An Active Isodicentric X Chromosome in a Case of Refractory Anaemia with Ring Sideroblasts Associated with Marked Thrombocytosis

Abstract EN

Refractory anaemia with ring sideroblasts and marked thrombocytosis (RARS-T) is a provisional entity in the World Health Organization (WHO) classification.

It displays features characteristic of both myelodysplastic syndrome and myeloproliferative neoplasia plus ring sideroblasts ≥15% and marked thrombocytosis.

Most patients with RARS-T show a normal karyotype.

We report a 76-year-old woman diagnosed with RARS-T (76% of ring sideroblasts) with JAK2 (V617F) mutation and a load of 30–40%.

Classical and molecular cytogenetic (FISH) studies of a bone marrow sample revealed the presence of isodicentric X chromosome [(idic(X)(q13)].

Moreover, HUMARA assay showed the idic(X)(q13) as the active X chromosome.

This finding was correlated with the cytochemical finding of ring sideroblasts.

To our knowledge, this is the first reported case of an active isodicentric X in a woman with RARS-T.