## Cytogenetics and Prognosis in CLL **Key Point:** Deletion 13q is the most common and most favorable cytogenetic abnormality in CLL, associated with longer overall survival and delayed need for treatment. ### CLL Cytogenetic Prognostic Hierarchy | Abnormality | Frequency | Median OS | Prognosis | |-------------|-----------|-----------|----------| | del 13q (sole) | 55% | >10 years | Favorable | | Trisomy 12 | 15% | 5–8 years | Intermediate | | Normal karyotype | 25% | 5–8 years | Intermediate | | del 11q | 10% | 5–7 years | Unfavorable | | del 17p | 5% | 2–3 years | Very unfavorable | ### Mechanism and Clinical Implications - **del 13q:** Involves loss of RB1 and other tumor suppressors; paradoxically associated with better outcomes - **del 17p:** Loss of TP53 (p53 tumor suppressor); highly aggressive, resistant to conventional therapy, requires novel agents (venetoclax, BTK inhibitors) - **del 11q:** ATM gene loss; intermediate-to-poor prognosis **High-Yield:** FISH panel for del 13q, del 11q, del 17p, and trisomy 12 is standard prognostic workup in newly diagnosed CLL and guides treatment decisions. **Clinical Pearl:** Patients with del 13q as sole abnormality may not require immediate treatment ("watch and wait"), whereas del 17p mandates early intervention with targeted agents. **Warning:** ~~Trisomy 12 is favorable~~ — it is actually intermediate prognosis. Do not confuse with del 13q.
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