Genetics of lymphomas in Ecuador

Abstract

Abstract Lymphomas arise in any body region containing lymphatic tissue and are mainly classified into Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). This study summarizes genetic findings in Ecuadorian lymphoma patients from 1984 to the present, based on analyses from ten national centers. A total of 703 lymphomas were studied, with 12.4% HL and 87.6% NHL. Most cases occurred in males, and the most affected age group was over 60 years, consistent with global epidemiology. Genetic studies have evolved in Ecuador over the last four decades, incorporating conventional cytogenetics, fluorescence in situ hybridization (FISH), spectral karyotyping (SKY), PCR, Sanger sequencing, and Next-Generation Sequencing (NGS). Cytogenetic analysis revealed normal karyotypes in 70% of HL and 59.4% of NHL, with abnormal karyotypes in 17.6% of HL and 27.1% of NHL. FISH utilized probes for MYC, t(8;14), t(14;18), BCL2, BCL6, and TP53, supporting the identification of hallmark rearrangements. A key finding was the absence of the t(14;18) translocation in 65 NHL cases analyzed by PCR, suggesting it is rare in the Ecuadorian population, a result confirmed by FISH studies since 2012. Investigation of the hMSH2 gene variant rs2303428 in 22 NHL patients found a 22.73% frequency, suggesting an association with disease risk. A subsequent study on 87 NHL cases confirmed the finding, with a 0.09 allele frequency and significant differences from controls (p<0.01). NGS enabled the detection of rare and novel chromosomal alterations, such as the t(8;9)(q24;q33) MYC::FBXW2 fusion, not previously described in the literature. Within the Ibero-American Lymphoma Network, Ecuador reports a low incidence of follicular lymphoma, similar to other Andean countries but differing from Southern Cone nations, and clonality studies are not yet performed locally. These findings demonstrate the critical role of cytogenetic and molecular analysis in the accurate classification, treatment guidance, and follow-up of lymphoma patients. The rarity of certain rearrangements, the identification of unique genetic variants, and the growing use of advanced molecular tools highlight the importance of regional genomic studies to improve diagnosis and personalized medicine in Latin America.