Screening for microdeletions on the long arm of chromosome Y in 53 infertile men.

About 30% of couple infertilities are of male origin. They appear in some cases de novo and are considered idiopathic. The aim of our work was to evaluate, in these cases, the prevalence of microdeletions of the long arm of chromosome Y, within the AZF a, b and c regions using molecular biology techniques. Men with azoospermia or oligozoospermia resulting from hereditary, endocrine or obstructive causes, or with a constitutional cytogenetic abnormality were excluded. Fifty-three infertile men with azoospermia or oligozoospermia, as determined by a spermiogram, were studied. Of these, 34 were idiopathic and 7 exhibited a past history of genital infection or biological abnormalities, suggesting partial obstruction of the genito-urinary tract. A further 8 men had a varicocele and 11 cases with a history of cryptorchidism were also studied. Peripheral blood DNA was extracted from each patient, then amplified by multiplex PCR with STS genomic markers from the three Y chromosome AZF zones. PCR products were then analysed on agarose gels. In view of the difficulty of confirming the absence of a signal in molecular biology, each case suspected of having a deletion was checked by multiplex PCR through coamplification with the SRY marker. Five men with microdeletions of the long arm of the Y chromosome were diagnosed among the 53 patients. All of them included the AZFc zone and the intragenic DAZ gene markers. Furthermore, a larger Y chromosome deletion encompassing the 3 AZF zones was diagnosed, and confirmed by cytogenetic analysis. All Y chromosome microdeletions were observed in the 34 truly idiopathic azoospermia/oligozoospermia cases, corresponding to a proportion of 14.7% (or 9.4% considering the whole population of 53 infertile men). The relatively high proportion of microdeletions found in our series suggests the need for strict patient selection to avoid unnecessary screening for long arm Y chromosome microdeletions.