Transferrin isoelectric focusing (TIEF). Abnormal TIEF, showing decreased tetrasialo transferrin with elevated disialotransferrin isoforms in the patient (lane 8). Lane 1, healthy control; lane 2, PGM1-CDG positive control; lanes 3-7, normal controls. Differences in specific TIEF bands of the patients are indicated with arrows. Arrows from top to bottom- 1. tetrasialotransferrin, 2. disialotransferrin, 3. asialotransferrin