IgVH Mutation Analysis

This test determines the mutation status of IGHV gene in B lymphocytes, including those of CLL (chronic lymphocytic leukemia). The IGHV gene mutation status is one of the discriminators of clinical outcome in patients with CLL. The mutational status of the immunoglobulin genes expressed by CLL cells can be used to segregate patients into two subsets that have significantly different tendencies for disease progression. Patients with leukemic cells that express unmutated immunoglobulin heavy-chain variable region genes have a greater tendency for disease progression than those who have leukemic cells that express IGHV genes with less than 98% nucleic acid homology with their germ-line counterparts.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

The immunoglobulin heavy-chain gene variable region (IGHV) somatic hypermutation analysis is performed using extracted patient RNA as starting material. Subsequent amplification of the IgH gene is performed by polymerase chain reaction (PCR). The PCR products are isolated and sequenced. The nucleotide sequence is compared to a consensus germline sequence data base for that VH gene family. The results are reported as percentage of homology between the patient's VH sequence in comparison with the germline VH sequence using the Basic Local Alignment Search Tool (BLAST) for the Immunoglobulin data base at http://www.ncbi.nlm.nih.gov/igblast.