Immunoglobulin heavy chain variable region (IgHv) refers to the variable region of the heavy chain of immunoglobulins, which are antibodies produced by B cells. In normal B cells, the IgHv region undergoes somatic hypermutation, a process in which the DNA sequence of the immunoglobulin genes is altered, leading to a diverse range of antibodies. IgHv mutation analysis is a laboratory technique used to determine the mutational status of IgHv  genes in B-cell malignancies, particularly chronic lymphocytic leukemia (CLL) and other lymphomas.

Based on the mutational status of the immunoglobulin heavy chain variable region genes, CLL patients can be divided into two groups: patients with somatic hypermutations and patients without somatic hypermutations. Patients with somatic hypermutations in the IgHv genes usually have longer survival and a better response to treatment than those without somatic hypermutations. IgHv mutation analysis, therefore, plays a crucial role in determining the course of treatment and predicting the progression of CLL. Understanding the mutation status helps oncologists tailor therapies to individual patients, providing a more personalized and effective approach to treatment.