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.

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 microgram 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.