A2M and Azoospermia: No significant differences in protein expression were revealed in the statistical comparisons between the three azoospermia groups (Supplementary Table 3), and several proteins showed similar fold changes in HC/OA and the HC/SCO comparisons, namely LDHC, A2M, DPEP3, HSPA2, HSPA4, and HSP90AA1 (Tables 1, 2).