Frequency of Calreticulin (CALR) Mutation and Its Clinical Prognostic Significance in Essential Thrombocythemia and Primary Myelofibrosis: A Meta-analysis.

Objective As the calreticulin (CALR) mutation frequency is significantly associated with essential thrombocythemia (ET) and primary myelofibrosis (PMF), this mutation may be an important biomarker in patients with ET and PMF. Methods We performed a literature search until April 2015 and obtained 21 relevant studies. The outcome was pooled as the effect size by using the Stata software program. Results The CALR mutation frequencies in patients with ET and PMF were 19% and 22%, respectively. The CALR mutation ratio in Asian patients with ET was 23% and higher than that in European-American patients (16%). Moreover, the mutation ratio in Asian patients with PMF was lower (21%) than that in European-American patients (23%). A slight trend toward fibrotic transformation was found in ET with CALR mutations, whereas leukemic transformation was not significant in patients with ET or PMF with CALR mutations. Conclusion CALR mutations significantly influence the incident of ET as demonstrated by the meta-analysis.