Mu Heavy Chain Disease

**Semantic type:** Neoplastic Process

**Definition:** A clonal disorder characterized by the secretion of a mu heavy chain that lacks a variable region. Most patients present with slowly progressive chronic lymphocytic leukemia (CLL). In contrast to most cases of CLL, Mu heavy chain disease is associated with hepatosplenomegaly and absence of lymphadenopathy.

**Synonyms:** - Mu heavy chain disease