USB1 and pontocerebellar hypoplasia type 7: Functions of these enzymes are central to human health, with TOE1 mutations associated with Pontocerebellar Hypoplasia Type 7 (PCH7) (3), PARN mutations with Dyskeratosis Congenita and other human disorders (26, 27), PNLDC1 mutations with azoospermia (28), and USB1 mutations with Poikiloderma with neutropenia (29).