Expression patterns and transcript concentrations of the autosomal DAZL gene in testes of azoospermic men

The DAZ (Deleted in AZoospermia) gene cluster on the Y chromosome is a stro ng candidate for the azoospermia factor. The DAZ gene was derived from an a utosomal homologue, DAZL (DAZ-Like). This study was designed to assess the functional role of DAZL in human spermatogenesis. The expression patterns a nd mRNA transcript levels of DAZL in the testes of 17 azoospermic men were therefore examined by immunohistochemical staining and quantitative competi tive reverse transcription-polymerase chain reaction. DAZL protein was expr essed in the cytoplasm of primary spermatocytes and weakly in spermatogonia . It was detected in the testicular tissues of all subjects with germ cells present. The copy number of the DAZL transcript in normal spermatogenesis (n = 4), hypospermatogenesis or maturation arrest (n = 6), and Sertoli cell -only syndrome (n = 7) ranged from 1.22 x 10(6) to 1.63 x 10(6) per ng of R NA, 1.19 x 10(5) to 2.82 x 10(5) per ng of RNA and 2.83 x 10(4) to 1.23 x 1 0(5) per ng of RNA respectively. DAZL transcripts were lower in men with sp ermatogenic failure, and a significant difference was found between the thr ee groups (P < 0.0001). This study suggests that DAZL may play an important role in the human spermatogenic processes of both mitosis and meiosis.