Estimation by triple FISH of aneuploidy in testicular and epididymal spermatozoa of patients with obstructive and non obstructive azoospermia

Abstract

Epididymal or testicular spermatozoa, from patients with obstructive (OA) or non obstructive azoospermia (NOA), are currently use in ICSI. Many questions arise about the utilisation of immature spermatozoa taken from the genital male tract, particularly in terms of risk of chromosomal abnormality transmission to the newborn. Chromosomal equipment of epididymal and testicular spermatozoa from patients with OA or NOA were studied by Fluorescent In Situ Hybridization (FISH) Spermatozoa extracted from epididym of nine men with OA (unrelated to congenital bilateral absence of the vas deferens: CBAVD), and testicular spermatozoa of three men with NOA were studied by triple FISH X,Y,18. For four of the nine OA patients, triple FISH was performed also on testicular spermatozoa obtained during the same surgical attempt. Five ejaculated samples from normozoospermic men were used as control. Aneuploidy rates were compared between different groups by independent X2 test. A total of 33116 epididymal spermatozoa from the 9 OA patients, 1591 testicular spermatozoa for 4 OA patients, 1159 testicular spermatozoa for 3 NOA patients and 25000 ejaculated spermatozoa from control, were analysed. In OA epididymal spermatozoa autosomal disomy rate (0.19%) and gonosomal disomy rate (0.38%) were comparable to those observed in the control (0.22% and 0.32% respectively). OA testicular spermatozoa have higher aneuploidy rates, for chromosome 18 (0.53%) and gonosomes (1.05%), than in the control (p<0.05). The comparison between epididymal and testicular spermatozoa in the OA group shows higher autosomal aneuploidy rate in testicular spermatozoa (p<0.05). However, the aneuploidy rates were the highest in NOA testicular spermatozoa (2.09% for disomy 18 and 5.64% for gonosomal disomy) (p<0.0001). If epididymal spermatozoa of patients with OA have not a significantly higher aneuploidy rate than those in ejaculated spermatozoa, testicular spermatozoa of patients with NOA or OA, have a significantly higher aneuploidy rate than ejaculated and epididymal spermatozoa. The higher level of autosomal disomy in testicular as opposed to epididymal spermatozoa, in OA unrelated to CBAVD, of the same patients, concurs with the hypothesis of a selection mechanism for chromosomal abnormal spermatozoa, during the transfer from the testis toward the epididym. So it is important to study the chromosomal equipment of spermatozoa taken from the testis in order to determine the risk of using these spermatozoa in ICSI.