Fig 2: Pathogenic variants of ACTRT1 caused acephalic spermatozoa syndrome. (A) Morphological analysis of spermatozoa from patients with ACTRT1 mutations. Control subjects’ spermatozoa exhibited normal morphology, with the head and tail closely linked, while more than half of the patients’ spermatozoa were headless. (B) Immunofluorescence staining of ACTRT1 on the spermatozoa from control subjects and the patients.

Fig 3: Label-free quantitative proteomics analysis of the testes from Actrt1-null mice. (A) Gene ontology analysis of the changed proteins from the testis of Actrt1-knockout mice. (B) Western blot analysis the expression of the proteins associated with acephalic spermatozoa syndrome. (C) The quantitative results from three independent experiments as described in (B). *P < 0.05.

Fig 4: Identification of pathogenic variants in ACTRT1 from two patients with acephalic spermatozoa syndrome. (A) Pedigree chart of the two patients harboring ACTRT1 variants. The black squares represent the patients. (B) Sanger sequencing verified the pathogenic variants in the two patients. The mutation sites are indicated by the red rectangles. (C) Alignment analysis of the ACTRT1 amino acid sequences in different species in the affected sites, p.Arg32 and p.Tyr221.

Fig 5: Locations of the amino acids affected by pathogenic variants in the three-dimensional structure of ACTRT1. (A) The positions of the amino acid substitutions in the three-dimensional structure of the original ACTR1 protein. (B) The pathogenic variant c.95G>A:p.Arg32His effect on the three-dimensional structure of ACTRT1. (C) The pathogenic variant c.662A>G:p.Tyr221Cys effect on the three-dimensional structure of ACTRT1.