title: CODEC V1 WGS of sperm sample by ddBTP blocked end-repair
design: 20ng sperm DNA was prepared using CODEC adapter V1.  We modified ddBTP-blocked ER/AT [22] to start with fragmentation with HpyCH4V (NEB, R0620S) and AluI (NEB, R0137S) (Extended Data Figure 6b) in NEB CutSmart buffer at 37ºC for 15 min, purified with 2.5x AMPure XP beads. Fragmented DNA was A-tailed in NEBuffer 4 with Klenow fragment and dATP/ddBTP (ddTTP, ddCTP and ddGTP) at 37 °C for 30 min. Index used: ACCTATAGGTGCAACGAA,ACTAACTTCCATTGCACT