Molecular Human Reproduction vol.3 no.8 pp. 699–704, 1997 Combined cytogenetic and Y chromosome microdeletion screening in males undergoing intracytoplasmic sperm injection

4To whom correspondence should be addressed We evaluated the frequency of chromosomal aberrations and microdeletions of the Y chromosome in a sample of 204 patients included in an intracytoplasmic sperm injection (ICSI) programme. The prevalence of Y chromosome deletions in males with severely or only moderately reduced sperm 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 microdeletion of Yq11. One had a terminal deletion in subinterval 6 of Yq11.23 which included the DAZ gene and a corresponding sperm count,0.13106 spermatozoa/ml. The second patient had an isolated deletion of marker Y6PH54c, a more proximal site in subinterval 5 on Yq11.23, but repeatedly showed sperm counts of 3–83106 spermatozoa/ml. Thus, of the 158 patients who underwent a combined cytogenetic and Y-microdeletion screening, eight patients (5.1%) showed chromosomal abnorm-alities, either at the cytogenetic (n 5 6) or the molecular level (n 5 2). In conclusion, although rare in number, microdeletions of the Y chromosome can also be observed in patients with moderately reduced sperm counts. A more proximal site of the deletion breakpoint does not necessarily imply a more severe impairment of spermatogenesis than a distal deletion site. In our sample, the overall frequency of constitutional chromosomal aberrations exceeded the incidence of microdeletions of the Y chromosome even in patients with idiopathic azoo- or severe oligozoospermia. Key words: azoospermia/constitutional chromosome aberrations/genetic risk/oligozoospermia/Y chromosome microdeletion