Trisomy 3 is a consistent chromosome change in malignant lymphoproliferative disorders preceded by cold agglutinin disease.

Cold-antibody autoimmune haemolytic anaemia is a rare entity that has been associated with a wide variety of pathological processes, including malignant lymphoproliferative disorders. In this retrospective study we recorded, as far as possible, clinical, haematological, immunological, morphological, pathological, cytogenetic and molecular data on 10 patients with cold agglutinin disease (CAD). Cytogenetic anomalies were found in four cases in which an underlying lymphoma could be evidenced. Trisomy 3 was the only recurrent aberration in our series. It was observed in all patients with abnormal karyotype, either as a complete trisomy or as a partial trisomy of the long arm. The importance of this particular karyotypic aberration in the monitoring of CAD is emphasized.