Molecular reversion field
From Memory Alpha, the free Star Trek reference.
A molecular reversion field is a spatial anomaly that can interfere with transporter patterns and the molecular structures of objects passing through it.
In 2369, the shuttlecraft Fermi was trapped in and destroyed by such a field. Traveling aboard the shuttle were Captain Jean-Luc Picard, Ensign Ro Laren, Keiko O'Brien, and Guinan. As the shuttle began to break up, the USS Enterprise-D attempted to beam them off the shuttle. The molecular reversion field obscured portions of their patterns, in particular the ribo-viroxic-nucleic structure of their DNA, and the transporter re-materialized all four without it. (TNG: "Rascals")
