COMBINED CYTOGENETIC AND Y-CHROMOSOME MICRODELETION SCREENING IN MALES UNDERGOING INTRACYTOPLASMIC SPERM INJECTION

We evaluated the frequency of chromosomal aberrations and microdeletio ns of the Y chromosome in a sample of 204 patients included in an intr acytoplasmic sperm injection (ICSI) programme. The prevalence of Y chr omosome deletions in males with severely or only moderately reduced sp erm counts is mainly unknown, so that patients were chosen with sperm counts ranging from mild oligozoospermia to azoospermia. While six out of 158 (3.8%) patients showed constitutional chromosomal aberrations, only two out of 204 (0.98%) patients were diagnosed with a microdelet ion of Yq11. One had a terminal deletion in subinterval 6 of Yq11.23 w hich included the DAZ gene and a corresponding sperm count <0.1x10(6) spermatozoa/ml. The second patient had an isolated deletion of marker Y6PH54c, a more proximal site in subinterval 5 on Yq11.23, but repeate dly showed sperm counts of 3-8x10(6) spermatozoa/ml. Thus, of the 158 patients who underwent a combined cytogenetic and Y-microdeletion scre ening, eight patients (5.1%) showed chromosomal abnormalities, either at the cytogenetic in = 6) or the molecular level (n = 2). In conclusi on, although rare in number, microdeletions of the Y chromosome can al so be observed in patients with moderately reduced sperm counts. A mor e proximal site of the deletion breakpoint does not necessarily imply a more severe impairment of spermatogenesis than a distal deletion sit e. In our sample, the overall frequency of constitutional chromosomal aberrations exceeded the incidence of microdeletions of the Y chromoso me even in patients with idiopathic azoo- or severe oligozoospermia.