Fig. 1

Identification of a homozygous frameshift deletion variant in PIWIL2 gene in a man with complete SCOS. A The patient (IV 1) came from a consanguineous family where his father (III 1) and mother were first-cousins, and his siblings were fertile. B Sanger sequencing confirmed the homozygous c.731_732delAT variant in PIWIL2 in the patient and the same variant in heterozygosis in his father and brother (IV 2). C The homozygous c.731_732delAT variant located in exon 6 of PIWIL2. This variant introduced a premature stop codon that resulted in a truncated PIWIL2 protein (273 aa), which lacked functional domains of PIWIL2 protein. D H&E-stained testicular sections of the patient showed no spermatogenic cells existed in seminiferous tubules and only Sertoli cells arranged on the membrane in all observed seminiferous tubules. E Immunohistochemical detection of PIWIL2 with an antibody whose antigen was the middle part of PIWIL2 in testicular sections of the patient and man with normal spermatogenesis. No positive signal was observed in testicular tissue of the patient (Left and Right). PIWIL2 is expressed in spermatogonium, spermatocytes, and spermatids in testicular tissue of man with normal spermatogenesis (Positive control)