Background: Congenital thrombotic thrombocytopenic purpura ( cTTP ) is a rare autosomal recessive thrombotic microangiopathy caused by biallelic mutations in ADAMTS13 , leading to severe enzyme deficiency. The absence of ADAMTS13 prevents cleavage of ultra‐large von Willebrand factor multimers, resulting in platelet‐rich microthrombi formation. Pregnancy is a known precipitation factor, and early diagnosis and plasma treatment regimen to increase the ADAMTS13 activity is essential to prevent maternal and fetal complications. Case Report: We report the case of asymptomatic cTTP presenting in the third trimester of a first pregnancy. ADAMTS13 activity was <5%, and mixing studies excluded the presence of an inhibitor. Subsequent genetic testing revealed two pathogenic ADAMTS13 variants, including a previously unreported mutation, confirming the diagnosis of cTTP . The patient was treated with virus‐inactivated fresh frozen plasma during pregnancy and later with prophylactic infusions during the postpartum period. No clinical relapses occurred during follow‐up. Conclusion: This case highlights the diagnostic challenges of cTTP during pregnancy and emphasizes the importance of early ADAMTS13 activity testing, including inhibitor analysis. Although several international guidelines address cTTP management, individualized pregnancy and postpartum strategies remain essential. Our case supports the role of plasma prophylaxis and genetic confirmation in guiding long‐term management plans for affected individuals.

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms (MPNs), often associated with mutations in JAK2 , CALR , and MPL . Differentiating PV from ET can be challenging in borderline cases, particularly when hemoglobin (Hb), hematocrit (Hct) and erythropoietin (EPO) values are inconclusive. Functional iron parameters and JAK2 variant allele frequency (VAF) may provide additional discriminatory value. To assess the diagnostic utility of transferrin saturation index (TSI), serum ferritin, EPO, and JAK2 VAF in distinguishing PV from ET, and to evaluate their association with mutational profiles. We conducted a retrospective, single-center study including 260 adult patients diagnosed with PV or ET between 2009 and 2024. Demographic, clinical, molecular, and laboratory parameters—including ferritin, TSI, EPO, Hb, Hct, and JAK2 VAF—were analyzed. Comparative and correlation analyses were performed using appropriate statistical tests. Compared to ET, patients with PV had significantly lower ferritin (median: 35.65 vs. 95.05 ng/mL), TSI (12.9% vs. 21.64%), and EPO (2.23 vs. 6.11 mIU/mL), but higher Hb (17.7 vs. 14.3 g/dL) and Hct (54.6% vs. 43.0%) (all p < 0.001). TSI discriminated PV from ET better than ferritin (p < 0.001 vs. p = 0.128). Among JAK2-mutated cases, VAF was higher in PV than ET (median: 48% vs. 21%, p = 0.003). VAF correlated inversely with ferritin, TSI, and EPO, and positively with Hct. TSI and JAK2 VAF outperform ferritin as diagnostic markers to differentiate PV from ET. Integrating functional iron parameters with molecular data improves diagnostic accuracy, particularly in clinically ambiguous cases, and supports their inclusion in MPN diagnostic algorithms.