[Identification and clinical implication of a novel variant of SPAG17 gene resulting in Familial severe asthenozoospermia].

Objective: To investigate the association between SPAG17 gene variant and Familial severe asthenozoospermia, and to assess its impact on the outcome of intracytoplasmic sperm injection (ICSI).

Methods: Two siblings (Probands 1 and 2) with severe asthenozoospermia from a Chinese family who presented at the Reproductive Medicine Center II of Gansu Maternity and Child Health Care Hospital (Gansu Provincial Central Hospital) in May 2023 were selected as study subjects. Clinical data were collected, and sperm morphology and ultrastructure (assessed by transmission electron microscopy) were analyzed. Pathogenic variants were screened using whole exome sequencing (WES) and verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of Gansu Maternity and Child Health Care Hospital (Ethics No.: 2023GSFYLS78).

Results: Probands 1 and 2 had primary infertility for 10 and 3 years, respectively, and both exhibited normal semen concentration, but the percentage of progressive motile sperm (PR) was significantly lower than the normal reference value (> 32.00%), measuring 2.33% ± 0.58% and 0.80% ± 0.45%, respectively. Additionally, the percentage of sperms with normal morphology was slightly below the reference range (> 4.00%), with the values of 3.36% ± 0.35% and 2.93% ± 1.36%. Both probands were found to harbor homozygous c.2188C>T (p.Q730*) nonsense variant of the SPAG17 gene (NM_206996.4), for which their mother was a heterozygous carrier (their father had already deceased). Both sibs underwent ICSI treatment using a long gonadotropin-releasing hormone agonist protocol during the follicular phase combined with assisted oocyte activation (AOA). The wife of Proband 1 ultimately gave birth to a healthy girl, whilst the wife of Proband 2 delivered two healthy girls.

Conclusion: The homozygous c.2188C>T (p.Q730*) nonsense variant of the SPAG17 gene is closely related with the severe asthenozoospermia phenotype. Live births can be achieved through ICSI combined with AOA technology, though the overall utilizable embryo rate may be relatively low.