A familial study of twins with severe asthenozoospermia identified a homozygous SPAG17 mutation by whole-exome sequencing.

Asthenozoospermia (AZS) is a common cause of male infertility, characterized by abnormal reduction in the motility of ejaculated spermatozoa. Here, in a patient from a consanguineous family, we identified a homozygous mutation (c.G4343A, p.R1448Q) in SPAG17 by whole-exome sequencing. The encoded protein, SPAG17, localizes to the axonemal central apparatus and is considered essential for flagellar waveform. In silico analysis revealed that R1448Q is a potential pathogenic mutation. Immunostaining and western blot assays showed that the R1448Q mutation may exert a negative effect on the steady-state of the SPAG17 protein. Therefore, SPAG17 may be a new pathogenic gene causing AZS.

TSGA10 is a novel candidate gene associated with acephalic spermatozoa.

Acephalic spermatozoa is a rare teratozoospermia associated with male infertility. However, the pathogenesis of this disorder remains unclear. Here, we report a 27 years old infertile male from a consanguineous family, who presented with 99% headless sperm in his ejaculate. Electron microscopic and immunofluorescence analysis suggested breakage at the midpiece of the patient's sperm cells. Subsequent whole-exome sequencing analysis identified a homozygous deletion within TSGA10 (c.211delG; p.A71Hfs*12), which resulted in the production of truncated TSGA10 protein. TSGA10 is a testis-specific protein that localized to the midpiece in the spermatozoa of a normal control; however, immunostaining failed to detect TSGA10 protein in the patient's sperm. Western blot analysis also showed complete absence of TSGA10 protein in the patient. One cycle of in vitro fertilization-assisted reproduction was conducted, but pregnancy was not achieved after embryo transfer, possibly due to poor embryo quality. Therefore, we speculate that the presence of rare sequence variants within TSGA10 may be associated with acephalic spermatozoa in humans.

DNAH6 is a novel candidate gene associated with sperm head anomaly.

Globozoospermia and acephalic spermatozoa are two rare sperm head anomalies associated with male infertility. Combination of the two phenotypes in the same patient is extremely rare, so the underlying pathogenesis of this disorder remains unclear. Here, we report a 35-year-old infertile male, who presented with 30% of sperm-lacked heads and 69% of sperm round-headed or small-headed with neck thickening in his ejaculate. Subsequent whole-exome sequencing (WES) analysis identified compound heterozygous variants within the DNAH6 gene. DNAH6 is a testis-specific-expressed protein that was localised to the neck region in the spermatozoa of normal control; however, immunofluorescent staining failed to detect DNAH6 protein in the patient's spermatozoa. Quantitative real-time PCR analysis also showed the complete absence of DNAH6 mRNA in the patient's spermatozoa. Moreover, two cycles of in vitro fertilisation (IVF)-assisted reproduction were carried out, but pregnancy was not achieved after embryo transfer. Therefore, rare sequence variants in DNAH6 might be susceptibility risks for human sperm head anomaly.

Headless spermatozoa in infertile men.

Spermatozoa morphology, an important parameter in a semen specimen's potential fertility evaluation, is a significant factor for in vitro fertilisation in assisted reproductive technology. Eleven sterile men with headless spermatozoa, a type of human teratozoospermia, are presented. Their ejaculates' headless spermatozoa percentages were high with rare normal spermatozoa forms. Additionally, abnormal morphology (e.g. round-headed or microcephalic spermatozoa) was also found. Spermatozoa motility was somewhat affected, potentially because of the missing mitochondrial sheath at the sperm tail base. Patients who underwent assisted reproductive technology treatment experienced adverse pregnancy outcomes. Work types and corresponding environments seemed irrelevant, but specific family history may have prompted its genetic origin. Computer-assisted semen analysis systems easily mistake headless spermatozoa as oligozoospermia because of nonrecognition of the loose head. However, morphological testing, especially with an electronic microscope, clearly identifies abnormal spermatozoa. Future exploration requires more methods investigating the frequency and percentage of this morphological abnormality in different populations with varied fertility levels. Such research would estimate the probable correlation of the abnormality with other semen parameters and examine the potential developmental or genetic origins. During clinical work, medical staff should detect these cases, avoid misdiagnosis and provide proper consultation about diagnosis and assisted reproductive technology treatment.

Cleavage of DNA by N-phosphoryl histidine.

DNA cleavage by N-(O,O-diisopropyl)phosphoryl histidine(DIPP-His) is investigated by a submarine agarose electrophoresis technique. It was found that DIPP-His could cleave supercoiled DNAs and lambda DNA without the participation of divalent metal ions, while the histidine itself and N-(O,O-diisopropyl)phosphoryl alanine had no such function. Supercoiled pUC8 and pBR322 DNAs are cleaved to linear DNA and eventually fragments; lambda DNA is cleaved directly to fragments. Two mechanistic pathways are proposed for the cleavage reaction.