The genetic information provided by FISH tests
can be critical for therapeutic decisions. Chemoimmunotherapy using fludarabine, cyclophosphamide and rituximab (FCR) receives a better treatment response from
patients with trisomy 12 or del(11q), whereas patients
with 17p deletions do not benefit from FCR treatment at
all [20,22]. In addition to the therapeutic significance,
FISH tests facilitate differential diagnosis between CLL
and other types of small B-cell lymphoma/leukemia. For
example, mantle cell lymphoma is morphologically similar
to CLL, but carries a characteristic genetic aberrancy, the
cyclin D1 translocation, and has a much worse prognosis.
The FISH test is the gold standard method of identifying