Meanwhile, we found that compared with normal testicular tissues, IGF2BP1 was expressed at a lower level in testicular tissues of 3 types of NOA, including idiopathic NOA (iNOA), Klinefelter syndrome (KS), and AZFa-deletion (AZFa-del) (Fig. S2D and E), as well as in maturation arrest at spermatogonia (spg MA) (Fig. S2F and G), maturation arrest at spermatocytes (Spc MA) (Fig. S2F and G), and SCOS (Fig. S2F and G). Here, IGF2BP1 is linked to Klinefelter syndrome.