Objective: To report characteristics and number of chromosome abnormalities detected in samples collected from patients
suspected of having haematological malignancy by clinicians.

Materials and Methods: We retrospectively reviewed karyotype data of 12,261 newly diagnosed haematological malignancy and follow-up cases who received conventional cytogenetic analyses at
Cancer Cytogenetics Unit, Chulabhorn Hospital between 2009 and 2015.

Results: Among the total suspected and follow-up haematological malignancy cases analysed, 35.22% (4,318 cases) had chromosomal aberrations while the other 64.78% (7,943 cases) showed normal
chromosome arrangements. Among the patients with chromosomal aberrations, there were 734 cases with numerical aberrations, another 2,621 cases with structural aberrations, and a further 963 cases reported with both numerical and structural aberrations. Moreover, we discovered in Thai chronic myelogenous leukaemia [CML] patients with complex translocations that a third and fourth chromosome were sometimes involved with the Philadelphia chromosome (9; 22) (q34; q11), creating three-way and four-way translocations.

Conclusion: The present study compiles the karyotypic analysis of 12,261 haematological cases which represents the largest dataset from Thailand. Chromosomal aberrations were found in one-third of
total cases. Our information should be of value to include in a national cancer registry.

Keywords: chromosome, haematological malignancy, karyotype, conventional cytogenetics, chromosomal aberrations