A novel homozygous mutation in DNAJB13-a gene associated with the sperm axoneme-leads to teratozoospermia

Purpose: To evaluate the unknown genetic causes of teratozoospermia, and determine the pathogenicity of candidate variants.

Methods: A primary infertile patient and his family members were recruited in the West China Second University Hospital of Sichuan University. Whole-exome sequencing was performed to identify causative genes in a man with teratozoospermia. Immunofluorescence staining and western blotting were applied to assess the pathogenicity of the identified variant. Intracytoplasmic sperm injection (ICSI) was used to assist fertilization for the patient with teratozoospermia.

Results: We performed whole-exome sequencing (WES) and detected a novel homozygous frameshift mutation of c.335_336del [p.E112Vfs*3] in DNAJB13 on a primary infertile male patient. Intriguingly, we identified abnormal sperm morphology in this patient, with recurrent respiratory infections and chronic cough. Furthermore, we confirmed that this mutation resulted in negative effects on DNAJB13 expression in the spermatozoa of the affected individual, causing ultrastructural defects in his sperm. Remarkably, our staining revealed that DNAJB13 was expressed in the cytoplasm of primary germ cells and in the flagella of spermatids during spermiogenesis in humans and mice. Finally, we are the first group to report a favorable prognosis using ICSI for a patient carrying this DNAJB13 mutation.

Conclusion: Our study revealed a novel homozygous frameshift mutation of c.335_336del [p.E112Vfs*3] in DNAJB13 involved in teratozoospermia phenotype. Our study greatly expands the spectrum of limited DNAJB13 mutations, and is expected to provide a better understanding of genetic counseling diagnoses and subsequent treatment of male infertility.