Study On The Mechanism Of TSGA10 New Mutation Leading To Human Acephalic Spermatozoa

Acephalic spermatozoa is an extremely rare type of the teratozoospermia which associates with male infertility.According to the existing reports,only a few genes are considered to be related to the occurrence of human acephalic spermatozoa.Therefore,more genetic pathogenies need to be explored in order to provide the certain help for clinical diagnosis and subsequent treatment.Morphological analysis was performed on the semen of a recruited patient with acephalic spermatozoa,with other physical and chemical factors and other diseases that could cause acephalic spermatozoa performance excluded.Take the patient's peripheral blood for whole-exome sequencing,find the mutation site,and use the Sanger sequencing method to verify the gene mutation of the patient and his family.The protein expression of SUN5 gene and PMFBP gene in spermatozoa of the patient was detected to exclude the effects of other possible genes on the acephalic spermatozoa phenotype of the patient.Morphological analysis was performed on the sperm of the patient:the semen of the patient was observed under an optical microscope.No intact sperm was found in the semen,and most of them were headless sperm Observed under a transmission electron microscope,the patient's sperm's head was absent,what we can see is the tail structure,and the cytoplasmic droplets remained at the top of the tail.The number of mitochondria in the middle piece of the tail was reduced,the morphology and distribution were abnormal,and the mitochondrial sheaths were arranged disorderly,there was no central pairs and the peripheral double Microtubules,and the assembly of the outer dense fibers were incomplete.The cross-section of the principle piece was unclear.The "9+9+2" structure with axoneme surrounded by nine outer dense fibers was not found.The axoneme had obvious defects.This indicates that the cause of infertility in this patient is the headless sperm disordered mitochondrial sheath arrangement,and the flagellum abnormalities.Whole exome sequencing was performed on the patient's peripheral blood to identify the mutations in its related gene TSGA10.and further confirmed that the patient had a homozygous c.545dupT:p.Ala183Serfs*10 mutation by Sanger sequencing.Subsequently,the peripheral blood of his parents and sister was collected for Sanger sequencing.The results showed that his sister carried the wild-type alleles,and heterozygous c.545dupT:p.Ala 183Serfs*10 mutations were observed in Sanger sequencing of his father and mother,respectively.It was revealed that the frameshift insertion mutations carried by the patient were inherited from their parents.In addition,the amino acids encoded by this mutation sites are highly conserved among different species.Polyphen-2,SIFT,Mutation Taster,and SNPs&GO were then used for bioinformatics analysis,suggest that this new mutation had an impact on protein function.The frequency of this mutation observed in the general population was evaluated by using the ExAC and 1000 Genomes,and this mutation was considered to be a rare mutation.After imnunofluorescence detection,there was no obvious TSGA10 protein expression in the patient's sperm head and tail;however,the patient's sperm head still had SUN5 protein and PMFBP1 protein expression.Compared with the normal control group,there was no significant change in the protein expression level and location of the SUNS gene and PMFBP1 gene in this acephalic spermatozoa patient.Morphological analysis showed that the causes of infertility in this patient are headless sperm,disordered sperm mitochondrial sheath arrangement and flagella abnormality.Acephalic spermatozoa caused by TSGA10 gene mutation has an autosomal recessive inheritance pattern.The new homozygous frameshift insertion mutation c.545dupT:p.Ala 183Serfs*10 of TSGA10 gene may be the pathogenesis of acephalic spermatoza.