF), was thus postulated. It is suggested that microdeletions, or mutations, at the AZF locus could result in impaired spermatogenesis in chromosomally normal men. In order to test this hypothesis we have carried out Y chromosome genetic screening of 100 oligo- or azoospermic 46XY patients. We have also assessed phenotype/genotype relationships in those patients whose infertility has an underlying genetic aetiology. Patients were screened by polymerase chain reaction (PCR) with a set of Y chromosome-specific sequence tagged sites (STS) for submicroscopic deletions of their Y chromosome. Our results show that as many as 8% of cases of unexplained male infertility may have an underlying genetic aetiology related to microdeletions in two specific regions of the Y chromosome. Positive results from such a screen will be important when deciding the suitability of a patient for assisted conception schemes such as intracytoplasmic sperm injection.