ABSTRACT
Chromosomal abnormalities and Y chromosome microdeletions are considered to be the two more common genetic causes of spermatogenic failure. However, the relationship between chromosomal aberrations and Y chromosome microdeletions is still unclear. This study was to investigate the incidence and characteristics of chromosomal aberrations and Y chromosome microdeletions in infertile men, and to explore whether there was a correlation between the two genetic defects of spermatogenic failure. A 7-year retrospective study was conducted on 5465 infertile men with nonobstructive azoospermia or oligozoospermia. Karyotype analysis of peripheral blood lymphocytes was performed by standard G-banding techniques. Y chromosome microdeletions were screened by multiplex PCR amplification with six specific sequence-tagged site (STS) markers. Among the 5465 infertile men analyzed, 371 (6.8%) had Y chromosome microdeletions and the prevalence of microdeletions in azoospermia was 10.5% (259/2474) and in severe oligozoospermia was 6.3% (107/1705). A total of 4003 (73.2%) infertile men underwent karyotyping; 370 (9.2%) had chromosomal abnormalities and 222 (5.5%) had chromosomal polymorphisms. Karyotype analysis was performed on 272 (73.3%) patients with Y chromosome microdeletions and 77 (28.3%) had chromosomal aberrations, all of which involved sex chromosomes but not autosomes. There was a significant difference in the frequency of chromosomal abnormalities between men with and without Y chromosome microdeletions (P< 0.05).
ABSTRACT
Aim: Yq microdeletions involving the azoospermia factor (AZF) region are the second most frequent genetic cause of spermatogenic failure next to Klinefelter syndrome. These deletions occur in about 10-15 percent of men with azoospermia and severe oligozoospermia. Molecular screening for AZF deletions has become mandatory in the work-up of infertile men. Further, partial AZFc deletions categorized as gr/gr, b2/b3, b1/b3 and b2/b4 deletions have also been known to affect spermatogenesis. This study aimed to screen for both classical AZF deletions in 250 karyotypically normal infertile men from south India and partial AZFc deletions as a case-control analysis involving 108 fertile men. Methods: PCR amplification involving two multiplex reactions was carried out using primers for six STSs sY84, sY86 (AZFa), sY127, sY134 (AZFb), and sY254, sY255 (AZFc) with two internal controls (SRY, ZFY). Further, those men who showed deletions with one or both STSs sY1291 and sY1191 were subsequently tested with sY1189 and sY1192 to detect partial AZFc deletions. Results: One individual showed deletion of all the three AZF regions while two men had only AZFc deletion. Deletion of partial AZFb (sY127) was seen besides complete AZFc region in the fourth patient. The gr/gr, b2/b3 and b1/b3 deletions were detected in 24 (9.6%), one (0.4%) and nine (3.6%) infertile men in comparison with five, one and two fertile men respectively. The b2/b4 deletion was observed in a single azoospermic individual. Conclusion: Screening for AZF deletions would help in not only determining the cause for male infertility but also in its management and accurate genetic counselling.