Genetic variations of antioxidant genes and their association with male infertility in Vietnamese men.

BACKGROUND: Antioxidant genes, such as superoxide dismutase (SOD), catalase (CAT), and nitric oxide synthase (NOS), play critical roles in spermatogenesis and sperm functions. Polymorphisms of antioxidant genes have been shown to be strongly associated with sperm quality which affects male fertility. METHODS: To investigate the association of antioxidant gene polymorphisms to male infertility in Vietnamese men, in this case-control study, using Sanger sequencing, we genotyped four variants SOD1:7958G>A, SOD2:c.47T>C, CAT:-262C>T, and NOS3:-786C>T. RESULTS AND CONCLUSIONS: We identified SOD1:7958GA genotype and NOS3:-786CT genotype in the infertility group were significantly higher than in the control with OR = 2.191 (95% CI: 1.226-3.915, p = 0.004) and OR = 3.135 (95% CI: 1.591-6.180, p < 0.001), respectively. We also detected that the frequency of the SOD2:c.47TC genotype was significantly higher in the male infertility group than in fertile men (OR = 1.941, 95% CI: 1.063-3.595, p = 0.029). Gene-gene interactions between the SNPs of SOD1, SOD2, and CAT might increase the risk of male infertility patients. In particular, patients carrying the SOD1:GA+AA, SOD2:TC+CC, and CAT:CT/TT genotype pattern have an increased risk of male infertility (OR = 7.614, p = 0.007). To our knowledge, this is the first study to evaluate the association between the SOD1:7958G>A polymorphism and male infertility. Further studies with larger sample sizes and more genes are needed to better assess the association between variants of antioxidant genes and male infertility.

A Novel Frameshift Microdeletion of the TEX12 Gene Caused Infertility in Two Brothers with Nonobstructive Azoospermia.

Male infertility is a growing health problem, which affects approximately 7% of the global male population. Nonobstructive azoospermia (NOA) is one of the most severe forms of male infertility caused by genetic defects, including chromosome structural abnormalities, Y chromosome microdeletions, or single-gene alterations. However, the etiology of up to 40% of NOA cases is unidentified. By whole-exome sequencing, we detected a homozygous 5-bp-deletion variant in exon 4 of the TEX12 gene (c.196-200del, p.L66fs, NM_031275.4) in two brothers with NOA of a nonconsanguineous Vietnamese family. This deletion variant of 5 nucleotides (ATTAG) results in a premature stop codon in exon 4 and truncation of the C-terminal. Segregation analysis by Sanger sequencing confirmed that the deletion variant was inherited in an autosomal recessive pattern. The 1st and 3rd infertile sons were homozygous for the deletion, whereas the 2nd fertile son and both parents were heterozygous. The new deletion mutation identified in TEX12 gene caused loss of function of TEX12 gene. The loss of TEX12 function has already caused infertility in male mice. Therefore, we concluded that the loss of TEX12 function may cause infertility in men. To our knowledge, this is the first case reported so far indicating disruption of human TEX12, which leads to infertility in men.

Novel and very rare causative variants in the COL7A1 gene of Vietnamese patients with recessive dystrophic epidermolysis bullosa revealed by whole-exome sequencing.

BACKGROUND: Dystrophic epidermolysis bullosa (DEB) is a rare inherited disorder characterized by skin fragility leading to trauma-induced subepidermal blisters and healing with scarring. DEB is caused by mutations in COL7A1, the gene encoding for type VII collagen (COLVII). The DEB inheritance trait is divided into dominant dystrophic epidermolysis bullosa (DDEB) and recessive dystrophic epidermolysis bullosa (RDEB). METHODS: Whole-exome sequencing (WES) was performed for identifying mutations in six affected individuals of five Vietnamese families. RESULTS: Three novel variants in total of eight variants were found in five families. The first novel variant causing glycine substitution (c.8279G>A, p.G2760E), the remaining two novel variants resulted in splice site affecting (c.4518+2delT and c.5821-2A>G). Functional analysis indicated that the splice site at c.4518+2delT resulted in a skipping of exon 43, leading to an in-frame deletion of 12 amino acids. CONCLUSION: Our finding expands the spectrum of COL7A1 mutations and reports altered splicing at c.4518+2delT during the processing of the pre-mRNA. This study provides an additional scientific basis for diagnosis, genetic counseling, and prognosis purposes of EB patients.

Whole Genome Sequencing of a Vietnamese Family from a Dioxin Contamination Hotspot Reveals Novel Variants in the Son with Undiagnosed Intellectual Disability.

Although it has been a half-century since dioxin-contaminated herbicides were used to defoliate the landscape during the Vietnam War, dioxin contamination "hotspots" still remain in Vietnam. Environmental and health impacts of these hotspots need to be evaluated. Intellectual disability (ID) is one of the diseases found in the children of people exposed to the herbicides. This study aims to identify genetic alterations of a patient whose family lived in a dioxin hotspot. The patient's father had a highly elevated dioxin concentration. He was affected with undiagnosed moderate ID. To analyze de novo mutations and genetic variations, and to identify causal gene(s) for ID, we performed whole genome sequencing (WGS) of the proband and his parents. Two de novo missense mutations were detected, each one in ETS2 and ZNF408 genes, respectively. Compound heterozygosity was identified in CENPF and TTN genes. Existing knowledge on the genes and bioinformatics analyses suggest that EST2, ZNF408, and CENPF might be promising candidates for ID causative genes.