Abstract
BackgroundNon-obstructive azoospermia (NOA) is the most severe form of male infertility; more than half of the NOA patients are idiopathic. Although many NOA risk genes have been detected, the genetic factors for NOA in majority of the patients are unknown. In addition, it is difficult to retrieve sperm from these patients despite using the microsurgical testicular sperm extraction (microTESE) method. Therefore, we conducted this genetic study to identify the potential genetic factors responsible for NOA and investigate the sperm retrieval rate of microTESE for genetically deficient NOA patients.MethodsSemen analyses, sex hormone testing, and testicular biopsy were performed to categorize the patients with NOA. The chromosome karyotypes and Y chromosome microdeletion analyses were used to exclude general genetic factors. Whole exome sequencing and Sanger sequencing were performed to identify potential genetic variants in 51 patients with NOA. Hematoxylin and eosin staining (H&E) and anti-phosphorylated H2AX were used to assess the histopathology of spermatogenesis. Quantitative real time-polymerase chain reaction, western blotting, and immunofluorescence were performed to verify the effects of gene variation on expression.ResultsWe performed whole exome sequencing in 51 NOA patients and identified homozygous helicase for meiosis 1(HFM1) variants (NM_001017975: c.3490C > T: p.Q1164X; c.3470G > A: p.C1157Y) in two patients (3.9%, 2/51). Histopathology of the testis showed that spermatogenesis was completely blocked at metaphase in these two patients carrying the HFM1 homozygous variants. In comparison with unaffected controls, we found a significant reduction in the levels of HFM1 mRNA and protein expression in the testicular tissues from these two patients. The patients were also subjected to microTESE treatment, but the sperms could not be retrieved.ConclusionsThis study identified novel homozygous variants of HFM1 that are responsible for spermatogenic failure and NOA, and microTESE did not aid in retrieving sperms from these patients.
Highlights
Azoospermia is a medical condition characterized by the absence of sperms in the ejaculated semen
We identified two novel homozygous variants of Helicase for meiosis 1 (HFM1) in two patients with Non-obstructive azoospermia (NOA), which strengthens the clinical significance of HFM1 for NOA phenotype
Homozygous variants in HFM1 were identified in two 1KGP Genomes Project (Chinese) men with NOA We performed bioinformatics analysis of the Whole exome sequencing (WES) data of one patient with NOA from a consanguineous family (F1 II-1) and found a homozygous HFM1 loss-of-function variant (NM_001017975: c.3490C > T: p.Q1164X), which was absent in our 500 in-house Chinese unrelated cohort controls in the general population
Summary
Azoospermia is a medical condition characterized by the absence of sperms in the ejaculated semen. Azoospermia is the most severe form of male infertility and accounts for approximately 1% of the total male population and 10% of the infertile males globally [1, 2]. It is a challenge to retrieve sperms from patients with NOA, even by microsurgical testicular sperm extraction (microTESE) [5, 6]. Non-obstructive azoospermia (NOA) is the most severe form of male infertility; more than half of the NOA patients are idiopathic. It is difficult to retrieve sperm from these patients despite using the microsurgical testicular sperm extraction (microTESE) method. We conducted this genetic study to identify the potential genetic factors responsible for NOA and investigate the sperm retrieval rate of microTESE for genetically deficient NOA patients
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