Usefulness of long‐distance inverse polymerase chain reaction for molecular detection of 14q32 translocation in a clinical setting

Abstract

All mature B‐cell leukaemias and lymphomas have a clonal Ig gene recombination, and half of them have a reciprocal chromosomal translocation involving the 14q32 locus. The 14q32 translocation partners are variable, such as BCL‐2, BCL‐1 and BCL‐6, thus accounting for the difficulty in molecular detection by the current genomic polymerase chain reaction (PCR) method. To identify B‐cell clones efficiently with an Ig gene rearrangement and reciprocal inter‐chromosomal translocation, we verified the usefulness, in a practical laboratory setting, of our modified long‐distance inverse (LDI) PCR method for detecting IgH gene rearrangements involving inter‐ and intra‐chromosomal segments. The total run time of this LDI PCR method was 5.5 h. Using 24 samples of mature B‐cell leukaemias and lymphomas, the modified LDI PCR gave clonally rearranged amplicons in 83 % (20/24) of cases. Direct sequencing results of the amplicons revealed inter‐chromosomal translocations in 5 cases (25 %) and intra‐chromosomal rearrangements in the remaining 15 cases (75 %). The partners of the inter‐chromosomal translocation consisted of the 11q13.3 segment containing a partial BCL1 sequence in 3 cases; 18q21.3 segment containing a partial BCL2 sequence in one case; and a segment of 7q11.2 in one case. We present an LDI PCR‐based methodology for the efficient identification of 14q32 translocations, with modifications to reduce the total run time to within one day.

• B‐cell clonality
• IgH gene
• lymphoma
• PCR
• translocation
• 14q32

Acknowledgement

This work was supported in part by grants (no. 15659136) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.