Successful sperm retrieval by microdissection testicular sperm extraction in a man with partial AZFb deletion: a case report

Introduction

Microdeletions of the Y chromosome can cause spermatogenesis defects (1), often resulting in azoospermia. The azoospermic factor (AZF) region on the long arm of the Y chromosome consists of three regions: AZFa, AZFb, and AZFc, and the amplicon region has a palindrome arrangement. The AZFc region is the most frequently deleted, followed by the AZFb+c region (2). Clinical findings will differ depending on the deleted AZF region. Because complete deletion of AZFb results in maturation arrest and no spermatogenesis, testicular sperm extraction (TESE) is not usually advised in such cases. However, there are very few reports on spermatogenesis in partial deletions of the AZFb region (3,4). This study reports a case of partial deletion of the AZFb region in which sperm cells were successfully retrieved by microdissection TESE (micro-TESE). We present this article in accordance with the CARE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-24-426/rc).

Case presentation

A 34-year-old man (height 166 cm, weight 68 kg) with no medical history or history of infertility was referred to Reproduction Center, Yokohama City University Medical Center. Semen analysis performed at previous hospital revealed cryptozoospermia, with only one motile sperm with normal morphology identified in the pellet of the ejaculate after centrifugation. Physical examination revealed a testicular volume of 20 mL bilaterally. No varicocele was found, and the vas deferens and epididymis were normal. Endocrinological findings showed that serum levels of luteinizing hormone (5.4 mIU/mL), follicle-stimulating hormone (5.0 mIU/mL), total testosterone (234 ng/dL), estradiol (<25.0 pg/mL), and prolactin (4.8 ng/mL) were all within normal ranges, except for a mildly low testosterone level. Chromosome examination revealed a normal karyotype (46,XY) but loss of amplification of sY1024, the sequence-tagged site (STS) marker of the proximal portion of the AZFb region, in the Y chromosome palindrome region, as shown in the AZF microdeletion tests (GENOSEARCH™ AZF deletion kit) (5) (Figure 1). Partial deletion of AZFb was considered responsible for the spermatogenesis disorder. We recommended genetic counseling for the couple, but they declined. Micro-TESE was deemed to be indicated, as only one spermatozoon was observed in the pellet of the ejaculate after centrifugation. Thus, we therefore performed micro-TESE on the left testis.

Figure 1 AZF region of Y chromosome including sY1024 deletion of AZFb. Yp, short arm of Y chromosome; Yq, long arm of Y chromosome.

Gross findings of the seminiferous tubules revealed uniform thickness (Figure 2). We sampled the expanded seminiferous tubules and handed them to the embryologists. The collected testicular tissue was minced, and an embryologist examined the suspension intraoperatively. Several immotile spermatozoa were identified, all of which were malformed (Figure 3). Ninety-seven spermatozoa were observed per milliliter of testicular tissue suspension in the laboratory, all of which were malformed and immotile. The tissue suspension was washed with culture medium, and the cell components were frozen in liquid nitrogen. Histopathological findings on testicular biopsy showed germ cell differentiation and some spermatocytes and spermatozoa in the seminiferous tubules. Johnsen’s score ranged from 4 to 8 (Figure 4).

Figure 2 Intraoperative finding of seminiferous tubules. The thickness of the seminiferous tubules is uniform throughout.

Figure 3 Malformed sperm with irregular heads were observed (non-staining, ×400, scale bar: 20 µm).

Figure 4 Histopathological findings of the seminiferous tubules. (A) Multiple stages of germ cells, from immature cells to mature sperm, are observed (HE staining, ×200; Johnsen’s score 8). (B) Immature germ cells are observed (HE staining, ×200; Johnsen’s score 4). HE, hematoxylin and eosin.

Subsequently, intracytoplasmic sperm injection (ICSI) was performed using frozen-thawed testicular sperm that showed slight mobility, but the embryos rarely reached the good blastocyst stage. Despite two frozen-thawed embryo transfers, his wife has not achieved pregnancy.

All procedures performed in this study were in accordance with the ethical standards of the institutional review board of Yokohama City University Medical Center and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Y chromosome microdeletions are common causes of spermatogenesis defects (1), occurring in 7–23% of patients with nonobstructive azoospermia and in 1–8% of patients with severe oligozoospermia (6-9). In a survey of 1,030 Japanese patients with azoospermia and severe oligozoospermia, AZFc deletion was the most common cause of same (5.0%), followed by AZFb+c deletion (1.0%), and AZFa/AZFb deletion (0.4% each) (2).

The likelihood of identifying mature spermatozoa depends on the type of Y chromosome microdeletion. Spermatogenesis is not expected with complete AZFa, AZFb, or AZFb+c deletion, which is not an indication for TESE. The chance of recovering testicular spermatozoa in men with azoospermia and AZFc deletion is 50–60% (10). However, there are few reports of mature spermatozoa being detected in men with AZFb deletion (4).

There are different subtypes of AZFb deletion. Complete AZFb deletion is associated with germ cell maturation arrest through meiosis into spermiogenesis, whereas partial AZFb deletion is associated with various semen findings, including azoospermia and oligozoospermia (4,11). There has also been a report of childbirth through ICSI using sperm from patients with severe oligoasthenoteratozoospermia who have partial AZFb deletions (3). In this case, a few spermatozoa were observed in the ejaculate, and the spermatozoa could be retrieved by micro-TESE.

The degree of deletion of the AZFb region correlates with testicular histological findings, and spermatogenesis defects in testicular tissue are frequently observed in partial AZFb deletions, whereas more severe findings have been observed in complete AZFb deletions (4). Therefore, Krausz et al. reported that the exact extent and location of the AZFb deletion must be evaluated to determine whether the deletion in the AZFb region is a partial or complete deletion, as well as to obtain mature spermatozoa (12).

It has been suggested that an undamaged proximal region of AZFb leads to spermatogenesis (13). This region contains sperm-specific genes and is preserved in approximately half of partial AZFb deletions, and it has been reported that both distal and proximal AZFb deletions have spermatozoa in the testis or semen (4). Although the American Society for Reproductive Medicine and American Urological Association guidelines (14) and European Association of Urology guidelines (15) do not necessarily recommend a specific AZF deletion assay kit, they do state that a kit with STS probes detecting a larger number of microregions should be used. Using a limited set of primers may result in missing small deletions. In this case, the proximal region of AZFb (STS marker of sY1024) had a partial deletion, and a small number of spermatozoa were found in the ejaculated semen, suggesting that spermatogenesis was preserved and that spermatozoa could be retrieved via micro-TESE. However, because spermatozoa with normal morphology could not be identified in the testicular tissue, this region is speculated to be involved in the normal differentiation of sperm head morphology. In such cases, methods like in vitro fertilization and increasing the maturity of testicular sperm are considered to improve the fertilization rate. In this case, the low fertilization and blastocyst rates, along with the failure to achieve pregnancy, suggest that critical functions associated with embryonic development may be affected by the specific part of the deletion. Further studies on the role of each AZFb region are needed.

Conclusions

We report a case in which mature spermatozoa were obtained by micro-TESE in an azoospermic patient with partial deletion of AZFb. In the case of partial deletion of AZFb, micro-TESE should also be considered in cases of azoospermia as spermatogenesis may be preserved.

Acknowledgments

We thank Dr. Shinnosuke Kuroda for his advice on the details of genetic testing and Dr. Takuma Arai for pathological diagnosis. We also thank Enago (https://www.enago.jp) for editing the draft of this manuscript.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-24-426/rc

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-24-426/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-24-426/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work, ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional review board of Yokohama City University Medical Center and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Kuroda S, Usui K, Sanjo H, et al. Genetic disorders and male infertility. Reprod Med Biol 2020;19:314-22. [Crossref] [PubMed]
2. Iijima M, Shigehara K, Igarashi H, et al. Y chromosome microdeletion screening using a new molecular diagnostic method in 1030 Japanese males with infertility. Asian J Androl 2020;22:368-71. [Crossref] [PubMed]
3. Shi YC, Cui YX, Zhou YC, et al. A rare Y chromosome constitutional rearrangement: a partial AZFb deletion and duplication within chromosome Yp in an infertile man with severe oligoasthenoteratozoospermia. Int J Androl 2011;34:461-9. [Crossref] [PubMed]
4. Kleiman SE, Yogev L, Lehavi O, et al. The likelihood of finding mature sperm cells in men with AZFb or AZFb-c deletions: six new cases and a review of the literature (1994-2010). Fertil Steril 2011;95:2005-12, 2012.e1-4.
5. Iijima M, Koh E, Izumi K, et al. New molecular diagnostic kit to assess Y-chromosome deletions in the Japanese population. Int J Urol 2014;21:910-6. [Crossref] [PubMed]
6. Pryor JL, Kent-First M, Muallem A, et al. Microdeletions in the Y chromosome of infertile men. N Engl J Med 1997;336:534-9. [Crossref] [PubMed]
7. Kleiman SE, Yogev L, Gamzu R, et al. Genetic evaluation of infertile men. Hum Reprod 1999;14:33-8. [Crossref] [PubMed]
8. Peterlin B, Kunej T, Sinkovec J, et al. Screening for Y chromosome microdeletions in 226 Slovenian subfertile men. Hum Reprod 2002;17:17-24. [Crossref] [PubMed]
9. Girardi SK, Mielnik A, Schlegel PN. Submicroscopic deletions in the Y chromosome of infertile men. Hum Reprod 1997;12:1635-41. [Crossref] [PubMed]
10. Shah R, Gupta C. Advances in sperm retrieval techniques in azoospermic men: A systematic review. Arab J Urol 2017;16:125-31. [Crossref] [PubMed]
11. Fedder J, Fagerberg C, Jørgensen MW, et al. Complete or partial loss of the Y chromosome in an unselected cohort of 865 non-vasectomized, azoospermic men. Basic Clin Androl 2023;33:37. [Crossref] [PubMed]
12. Krausz C, Quintana-Murci L, McElreavey K. Prognostic value of Y deletion analysis: what is the clinical prognostic value of Y chromosome microdeletion analysis? Hum Reprod 2000;15:1431-4. [Crossref] [PubMed]
13. Costa P, Gonçalves R, Ferrás C, et al. Identification of new breakpoints in AZFb and AZFc. Mol Hum Reprod 2008;14:251-8. [Crossref] [PubMed]
14. Schlegel PN, Sigman M, Collura B, et al. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline Part I. J Urol 2021;205:36-43. [Crossref] [PubMed]
15. Minhas S, Bettocchi C, Boeri L, et al. European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2021 Update on Male Infertility. Eur Urol 2021;80:603-20. [Crossref] [PubMed]