Telomere Length and Checkpoint Kinase Expression Patterns Across Cytogenetic Risk Groups in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) exhibits marked clinical heterogeneity that is closely associated with genomic instability. Although cytogenetic abnormalities are widely used for risk stratification, they do not fully capture the biological complexity of the disease. Telomere dysfunction and alterations in DNA damage response pathways have been implicated in disease progression, but their relationship with cytogenetic risk in CLL remains incompletely characterized. In this study, peripheral blood mononuclear cells (PBMCs) from 48 CLL patients were analyzed. The analyzed PBMC fractions were enriched in leukemic B cells, with an estimated median tumor content above 85–90%. Cytogenetic profiles were obtained by conventional karyotyping following in vitro immunostimulation with DSP30 and interleukin-2 and classified according to ERIC and Döhner criteria. Telomere length was assessed by quantitative PCR, and CHEK1 and CHEK2 expression levels were quantified by RT–qPCR. Molecular parameters were compared across cytogenetic risk groups. Distinct molecular profiles were observed across cytogenetic categories. Favorable-risk CLL cases showed preserved telomere length, low CHEK1 expression, and maintained CHEK2 levels. Intermediate-risk cases, predominantly characterized by trisomy 12, exhibited moderate telomere shortening accompanied by increased CHEK1 expression and partial reduction of CHEK2. High-risk CLL cases, defined by del(11q), del(17p), or complex karyotypes, displayed pronounced telomere shortening, marked CHEK1 upregulation, and strong suppression of CHEK2. Telomere length was inversely correlated with cytogenetic risk (Spearman’s ρ = −0.68, p < 0.0001), and the CHEK1/CHEK2 expression ratio increased progressively with genomic complexity. These findings indicate that telomere length and CHEK1/CHEK2 expression patterns are closely associated with cytogenetic risk in CLL and may provide complementary biological information for risk stratification.