Bi-allelic Mutations in TTC29 Cause Male Subfertility With Asthenoteratospermia in Humans and Mice

Am J Hum Genet. 2019 Dec 5;105(6):1168-1181. doi: 10.1016/j.ajhg.2019.10.010. Epub 2019 Nov 14.

Abstract

As a type of severe asthenoteratospermia, multiple morphological abnormalities of the flagella (MMAF) are characterized by the presence of immotile spermatozoa with severe flagellar malformations. MMAF is a genetically heterogeneous disorder, and the known MMAF-associated genes can only account for approximately 60% of human MMAF cases. Here we conducted whole-exome sequencing and identified bi-allelic truncating mutations of the TTC29 (tetratricopeptide repeat domain 29) gene in three (3.8%) unrelated cases from a cohort of 80 MMAF-affected Han Chinese men. TTC29 is preferentially expressed in the testis, and TTC29 protein contains the tetratricopeptide repeat domains that play an important role in cilia- and flagella-associated functions. All of the men harboring TTC29 mutations presented a typical MMAF phenotype and dramatic disorganization in axonemal and/or other peri-axonemal structures. Immunofluorescence assays of spermatozoa from men harboring TTC29 mutations showed deficiency of TTC29 and remarkably reduced staining of intraflagellar-transport-complex-B-associated proteins (TTC30A and IFT52). We also generated a Ttc29-mutated mouse model through the use of CRISPR-Cas9 technology. Remarkably, Ttc29-mutated male mice also presented reduced sperm motility, abnormal flagellar ultrastructure, and male subfertility. Furthermore, intracytoplasmic sperm injections performed for Ttc29-mutated mice and men harboring TTC29 mutations consistently acquired satisfactory outcomes. Collectively, our experimental observations in humans and mice suggest that bi-allelic mutations in TTC29, as an important genetic pathogeny, can induce MMAF-related asthenoteratospermia. Our study also provided effective guidance for clinical diagnosis and assisted reproduction treatments.

Keywords: CRISPR; MMAF; TTC29; WES; asthenoteratospermia; intraflagellar transport; male subfertility; mouse model; sequencing; sperm flagella.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Biomarkers, Tumor
  • Case-Control Studies
  • Combined Modality Therapy
  • Female
  • Follow-Up Studies
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Lymphatic Metastasis
  • Male
  • Mice
  • Middle Aged
  • Neoplasm Invasiveness
  • Neoplasm Recurrence, Local / drug therapy
  • Neoplasm Recurrence, Local / pathology
  • Neoplasms / drug therapy*
  • Neoplasms / pathology
  • Prognosis
  • Retrospective Studies
  • Survival Rate

Substances

  • Biomarkers, Tumor