To identify novel variants in ACTL9 and new phenotypes responsible for male infertility.
Genomic DNA was extracted from peripheral blood samples for whole-exome sequencing (WES). Computer-assisted sperm analysis (CASA) was used to test the motility of spermatozoa. The ultrastructure of flagella and the mitochondrial sheath were assessed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Immunostaining was used to validate the localization and expression of ACTL9 and ACTL7A. An Actl9-mutated mouse model was used to validate the phenotypes by CASA and TEM.
We identified novel homozygous variants in ACTL9 in two independent Chinese families. Spermatozoa with ACTL9 mutations showed decreased CASA parameters and a higher proportion of spermatozoa with abnormal morphology, exhibiting coiled flagella and a thickened midpiece. The spermatozoa were characterized by chaotic or irregular '9+2' structures and irregular mitochondrial sheath arrangements in the flagellum. Actl9 knock-in mice also showed abnormal CASA parameters and irregular '9+2' structures in flagella.
Our study expands the mutation spectrum and phenotypic spectrum of ACTL9.
Journal of assisted reproduction and genetics. 2024 Jul 04 [Epub ahead of print]
Qi Li, Yilian Huang, Shen Zhang, Fei Gong, Guangxiu Lu, Ge Lin, Jing Dai
Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, 410008, China., Laboratory of Reproductive and Stem Cell Engineering, National Health and Family Planning Commission, Changsha, 410078, China., Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, 410008, China. .