Expression pattern of germ cell–specific genes in the testis of patients with nonobstructive azoospermia: usefulness as a molecular marker to predict the presence of testicular sperm

Abstract

Objective: To analyze the expression pattern of testis-specific genes of patients with various spermatogenic defects and their usefulness as a molecular marker to predict the presence of testicular spermatozoa in patients with nonobstructive azoospermia undergoing IVF. Design: Prospective, controlled study. Setting: Hospital-based infertility research laboratory. Patient(s): Fifty-eight men with azoospermia or severe oligozoospermia. Intervention(s): Testicular biopsy was done in the patients with obstructive or nonobstructive azoospermia, including Sertoli cell–only syndrome, maturation arrest, severe hypospermatogenesis, and normal spermatogenesis. Main Outcome Measure(s): Reverse transcriptase polymerase chain reaction was performed using 1 μg of total RNA extracted from testicular tissues. Three pairs of primers were used for amplification of male germ cell–specific genes ( DAZ, transcribed in male germ cells; PGK2, in late spermatocytes and spermatids; protamine-2, in spermatids) as molecular markers. Testicular sperm was obtained by multiple testicular sperm extraction. Result(s): The DAZ, PGK2, and protamine-2 genes were expressed in 38, 30, and 21 of the 43 patients with nonobstructive azoospermia, respectively. Testicular spermatozoa were successfully extracted in 4 of 43 patients with nonobstructive azoospermia with the use of multiple testicular sperm extraction. Detection of protamine-2 transcripts predicted the presence or absence of spermatozoa in the testicular tissue in 39 of 43 patients (91%). Conclusion(s): Expression of the protamine-2 gene may be a useful molecular marker to predict the presence of testicular sperm in patients with nonobstructive azoospermia.