Similar results were reported in follow-up studies of 176 and 89 CALR mutated patients with ET [136,137], however, although no evidence of a higher transformation rate was found in these studies, Grinfeld et al. found an increased risk of transformation in their NGS study of 2035 MPN patients of whom 1321 had ET [20]. Here, CALR is linked to myeloproliferative disorder.