Deletions of long arm of chromosome 14 rare (<5%) but recurrently observed in mature B-cell neoplasms, particularly in CLL.

Size of deletions variable, and molecular consequences unknown.

Data from 89 patients with CLL or Small Lymphocytic Lymphoma (SLL), harboring a del14q.

Compared with common CLL in literature, CLL with del14q dysplayed more tri12 (p<.03) and NOTCH1 mutations (p<.003), less del13q (p<.0006), more unmutated IGHV (p<.00001) and V1-69 repertoire (p<.00001).

Compared with common SLL in literature, SLL with del14q also exhibited more tri12, unmutated IGHV (p<.01) and V1-69 (p<.04).

14q deletions appeared distributed along chromosome 14 from bands q11 to q32.

Size of 14q deletion variable, with half of cases having recurrent interstitial deletion 14q24.1-14q32.3.

Both CLL and SLL with del14q, particularly with 14q24.1-14q32.3 deletion, associated with poor prognosis parameters (short time to treatment, trisomy 12, NOTCH1 mutated, and unmutated IGHV status), with overrepresentation of V1-69 gene.

Small sample -- needs to be further studied.

Associated with other poor prognosis parameters.

Unclear if can be considered independent marker for deciding therapy.