Mutations in PLCZ1 induce male infertility associated with polyspermy and fertilization failure

Purpose To investigate the genetic causes of polyspermy and total fertilization failure (TFF) in two independent male patients suffering from male infertility.Methods Immunofluorescence (IF) staining was used to detect the localization of the PLC zeta protein in sperm and the maternal pronucleus in the zygote. Genomic DNA samples were extracted from the peripheral blood of patients and their families. The ExAC database was used to identify the frequency of corresponding mutations. The PLCZ1 mutations were validated by Sanger sequencing. The pathogenicity of the identified mutations and their possible effects on the protein were assessed using in silico tools and molecular modeling.Results We identified a reported homozygous mutation c.588C > A (p.Cys196Ter) and a compound heterozygous mutation c.2 T > C(p.Met1Thr)/c.590G > A (p.Arg197His) with one novel mutation in PLCZ1. The IF results showed that these multipronuclear zygotes formed as a result of polyspermy. In silico analysis predicted that the mutations result in disease causing proteins. IF staining revealed that PLC zeta is abnormally localized in the sperm samples from the two affected patients. Assisted oocyte activation (AOA) successfully rescued polyspermy and TFF and achieved pregnancy in two patients with the PLCZ1 mutation.Conclusion We identified a homozygous mutation in PLCZ1 (c.588C > A [p.Cys196Ter]) in a male patient with polyspermy after in vitro fertilization (IVF) as well as a compound heterozygous mutation c.2 T > C(p.Met1Thr)/c.590G > A (p.Arg197His) with one novel mutation in a male patient with fertilization failure after intracytoplasmic sperm injection (ICSI), and we provide evidence that the homozygous mutation can cause polyspermy and the compound heterozygous mutation can cause fertilization failure.

Automated summary

This study investigates the genetic causes of polyspermy and total fertilization failure in two male patients with infertility. Homozygous and compound heterozygous mutations in the PLCZ1 gene were identified and shown to cause polyspermy and fertilization failure, respectively. Assisted oocyte activation was successfully used to treat these conditions.