Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma with Unmutated Immunoglobulin Heavy Chain Variable-Region Gene

**Semantic type:** Neoplastic Process

**Definition:** A recently recognized variant of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) that lacks somatic hypermutations of the Immunoglobulin heavy chain (IGH) genes, implying pregerminal center B-cell origin. Microarray gene expression profiling studies have demonstrated the expression of ZAP-70 gene (Syk family tyrosine kinase) in this subset of CLL/CLL. Patients with this variant of CLL/SLL have an unfavorable prognosis compared to those with somatic hypermutations of the IGH genes, with a median survival of approximately 6-8 years.

**Synonyms:** - CLL/SLL with Unmutated IGVH - Pregerminal Center Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma