RESUMEN
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.