Diagnostic Use
This assay assesses immunoglobulin gene rearrangements to evaluate B-cell clonality and may aid in the detection of a clonal B-cell population in blood, bone marrow or tissue specimens.
Interpretation should be made in conjunction with clinical, morphological, immunophenotypic, and other laboratory findings. The primer sets used in this assay may not detect all immunoglobulin gene rearrangements; therefore, a clonal result does not alone establish a diagnosis of B-cell malignancy, and a negative result does not exclude the presence of a clonal B-cell disorder. The analytical sensitivity of clonality testing is estimated to be approximately 85-90% for B-cell lymphoproliferative neoplasms.
Interpretation
Information on Immunoglobin Gene Rearrangement analysis:
The Ig gene contains many different variable(V), diversity (D), and joining (J) gene segments which are rearranged during early lymphoid differentiation. Each committed B-cell precursor undergoes a unique rearrangement of their Ig heavy (IgH) and light chains during maturation, resulting in a specific Ig molecule. This rearrangement involves somatic DNA deletions, template-independent nucleotide additions and specific splicing involving the variable(V), diversity (D), and joining (J) regions of both the IgH and IgL genes. As each cell has a unique rearrangement of its Ig genes, these can act as a marker for monoclonal cellular expansion in cases of lymphoproliferative disease. PCR analysis using consensus primers within the variable region (FR2a or FR3a) are used with a downstream consensus primer within the joining region (LJH and VLJH). DNA from a normal polyclonal population of B cells will give multiple PCR bands which will look like a smear on an agarose gel and a monoclonal population will give a distinct band indicating just one rearrangement.
References:
Theriault C et al Modern Pathology 2000; 13(12): 1269-1279
Traunor KJ et al Blood 1991; 78(1):192-196
Test Method
PCR-based analysis of immunoglobulin heavy chain (IGH) gene rearrangements is performed using validated framework and joining region primers, based on previously published methods (Trainor et al. 1991; Thériault et al. 2000).