ADAM9 and pachyonychia congenita: We deduced from the typical cases that a higher expression level of ANXA2 (cut-off threshold = 9.77), ADAM9 (cut-off threshold = 6.74), LAMC2 (cut-off threshold = 6.07), AGR2 (cut-off threshold = 9.68), MMP11 (cut-off threshold = 6.58), APLP2 (cut-off threshold = 8.31), and SERPINB5 (cut-off threshold = 4.46) was an indication of PC in this investigation.