Test Details: Calreticulin (CALR) gene encodes a protein called calreticulin which is associated with protein folding, calcium level maintenance in cells and many other cell functions. Mutations in CALR causes excessive production of blood cells, leading to disorder known as Myeloproliferative Neoplasms (MPNs). The CALR mutation test helps diagnose and classify bone marrow disorders such as Essential thrombocythemia (ET), Polycythemia vera (PV) and Primary Myelofibrosis (PMF).