Identification of an SMC1B Mutation Associated With Necrozoospermia and Failure of Testi-ICSI : SMC1B Mutation Associated With Necrozoospermia.

Abstract

Investigating potential etiologies is important before selecting a therapeutic approach for male infertility. However, the genetic causes of idiopathic necrozoospermia are poorly understood. In this study, a heterozygous missense variant in SMC1B (NM_148674.5: c1856G > T; p.C619F) causing severe necrozoospermia in the infertile proband was identified by Whole-exome sequencing (WES). This phenotype was distinct from the phenotypes of other vertebrates harboring this mutation. Interestingly, Papanicolaou staining, light microscopy and electron microscopy results indicated severe abnormalities in the morphology of the sperm head and an irregular sperm ultrastructure in the patient with the identified variant. Additionally, the sharply decreased protein expression of SMC1B in spermatozoa and testicular tissues ultimately resulted in an abnormal chromatin structure and high sperm DNA fragmentation (SDF) in the male patient. Regrettably, poor outcomes of Intracytoplasmic sperm injection with testicular sperm (Testi-ICSI) treatment were observed for the patient harboring the identified SMC1B mutation. In Conclusion, a missense SMC1B mutation that may mediate impaired sperm vitality was the first time reported, providing new insights into a novel genetic etiology of necrozoospermia in humans.